RESUMO
Sodium-glucose cotransporter-2 inhibitors (SGLT2i) reduce blood pressure (BP) in patients with hypertension, yet the precise molecular mechanisms remain elusive. SGLT2i inhibits proximal tubule (PT) NHE3-mediated sodium reabsorption in normotensive rodents, yet no hypotensive effect is observed under this scenario. This study examined the effect of empagliflozin (EMPA) on renal tubular sodium transport in normotensive and spontaneously hypertensive rats (SHRs). It also tested the hypothesis that EMPA-mediated PT NHE3 inhibition in normotensive rats is associated with upregulation of distal nephron apical sodium transporters. EMPA administration for 14 days reduced BP in 12-wk-old SHRs but not in age-matched Wistar rats. PT NHE3 activity was inhibited by EMPA treatment in both Wistar and SHRs. In Wistar rats, EMPA increased NCC activity, mRNA expression, protein abundance, and phosphorylation levels, but not in SHRs. SHRs showed higher NKCC2 activity and an abundance of cleaved ENaC α and γ subunits compared with Wistar rats, none of which were affected by EMPA. Another set of male Wistar rats was treated with EMPA, the NCC inhibitor hydrochlorothiazide (HCTZ), and EMPA combined with HCTZ or vehicle for 14 days. In these rats, BP reduction was observed only with combined EMPA and HCTZ treatment, not with either drug alone. These findings suggest that NCC upregulation counteracts EMPA-mediated inhibition of PT NHE3 in male normotensive rats, maintaining their baseline BP. Moreover, the reduction of NHE3 activity without further upregulation of major apical sodium transporters beyond the PT may contribute to the BP-lowering effect of SGLT2i in experimental models and patients with hypertension.NEW & NOTEWORTHY This study suggests that reduced NHE3-mediated sodium reabsorption in the renal proximal tubule may account, at least in part, for the BP-lowering effect of SGLT2 inhibitors in the setting of hypertension. It also demonstrates that chronic treatment with SGLT2 inhibitors upregulates NCC activity, phosphorylation, and expression in the distal tubule of normotensive but not hypertensive rats. SGLT2 inhibitor-mediated upregulation of NCC seems crucial to counteract proximal tubule natriuresis in subjects with normal BP.
Assuntos
Compostos Benzidrílicos , Glucosídeos , Hipertensão , Ratos Endogâmicos SHR , Ratos Wistar , Inibidores do Transportador 2 de Sódio-Glicose , Trocador 3 de Sódio-Hidrogênio , Regulação para Cima , Animais , Masculino , Trocador 3 de Sódio-Hidrogênio/metabolismo , Trocador 3 de Sódio-Hidrogênio/genética , Trocador 3 de Sódio-Hidrogênio/antagonistas & inibidores , Hipertensão/tratamento farmacológico , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Glucosídeos/farmacologia , Compostos Benzidrílicos/farmacologia , Regulação para Cima/efeitos dos fármacos , Ratos , Inibidores do Transportador 2 de Sódio-Glicose/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Membro 3 da Família 12 de Carreador de Soluto/genética , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/metabolismo , Rim/metabolismo , Rim/efeitos dos fármacosRESUMO
Aldosterone is responsible for maintaining volume and potassium homeostasis. Although high salt consumption should suppress aldosterone production, individuals with hyperaldosteronism lose this regulation, leading to a state of high aldosterone despite dietary sodium consumption. The present study examines the effects of elevated aldosterone, with or without high salt consumption, on the expression of key Na+ transporters and remodelling in the distal nephron. Epithelial sodium channel (ENaC) α-subunit expression was increased with aldosterone regardless of Na+ intake. However, ENaC ß- and γ-subunits unexpectedly increased at both a transcript and protein level with aldosterone when high salt was present. Expression of total and phosphorylated Na+ Cl- cotransporter (NCC) significantly increased with aldosterone, in association with decreased blood [K+ ], but the addition of high salt markedly attenuated the aldosterone-dependent NCC increase, despite equally severe hypokalaemia. We hypothesized this was a result of differences in distal convoluted tubule length when salt was given with aldosterone. Imaging and measurement of the entire pNCC-positive tubule revealed that aldosterone alone caused a shortening of this segment, although the tubule had a larger cross-sectional diameter. This was not true when salt was given with aldosterone because the combination was associated with a lengthening of the tubule in addition to increased diameter, suggesting that differences in the pNCC-positive area are not responsible for differences in NCC expression. Together, our results suggest the actions of aldosterone, and the subsequent changes related to hypokalaemia, are altered in the presence of high dietary Na+ . KEY POINTS: Aldosterone regulates volume and potassium homeostasis through effects on transporters in the kidney; its production can be dysregulated, preventing its suppression by high dietary sodium intake. Here, we examined how chronic high sodium consumption affects aldosterone's regulation of sodium transