RESUMO
Diabetes (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. The combination of DM and HTN significantly accelerates development of renal injury; however, the underlying mechanisms of this synergy are still poorly understood. This study assessed whether mitochondria (MT) dysfunction is essential in developing renal injury in a rat model with combined DM and HTN. Type 1 DM was induced in Wistar rats by streptozotocin (STZ). HTN was induced six weeks later by inter-renal aorta constriction between the renal arteries, so that right kidneys were exposed to HTN while left kidneys were exposed to normotension. Kidneys exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion (UAE). In contrast, kidneys exposed to DM plus 8 weeks HTN had significantly increased UAE and glomerular structural damage with reduced glomerular filtration rate. Marked increases in MT-derived reactive oxygen species (ROS) were also observed in right kidneys exposed to HTN+DM. We further tested whether treatment with MT-targeted antioxidant (MitoTEMPO) after the onset of HTN attenuates renal injury in rats with DM+HTN. Results show that kidneys in DM+AC+MitoTEMPO rats had lower UAE, less glomerular damage, and preserved MT function compared to untreated DM+AC rats. Our studies indicate that MT-derived ROS play a major role in promoting kidney dysfunction when DM is combined with HTN. Preserving MT function might be a potential therapeutic approach to halt the development of renal injury when DM coexists with HTN.
RESUMO
Leptin regulates energy balance via leptin receptors expressed in central and peripheral tissues, but little is known about leptin-sensitive kidney genes and the role of the tubular leptin receptor (Lepr) in response to a high-fat diet (HFD). Quantitative RT-PCR analysis of Lepr splice variants A, B, and C revealed a ratio of â¼100:10:1 in the mouse kidney cortex and medulla, with medullary levels being â¼10 times higher. Leptin replacement in ob/ob mice for 6 days reduced hyperphagia, hyperglycemia, and albuminuria, associated with normalization of kidney mRNA expression of molecular markers of glycolysis, gluconeogenesis, amino acid synthesis, and megalin. Normalization of leptin for 7 h in ob/ob mice did not normalize hyperglycemia or albuminuria. Tubular knockdown of Lepr [Pax8-Lepr knockout (KO)] and in situ hybridization revealed a minor fraction of Lepr mRNA in tubular cells compared with endothelial cells. Nevertheless, Pax8-Lepr KO mice had lower kidney weight. Moreover, while HFD-induced hyperleptinemia, increases in kidney weight and glomerular filtration rate, and a modest blood pressure lowering effect were similar compared with controls, they showed a blunted rise in albuminuria. Use of Pax8-Lepr KO and leptin replacement in ob/ob mice identified acetoacetyl-CoA synthetase and gremlin 1 as tubular Lepr-sensitive genes that are increased and reduced by leptin, respectively. In conclusion, leptin deficiency may increase albuminuria via systemic metabolic effects that impinge on kidney megalin expression, whereas hyperleptinemia may induce albuminuria by direct tubular Lepr effects. Implications of Lepr variants and the novel tubular Lepr/acetoacetyl-CoA synthetase/gremlin 1 axis remain to be determined.NEW & NOTEWORTHY This study provides new insights into kidney gene expression of leptin receptor splice variants, leptin-sensitive kidney gene expression, and the role of the leptin receptor in renal tubular cells for the response to diet-induced hyperleptinemia and obesity including albuminuria.
Assuntos
Hiperglicemia , Leptina , Animais , Camundongos , Albuminúria/genética , Células Endoteliais/metabolismo , Expressão Gênica , Túbulos Renais/metabolismo , Leptina/genética , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Receptores para Leptina/genética , RNA MensageiroRESUMO
Diabetes mellitus (DM) and hypertension (HTN) are major risk factors for chronic kidney injury, together accounting for >70% of end-stage renal disease. In this study, we assessed whether DM and HTN interact synergistically to promote kidney dysfunction and whether transient receptor potential cation channel 6 (TRPC6) contributes to this synergism. In wild-type (WT; B6/129s background) and TRPC6 knockout (KO) mice, DM was induced by streptozotocin injection to increase fasting glucose levels to 250-350 mg/dL. HTN was induced by aorta constriction (AC) between the renal arteries. AC increased blood pressure (BP) by â¼25 mmHg in the right kidney (above AC), whereas BP in the left kidney (below AC) returned to near normal after 8 wk, with both kidneys exposed to the same levels of blood glucose, circulating hormones, and neural influences. Kidneys of WT mice exposed to DM or HTN alone had only mild glomerular injury and urinary albumin excretion. In contrast, WT kidneys exposed to DM plus HTN (WT-DM + AC mice) for 8 wk had much greater increases in albumin excretion and histological injury. Marked increased apoptosis was also observed in the right kidneys of WT-DM + AC mice. In contrast, in TRPC6 KO mice with DM + AC, right kidneys exposed to the same levels of high BP and high glucose had lower albumin excretion and less glomerular damage and apoptotic cell injury compared with right kidneys of WT-DM + AC mice. Our results suggest that TRPC6 may contribute to the interaction of DM and HTN to promote kidney dysfunction and apoptotic cell injury.NEW & NOTEWORTHY A major new finding of this study is that the combination of moderate diabetes and hypertension promoted marked renal dysfunction, albuminuria, and apoptotic cell injury, and that these effects were greatly ameliorated by transient receptor potential cation channel 6 deficiency. These results suggest that transient receptor potential cation channel 6 may play an important role in contributing to the interaction of diabetes and hypertension to promote kidney injury.
Assuntos
Apoptose , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Tipo 1/complicações , Taxa de Filtração Glomerular , Hipertensão/complicações , Rim/metabolismo , Insuficiência Renal Crônica/etiologia , Canal de Cátion TRPC6/metabolismo , Albuminúria/metabolismo , Albuminúria/patologia , Albuminúria/fisiopatologia , Animais , Glicemia/metabolismo , Pressão Sanguínea , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/fisiopatologia , Feminino , Hipertensão/metabolismo , Rim/patologia , Rim/fisiopatologia , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/patologia , Insuficiência Renal Crônica/fisiopatologia , Fatores de Risco , Canal de Cátion TRPC6/genéticaRESUMO
Transient receptor potential cation channel 6 (TRPC6), a member of the TRPC family, is expressed in the hypothalamus and modulates cell Ca2+ influx. However, the role of TRPC6 in controlling metabolic and cardiovascular functions under normal conditions has not been previously determined. Thus the impacts of TRPC6 deletion on energy balance, metabolic, and cardiovascular regulation as well as the anorexic responses to leptin and melanocortin 3/4 receptor (MC3/4R) activation were investigated in this study. Extensive cardiometabolic phenotyping was conducted in male and female TRPC6 knockout (KO) and control mice from 6 to 24 wk of age to assess mechanisms by which TRPC6 influences regulation of energy balance and blood pressure (BP). We found that TRPC6 KO mice are heavier with greater adiposity, are hyperphagic, and have reduced energy expenditure, impaired glucose tolerance, hyperinsulinemia, and increased liver fat compared with controls. TRPC6 KO mice also have smaller brains, reduced proopiomelanocortin mRNA levels in the hypothalamus, and impaired anorexic response to leptin but not to MC3/4R activation. BP and heart rate, assessed by telemetry, were similar in TRPC6 KO and control mice, and BP responses to air-jet stress were attenuated in TRPC6 KO mice despite increased body weight and metabolic disorders that normally raise BP and increase BP responses to stress. Our results provide evidence for a novel and important role of TRPC6 in controlling energy balance, adiposity, and glucose homeostasis, which suggests that normal TRPC6 function may be necessary to link weight gain and hyperleptinemia with BP responses to acute stress.
Assuntos
Canal de Cátion TRPC6 , Aumento de Peso , Animais , Anorexia , Pressão Sanguínea , Peso Corporal , Ingestão de Alimentos/fisiologia , Feminino , Leptina/metabolismo , Masculino , Camundongos , Camundongos Knockout , Obesidade/metabolismo , Canal de Cátion TRPC6/deficiência , Canal de Cátion TRPC6/metabolismo , Aumento de Peso/fisiologiaRESUMO
Inhibitors of proximal tubular Na+-glucose cotransporter 2 (SGLT2) are natriuretic, and they lower blood pressure. There are reports that the activities of SGLT2 and Na+-H+ exchanger 3 (NHE3) are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of an SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in nondiabetic mice with tubule-specific NHE3 knockdown (NHE3-ko) and wild-type (WT) littermates. A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate and raised urine pH in WT mice but not in NHE3-ko mice. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while cogenerated and excreted ammonium balances urine losses of this "potential bicarbonate." The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.
Assuntos
Compostos Benzidrílicos/farmacologia , Diabetes Mellitus/tratamento farmacológico , Glucosídeos/farmacologia , Túbulos Renais Proximais/efeitos dos fármacos , Natriurese/efeitos dos fármacos , Natriuréticos/farmacologia , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Transportador 2 de Glucose-Sódio/metabolismo , Trocador 3 de Sódio-Hidrogênio/metabolismo , Equilíbrio Ácido-Base/efeitos dos fármacos , Animais , Glicemia/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Diabetes Mellitus/metabolismo , Diabetes Mellitus/fisiopatologia , Modelos Animais de Doenças , Glicosúria/metabolismo , Glicosúria/fisiopatologia , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Trocador 3 de Sódio-Hidrogênio/deficiência , Trocador 3 de Sódio-Hidrogênio/genéticaRESUMO
PURPOSE OF REVIEW: To discuss the importance of synergistic interactions of diabetes mellitus (DM) and hypertension (HT) in causing chronic kidney disease and the potential molecular mechanisms involved. RECENT FINDINGS: DM and HT are the two most important risk factors for chronic kidney disease (CKD) and development of end-stage renal disease (ESRD). The combination of HT and DM may synergistically promote the progression of renal injury through mechanisms that have not been fully elucidated. Hyperglycemia and other metabolic changes in DM initiate endoplasmic reticulum (ER) stress and mitochondrial (MT) adaptation in different types of glomerular cells. These adaptations appear to make the cells more vulnerable to HT-induced mechanical stress. Excessive activation of mechanosensors, possibly via transient receptor potential cation channel subfamily C member 6 (TRPC6), may lead to impaired calcium (Ca2+) homeostasis and further exacerbate ER stress and MT dysfunction promoting cellular apoptosis and glomerular injury. The synergistic effects of HT and DM to promote kidney injury may be mediated by increased intraglomerular pressure. Chronic activation of mechanotransduction signaling may amplify metabolic effects of DM causing cellular injury through a vicious cycle of impaired Ca2+ homeostasis, mitochondrial dysfunction, and ER stress.
Assuntos
Diabetes Mellitus , Hipertensão , Mitocôndrias , Insuficiência Renal Crônica , Humanos , Mecanotransdução Celular , Mitocôndrias/fisiologiaRESUMO
Inhibitors of the Na+-glucose cotransporter SGLT2 enhance urinary glucose and urate excretion and lower plasma urate levels. The mechanisms remain unclear, but a role for enhanced glucose in the tubular fluid, which may interact with tubular urate transporters, such as the glucose transporter GLUT9 or the urate transporter URAT1, has been proposed. Studies were performed in nondiabetic mice treated with the SGLT2 inhibitor canagliflozin and in gene-targeted mice lacking the urate transporter Glut9 in the tubule or in mice with whole body knockout of Sglt2, Sglt1, or Urat1. Renal urate handling was assessed by analysis of urate in spontaneous plasma and urine samples and normalization to creatinine concentrations or by renal clearance studies with assessment of glomerular filtration rate by FITC-sinistrin. The experiments confirmed the contribution of URAT1 and GLUT9 to renal urate reabsorption, showing a greater contribution of the latter and additive effects. Genetic and pharmacological inhibition of SGLT2 enhanced fractional renal urate excretion (FE-urate), indicating that a direct effect of the SGLT2 inhibitor on urate transporters is not absolutely necessary. Consistent with a proposed role of increased luminal glucose delivery, the absence of Sglt1, which by itself had no effect on FE-urate, enhanced the glycosuric and uricosuric effects of the SGLT2 inhibitor. The SGLT2 inhibitor enhanced renal mRNA expression of Glut9 in wild-type mice, but tubular GLUT9 seemed dispensable for the increase in FE-urate in response to canagliflozin. First evidence is presented that URAT1 is required for the acute uricosuric effect of the SGLT2 inhibitor in mice.
Assuntos
Canagliflozina/farmacologia , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Túbulos Renais Proximais/efeitos dos fármacos , Transportadores de Ânions Orgânicos/metabolismo , Eliminação Renal/efeitos dos fármacos , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Transportador 2 de Glucose-Sódio/efeitos dos fármacos , Ácido Úrico/urina , Uricosúricos/farmacologia , Animais , Genótipo , Proteínas Facilitadoras de Transporte de Glucose/deficiência , Proteínas Facilitadoras de Transporte de Glucose/genética , Túbulos Renais Proximais/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transportadores de Ânions Orgânicos/deficiência , Transportadores de Ânions Orgânicos/genética , Fenótipo , Reabsorção Renal/efeitos dos fármacos , Transportador 2 de Glucose-Sódio/deficiência , Transportador 2 de Glucose-Sódio/genética , Transportador 2 de Glucose-Sódio/metabolismoRESUMO
Na+-glucose cotransporter (SGLT)1 mediates glucose reabsorption in late proximal tubules. SGLT1 also mediates macula densa (MD) sensing of an increase in luminal glucose, which increases nitric oxide (NO) synthase 1 (MD-NOS1)-mediated NO formation and potentially glomerular filtratrion rate (GFR). Here, the contribution of SGLT1 was tested by gene knockout (-/-) in type 1 diabetic Akita mice. A low-glucose diet was used to prevent intestinal malabsorption in Sglt1-/- mice and minimize the contribution of intestinal SGLT1. Hyperglycemia was modestly reduced in Sglt1-/- versus littermate wild-type Akita mice (480 vs. 550 mg/dl), associated with reduced diabetes-induced increases in GFR, kidney weight, glomerular size, and albuminuria. Blunted hyperfiltration was confirmed in streptozotocin-induced diabetic Sglt1-/- mice, associated with similar hyperglycemia versus wild-type mice (350 vs. 385 mg/dl). Absence of SGLT1 attenuated upregulation of MD-NOS1 protein expression in diabetic Akita mice and in response to SGLT2 inhibition in nondiabetic mice. During SGLT2 inhibition in Akita mice, Sglt1-/- mice had likewise reduced blood glucose (200 vs. 300 mg/dl), associated with lesser MD-NOS1 expression, GFR, kidney weight, glomerular size, and albuminuria. Absence of Sglt1 in Akita mice increased systolic blood pressure, associated with suppressed renal renin mRNA expression. This may reflect fluid retention due to blunted hyperfiltration. SGLT2 inhibition prevented the blood pressure increase in Sglt1-/- Akita mice, possibly due to additive glucosuric/diuretic effects. The data indicate that SGLT1 contributes to diabetic hyperfiltration and limits diabetic hypertension. Potential mechanisms include its role in glucose-driven upregulation of MD-NOS1 expression. This pathway may increase GFR to maintain volume balance when enhanced MD glucose delivery indicates upstream saturation of SGLTs and thus hyperreabsorption.
Assuntos
Glicemia/metabolismo , Diabetes Mellitus Experimental/enzimologia , Diabetes Mellitus Tipo 1/enzimologia , Nefropatias Diabéticas/enzimologia , Taxa de Filtração Glomerular , Rim/enzimologia , Óxido Nítrico Sintase Tipo I/metabolismo , Transportador 1 de Glucose-Sódio/deficiência , Albuminúria/enzimologia , Albuminúria/genética , Albuminúria/fisiopatologia , Animais , Biomarcadores/sangue , Glicemia/efeitos dos fármacos , Pressão Sanguínea , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/fisiopatologia , Nefropatias Diabéticas/sangue , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/fisiopatologia , Taxa de Filtração Glomerular/efeitos dos fármacos , Rim/efeitos dos fármacos , Rim/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Knockout , Óxido Nítrico Sintase Tipo I/genética , Reabsorção Renal , Renina/sangue , Renina/genética , Transdução de Sinais , Transportador 1 de Glucose-Sódio/genética , Transportador 2 de Glucose-Sódio , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Regulação para CimaRESUMO
Na+/H+ exchanger isoform 3 (NHE3) contributes to Na+/bicarbonate reabsorption and ammonium secretion in early proximal tubules. To determine its role in the diabetic kidney, type 1 diabetic Akita mice with tubular NHE3 knockdown [Pax8-Cre; NHE3-knockout (KO) mice] were generated. NHE3-KO mice had higher urine pH, more bicarbonaturia, and compensating increases in renal mRNA expression for genes associated with generation of ammonium, bicarbonate, and glucose (phosphoenolpyruvate carboxykinase) in proximal tubules and H+ and ammonia secretion and glycolysis in distal tubules. This left blood pH and bicarbonate unaffected in nondiabetic and diabetic NHE3-KO versus wild-type mice but was associated with renal upregulation of proinflammatory markers. Higher renal phosphoenolpyruvate carboxykinase expression in NHE3-KO mice was associated with lower Na+-glucose cotransporter (SGLT)2 and higher SGLT1 expression, indicating a downward tubular shift in Na+ and glucose reabsorption. NHE3-KO was associated with lesser kidney weight and glomerular filtration rate (GFR) independent of diabetes and prevented diabetes-associated albuminuria. NHE3-KO, however, did not attenuate hyperglycemia or prevent diabetes from increasing kidney weight and GFR. Higher renal gluconeogenesis may explain similar hyperglycemia despite lower SGLT2 expression and higher glucosuria in diabetic NHE3-KO versus wild-type mice; stronger SGLT1 engagement could have affected kidney weight and GFR responses. Chronic kidney disease in humans is associated with reduced urinary excretion of metabolites of branched-chain amino acids and the tricarboxylic acid cycle, a pattern mimicked in diabetic wild-type mice. This pattern was reversed in nondiabetic NHE3-KO mice, possibly reflecting branched-chain amino acids use for ammoniagenesis and tricarboxylic acid cycle upregulation to support formation of ammonia, bicarbonate, and glucose in proximal tubule. NHE3-KO, however, did not prevent the diabetes-induced urinary downregulation in these metabolites.
Assuntos
Equilíbrio Ácido-Base , Diabetes Mellitus Tipo 1/metabolismo , Nefropatias Diabéticas/metabolismo , Túbulos Renais/metabolismo , Reabsorção Renal , Trocador 3 de Sódio-Hidrogênio/deficiência , Sódio/urina , Equilíbrio Ácido-Base/genética , Aminoácidos de Cadeia Ramificada/urina , Amônia/urina , Animais , Bicarbonatos/urina , Biomarcadores/urina , Glicemia/metabolismo , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 1/urina , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/fisiopatologia , Nefropatias Diabéticas/urina , Modelos Animais de Doenças , Metabolismo Energético/genética , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Concentração de Íons de Hidrogênio , Túbulos Renais/fisiopatologia , Masculino , Metabolômica/métodos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transportador 1 de Glucose-Sódio/genética , Transportador 1 de Glucose-Sódio/metabolismo , Transportador 2 de Glucose-Sódio/genética , Transportador 2 de Glucose-Sódio/metabolismo , Trocador 3 de Sódio-Hidrogênio/genéticaRESUMO
The sodium-glucose cotransporter SGLT2 inhibitor empagliflozin (plasma protein binding ~88%) may reach its target in the brush border of the early proximal tubule by glomerular filtration and tubular secretion. Here we determined whether empagliflozin is secreted by renal tubules in mice and whether genetic knockout of the basolateral organic anion transporter 3 ( Oat3-/-) affects its tubular secretion or glucosuric effect. Renal clearance studies in wild-type (WT) mice showed that tubular secretion accounted for 50-70% of empagliflozin urinary excretion. Immunostaining indicated that SGLT2 and OAT3 localization partially overlapped in proximal tubule S1 and S2 segments. Glucosuria in metabolic cage studies was reduced in Oat3-/- vs. WT mice for acute empagliflozin doses of 1, 3, and 10 mg/kg, whereas 30 mg/kg induced similar maximal glucosuria in both genotypes. Chronic application of empagliflozin (~25 mg·kg-1 ·day-1) in Oat3-/- mice was associated with lower urinary glucose-to-creatinine ratios despite maintaining slightly higher blood glucose levels than WT. On a whole kidney level, renal secretion of empagliflozin was largely unchanged in Oat3-/- mice. However, the absence of OAT3 attenuated the influence of empagliflozin on fractional glucose excretion; higher levels of plasma or filtered empagliflozin were needed to induce similar increases in fractional renal glucose excretion. We conclude that empagliflozin is excreted into the urine to similar extent by glomerular filtration and tubular secretion. The latter can occur largely independent of OAT3. However, OAT3 increases the glucosuric effect of empagliflozin, which may relate to the partial overlap of its localization with SGLT2 and thus OAT3-mediated tubular secretion of empagliflozin in the early proximal tubule.
Assuntos
Compostos Benzidrílicos/farmacologia , Glicemia/efeitos dos fármacos , Glucosídeos/farmacologia , Glicosúria/metabolismo , Túbulos Renais Proximais/efeitos dos fármacos , Transportadores de Ânions Orgânicos Sódio-Independentes/metabolismo , Eliminação Renal , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Transportador 2 de Glucose-Sódio/efeitos dos fármacos , Animais , Compostos Benzidrílicos/farmacocinética , Compostos Benzidrílicos/urina , Glicemia/metabolismo , Taxa de Filtração Glomerular , Glucosídeos/farmacocinética , Glucosídeos/urina , Glicosúria/genética , Glicosúria/prevenção & controle , Túbulos Renais Proximais/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 1 Transportadora de Ânions Orgânicos/genética , Proteína 1 Transportadora de Ânions Orgânicos/metabolismo , Transportadores de Ânions Orgânicos Sódio-Independentes/deficiência , Transportadores de Ânions Orgânicos Sódio-Independentes/genética , Transportador 2 de Glucose-Sódio/metabolismo , Inibidores do Transportador 2 de Sódio-Glicose/farmacocinética , Inibidores do Transportador 2 de Sódio-Glicose/urinaRESUMO
Nitric oxide (NO) is an important negative modulator of tubuloglomerular feedback responsiveness. We recently found that macula densa expresses α-, ß-, and γ-splice variants of neuronal nitric oxide synthase 1 (NOS1), and NOS1ß expression in the macula densa increases on a high-salt diet. This study tested whether upregulation of NOS1ß expression in the macula densa affects sodium excretion and salt-sensitive hypertension by decreasing tubuloglomerular feedback responsiveness. Expression levels of NOS1ß mRNA and protein were 30- and five-fold higher, respectively, than those of NOS1α in the renal cortex of C57BL/6 mice. Furthermore, macula densa NO production was similar in the isolated perfused juxtaglomerular apparatus of wild-type (WT) and nitric oxide synthase 1α-knockout (NOS1αKO) mice. Compared with control mice, mice with macula densa-specific knockout of all nitric oxide synthase 1 isoforms (MD-NOS1KO) had a significantly enhanced tubuloglomerular feedback response and after acute volume expansion, significantly reduced GFR, urine flow, and sodium excretion. Mean arterial pressure increased significantly in MD-NOS1KO mice (P<0.01) but not NOS1flox/flox mice fed a high-salt diet. After infusion of angiotensin II, mean arterial pressure increased by 61.6 mmHg in MD-NOS1KO mice versus 32.0 mmHg in WT mice (P<0.01) fed a high-salt diet. These results indicate that NOS1ß is a primary NOS1 isoform expressed in the macula densa and regulates the tubuloglomerular feedback response, the natriuretic response to acute volume expansion, and the development of salt-sensitive hypertension. These findings show a novel mechanism for salt sensitivity of BP and the significance of tubuloglomerular feedback response in long-term control of sodium excretion and BP.
Assuntos
Hipertensão/enzimologia , Hipertensão/etiologia , Sistema Justaglomerular/enzimologia , Óxido Nítrico Sintase Tipo I/fisiologia , Cloreto de Sódio na Dieta/efeitos adversos , Animais , Hipertensão/prevenção & controle , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico Sintase Tipo I/uso terapêuticoRESUMO
Adenosine plays an important role in regulation of renal microcirculation. All receptors of adenosine, A1, A2A, A2B, and A3, have been found in the kidney. However, little is known about the location and function of the A3 receptor in the kidney. The present study determined the expression and role of A3 receptors in mediating the afferent arteriole (Af-Art) response and studied the interaction of A3 receptors with angiotensin II (ANG II), A1 and A2 receptors on the Af-Art. We found that the A3 receptor expressed in microdissected isolated Af-Art and the mRNA levels of A3 receptor were 59% of A1. In the isolated microperfused Af-Art, A3 receptor agonist IB-MECA did not have a constrictive effect. Activation of A3 receptor dilated the preconstricted Af-Art by norepinephrine and blunted the vasoconstrictive effect of both adenosine A1 receptor activation and ANG II on the Af-Art, respectively. Selective A2 receptor antagonist (both A2A and A2B) had no effect on A3 receptor agonist-induced vasodilation, indicating that the dilatory effect of A3 receptor activation is not mediated by activation of A2 receptor. We conclude that the A3 receptor is expressed in the Af-Art, and activation of the A3 receptor dilates the Af-Art.
Assuntos
Rim/irrigação sanguínea , Receptor A3 de Adenosina/metabolismo , Circulação Renal , Vasodilatação , Agonistas do Receptor A3 de Adenosina/farmacologia , Angiotensina II/metabolismo , Animais , Arteríolas/metabolismo , Relação Dose-Resposta a Droga , Masculino , Camundongos Endogâmicos C57BL , RNA Mensageiro/metabolismo , Receptor Cross-Talk , Receptor A1 de Adenosina/metabolismo , Receptor A3 de Adenosina/efeitos dos fármacos , Receptor A3 de Adenosina/genética , Receptores A2 de Adenosina/metabolismo , Circulação Renal/efeitos dos fármacos , Transdução de Sinais , Vasodilatação/efeitos dos fármacosRESUMO
Peroxisome proliferator-activated receptor-γ (PPARγ) agonists like pioglitazone (PGZ) are effective antidiabetic drugs, but they induce fluid retention and body weight (BW) gain. Dipeptidyl peptidase IV (DPP IV) inhibitors are antidiabetic drugs that enhance renal Na(+) and fluid excretion. Therefore, we examined whether the DPP IV inhibitor alogliptin (ALG) ameliorates PGZ-induced BW gain. Male Sv129 mice were treated with vehicle (repelleted diet), PGZ (220 mg/kg diet), ALG (300 mg/kg diet), or a combination of PGZ and ALG (PGZ + ALG) for 14 days. PGZ + ALG prevented the increase in BW observed with PGZ but did not attenuate the increase in body fluid content determined by bioimpedance spectroscopy (BIS). BIS revealed that ALG alone had no effect on fat mass (FM) but enhanced the FM-lowering effect of PGZ; MRI analysis confirmed the latter and showed reductions in visceral and inguinal subcutaneous (sc) white adipose tissue (WAT). ALG but not PGZ decreased food intake and plasma free fatty acid concentrations. Conversely, PGZ but not ALG increased mRNA expression of thermogenesis mediator uncoupling protein 1 in epididymal WAT. Adding ALG to PGZ treatment increased the abundance of multilocular cell islets in sc WAT, and PGZ + ALG increased the expression of brown-fat-like "beige" cell marker TMEM26 in sc WAT and interscapular brown adipose tissue and increased rectal temperature vs. vehicle. In summary, DPP IV inhibition did not attenuate PPARγ agonist-induced fluid retention but prevented BW gain by reducing FM. This involved ALG inhibition of food intake and was associated with food intake-independent synergistic effects of PPARγ agonism and DPP-IV inhibition on beige/brown fat cells and thermogenesis.
Assuntos
Tecido Adiposo Marrom/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Inibidores da Dipeptidil Peptidase IV/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , PPAR gama/agonistas , Piperidinas/farmacologia , Uracila/análogos & derivados , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Adipócitos Marrons/efeitos dos fármacos , Animais , Masculino , Camundongos , Pioglitazona , Tiazolidinedionas/farmacologia , Uracila/farmacologiaRESUMO
An increase in renal sodium chloride (salt) retention and an increase in sodium appetite are the body's responses to salt restriction or depletion in order to restore salt balance. Renal salt retention and increased sodium appetite can also be maladaptive and sustain the pathophysiology in conditions like salt-sensitive hypertension and chronic heart failure. Here we review the central role of the mineralocorticoid aldosterone in both the increase in renal salt reabsorption and sodium appetite. We discuss the working hypothesis that aldosterone activates similar signaling and effector mechanisms in the kidney and brain, including the mineralocorticoid receptor, the serum- and glucocorticoid-induced kinase SGK1, the ubiquitin ligase NEDD4-2, and the epithelial sodium channel ENaC. The latter also mediates the gustatory salt sensing in the tongue, which is required for the manifestation of increased salt intake. Effects of aldosterone on both the brain and kidney synergize with the effects of angiotensin II. Thus, mineralocorticoids appear to induce similar molecular pathways in the kidney, brain, and possibly tongue, which could provide opportunities for more effective therapeutic interventions. Inhibition of renal salt reabsorption is compensated by stimulation of salt appetite and vice versa; targeting both mechanisms should be more effective. Inhibiting the arousal to consume salty food may improve a patient's compliance to reducing salt intake. While a better understanding of the molecular mechanisms is needed and will provide new therapeutic options, current pharmacological interventions that target both salt retention and sodium appetite include mineralocorticoid receptor antagonists and potentially inhibitors of angiotensin II and ENaC.
Assuntos
Aldosterona/metabolismo , Mineralocorticoides/metabolismo , Cloreto de Sódio/metabolismo , Angiotensina II/metabolismo , Animais , Apetite/fisiologia , Pressão Sanguínea/fisiologia , Canais Epiteliais de Sódio , Humanos , Hipertensão/etiologia , Hipertensão/metabolismo , Rim/fisiologia , Antagonistas de Receptores de Mineralocorticoides/uso terapêutico , Receptores de Mineralocorticoides/metabolismo , Transdução de Sinais , Equilíbrio HidroeletrolíticoRESUMO
BACKGROUND: This study aimed to compare the efficacy of intra-articular prolotherapy (IG) combined with peri-articular perineural injection (PG) in the management of knee osteoarthritis (KOA). METHODS: A total of 60 patients with the diagnosis of KOA were included in this double-blinded randomized controlled clinical trials. The inclusion criteria were as follow: (1) 48-80 years old; (2) the diagnose of KOA; (3) the grade 2 and 3 of the Kellgern-Lawrence grading scale; (4) the pain, crepitation, and knee joint stiffness continuing for 3 months at least. The main exclusion criteria were as follow: (1) any infection involving the knee skin; (2) history of any Influencing factors of disease. All patients were divided into three groups and received either IG, PG and I + PG under the ultrasound guidance and the 2, 4 and 8 weeks follow-up data of patients were available. (IG n = 20 or PG n = 20, I + PG n = 20). Visual Analogue Scale (VAS), The Western Ontario McMaster University Osteoarthritis Index (WOMAC) and the pressure pain threshold (PPT) were used as outcome measures at baseline, 2, 4 and 8 weeks. RESULTS: There were no statistically significant differences in terms of age, sex, BMI, duration of current condition and baseline assessments of pain intensity, WOMAC scores and PPT. After treatment, the improvement of VAS activity, WOMAC and PPT values was showed compared with pre-treatment in all groups (p < 0.05). At 4 and 8 weeks after treatment, the VAS and WOMAC scores of the I + PG were significantly lower than those of the PG or IG, and the difference was statistically significant (p < 0.05). The PPT values of PG and I + PG were significantly improved compared to IG at 2, 4, and 8 weeks after treatment. CONCLUSION: The ultrasound guided I + PG of 5% glucose seem to be more effective to alleviate pain and improve knee joint function than single therapy in short term. Clinical rehabilitators could clinically try this combination of I + PG to improve clinical symptoms in patients with KOA.
Assuntos
Osteoartrite do Joelho , Proloterapia , Humanos , Osteoartrite do Joelho/tratamento farmacológico , Feminino , Masculino , Pessoa de Meia-Idade , Injeções Intra-Articulares , Proloterapia/métodos , Idoso , Método Duplo-Cego , Resultado do Tratamento , Idoso de 80 Anos ou mais , Medição da Dor , Ultrassonografia de Intervenção/métodos , Terapia CombinadaRESUMO
Males have higher prevalence of hypertension and renal injury than females, which may be attributed in part to androgen-mediated effects on renal hemodynamics. Tubuloglomerular feedback (TGF) is an important mechanism in control of renal microcirculation. The present study examines the role of testosterone in the regulation of TGF responses. TGF was measured by micropuncture (change of stop-flow pressure, ΔPsf) in castrated Sprague-Dawley rats. The addition of testosterone (10(-7) mol/l) into the lumen increased the ΔPsf from 10.1 ± 1.2 to 12.2 ± 1.2 mmHg. To determine whether androgen receptors (AR) are involved, mRNA of AR was measured in the macula dense cells isolated by laser capture microdissection from kidneys, and a macula densa-like cell line (MMDD1). AR mRNA was expressed in the macula densa of rats and in MMDD1 cells. We next examined the effects of the AR blocker, flutamide (10(-5) mol/l) on the TGF response. The addition of flutamide blocked the effects of testosterone on TGF. The addition of Tempol (10(-4) mol/l) or polyethylene glycol-superoxide dismutase (100 U/ml) to scavenge superoxide blocked the effect of testosterone to augment TGF. We then applied apocynin to inhibit NAD(P)H oxidase and oxypurinol to inhibit xanthine oxidase and found the testosterone-induced augmentation of TGF was blocked. In additional experiments in MMDD1 cells, we found that testosterone increased O2(-) generation. Apocynin or oxypurinol blocked the testosterone-induced increases of O2(-), while blockade of COX-2 with NS-398 had no effect. These findings suggest that testosterone enhances TGF response by stimulating O2(-) production in macula densa via an AR-dependent pathway.
Assuntos
Retroalimentação Fisiológica/efeitos dos fármacos , Glomérulos Renais/efeitos dos fármacos , Túbulos Renais/efeitos dos fármacos , Superóxidos/metabolismo , Testosterona/farmacologia , Antagonistas de Androgênios/farmacologia , Animais , Linhagem Celular , Óxidos N-Cíclicos/farmacologia , Inibidores de Ciclo-Oxigenase 2/farmacologia , Flutamida/farmacologia , Sequestradores de Radicais Livres/farmacologia , Masculino , NADPH Oxidases/metabolismo , Nitrobenzenos/farmacologia , RNA/biossíntese , RNA/genética , Ratos , Ratos Sprague-Dawley , Receptores Androgênicos/efeitos dos fármacos , Marcadores de Spin , Sulfonamidas/farmacologia , Superóxido Dismutase/farmacologia , Xantina Oxidase/metabolismoRESUMO
OBJECTIVE: To investigate potential pathogens in waters of Xiamen from Jiulong River, and to provide useful information for the prevention and control of potential pathogen infections. METHODS: All samples were spread on Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar plates, and then incubated at 26 +/- 1 degrees C for 24 +/- 2 h. In total 158 TCBS strains were isolated from TCBS agar plates and pure-cultivated on 2216E agar plates. All strains were identified using the 16S rRNA gene- Restriction fragment length polymorphism (RFLP), 16S rRNA sequence analysis, GenBank database Basic Local Alignment Search Tool (BLAST) and phylogenetic analysis. RESULTS: The results show that 158 TCBS strains from the sediments of Jiulong River estuary were classfied as 7 genus, which were Pseudomonas (28%), Aeromonas (24%), Pseudoalteromonas (19%), Shewanella (13%), Bacillus (11%), Vibrio (4%) and Psychrobacter (1%). The composition and distribution of TCBS bacteria groups varied with stations. Non-halophilic or haloduric bacteria groups were dominant in the upper area of Jiulong River estuary, and halophilic and haloduric bacteria were dominant in the lower area, which characterized a typical estuary feature. The salinity played a key role in the distribution of TCBS groups. Vibrios did not constitute a significant proportion (6% - 19%) of the total TCBS strains at different stations, and most of the them distributed at the lower region. CONCLUSION: There were a lot of potential pathogens in Jiulong River estuary. Aeromonas, a typical genus of halotolerant bacteria, was the potentially terrigenous bacteria contamination to the waters of Xiamen. Most Vibrio specieses were marine aborigines, which was not directly contaminated from the runoff of Jiulong River.
Assuntos
Bactérias/isolamento & purificação , Sedimentos Geológicos/microbiologia , Rios/microbiologia , Água do Mar/microbiologia , Bactérias/classificação , Bactérias/genética , Técnicas Bacteriológicas/métodos , Ácidos e Sais Biliares , Citratos , Meios de Cultura , Filogenia , Sacarose , TiossulfatosRESUMO
Background and Aims: The prognosis of liver cancer is strongly influenced by microvascular infiltration (MVI). Accurate preoperative MVI prediction can aid clinicians in the selection of suitable treatment options. In this study, we constructed a novel, reliable, and adaptable nomogram for predicting MVI. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, we extracted the clinical data of 1,063 patients diagnosed with hepatocellular carcinoma (HCC) and divided it into either a training (n = 739) or an internal validation cohort (n = 326). Based on multivariate analysis, the training cohort data were analyzed and a nomogram was generated for MVI prediction. This was further verified using an internal validation cohort and an external validation cohort involving 293 Chinese patients. Furthermore, to evaluate the efficacy, accuracy, and clinical use of the nomogram, we used concordance index (C-index), calibration curve, and decision curve analysis (DCA) techniques. Results: In accordance with the multivariate analysis, tumor size, tumor number, alpha-fetoprotein (AFP), and histological grade were independently associated with MVI. The established model exhibited satisfactory performance in predicting MVI. The C-indices were 0.719, 0.704, and 0.718 in the training, internal validation, and external validation cohorts, respectively. The calibration curves showed an excellent consistency between the predictions and actual observations. Finally, DCA demonstrated that the newly developed nomogram had favorable clinical utility. Conclusions: We established and verified a novel preoperative MVI prediction model in HCC patients. This model can be a beneficial tool for clinicians in selecting an optimal treatment plan for HCC patients.
RESUMO
Two major factors which regulate tubuloglomerular feedback (TGF)-mediated constriction of the afferent arteriole are release of superoxide (O(2)(-)) and nitric oxide (NO) by macula densa (MD) cells. MD O(2)(-) inactivates NO; however, among the factors that increase MD O(2)(-) release, the role of aldosterone is unclear. We hypothesize that aldosterone activates the mineralocorticoid receptor (MR) on MD cells, resulting in increased O(2)(-) production due to upregulation of cyclooxygenase-1 (COX-2) and NOX-2, and NOX-4, isoforms of NAD(P)H oxidase. Studies were performed on MMDD1 cells, a renal epithelial cell line with properties of MD cells. RT-PCR and Western blotting confirmed the expression of MR. Aldosterone (10(-8) mol/l for 30 min) doubled MMDD1 cell O(2)(-) production, and this was completely blocked by MR inhibition with 10(-5) mol/l eplerenone. RT-PCR, real-time PCR, and Western blotting demonstrated aldosterone-induced increases in COX-2, NOX-2, and NOX-4 expression. Inhibition of COX-2 (NS398), NADPH oxidase (apocynin), or a combination blocked aldosterone-induced O(2)(-) production to the same degree. These data suggest that aldosterone-stimulated MD O(2)(-) production is mediated by COX-2 and NADPH oxidase. Next, COX-2 small-interfering RNA (siRNA) specifically decreased COX-2 mRNA without affecting NOX-2 or NOX-4 mRNAs. In the presence of the COX-2 siRNA, the aldosterone-induced increases in COX-2, NOX-2, and NOX-4 mRNAs and O(2)(-) production were completely blocked, suggesting that COX-2 causes increased expression of NOX-2 and NOX-4. In conclusion 1) MD cells express MR; 2) aldosterone increases O(2)(-) production by activating MR; and 3) aldosterone stimulates COX-2, which further activates NOX-2 and NOX-4 and generates O(2)(-). The resulting balance between O(2)(-) and NO in the MD is important in modulating TGF.
Assuntos
Aldosterona/farmacologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Rim/efeitos dos fármacos , Rim/metabolismo , Superóxidos/metabolismo , Acetofenonas/farmacologia , Animais , Linhagem Celular , Ciclo-Oxigenase 2/efeitos dos fármacos , Ciclo-Oxigenase 2/metabolismo , Inibidores de Ciclo-Oxigenase 2/farmacologia , Inibidores Enzimáticos/farmacologia , Células Epiteliais/citologia , Rim/citologia , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Transgênicos , Modelos Animais , NADPH Oxidase 2 , NADPH Oxidase 4 , NADPH Oxidases/antagonistas & inibidores , NADPH Oxidases/metabolismo , Nitrobenzenos/farmacologia , RNA Interferente Pequeno/farmacologia , Receptores de Mineralocorticoides/metabolismo , Sulfonamidas/farmacologiaRESUMO
Neuronal nitric oxide synthase (nNOS), which is abundantly expressed in the macula densa cells, attenuates tubuloglomerular feedback (TGF). We hypothesize that splice variants of nNOS are expressed in the macula densa, and nNOS-beta is a salt-sensitive isoform that modulates TGF. Sprague-Dawley rats received a low-, normal-, or high-salt diet for 10 days and levels of the nNOS-alpha, nNOS-beta, and nNOS-gamma were measured in the macula densa cells isolated with laser capture microdissection. Three splice variants of nNOS, alpha-, beta-, and gamma-mRNAs, were detected in the macula densa cells. After 10 days of high-salt intake, nNOS-alpha decreased markedly, whereas nNOS-beta increased two- to threefold in the macula densa measured with real-time PCR and in the renal cortex measured with Western blot. NO production in the macula densa was measured in the perfused thick ascending limb with an intact macula densa plaque with a fluorescent dye DAF-FM. When the tubular perfusate was switched from 10 to 80 mM NaCl, a maneuver to induce TGF, NO production by the macula densa was increased by 38 +/- 3% in normal-salt rats and 52 +/- 6% (P < 0.05) in the high-salt group. We found 1) macula densa cells express nNOS-alpha, nNOS-beta, and nNOS-gamma, 2) a high-salt diet enhances nNOS-beta, and 3) TGF-induced NO generation from macula densa is enhanced in high-salt diet possibly from nNOS-beta. In conclusion, we found that the splice variants of nNOS expressed in macula densa cells were alpha-, beta-, and gamma-isoforms and propose that enhanced level of nNOS-beta during high-salt intake may contribute to macula densa NO production and help attenuate TGF.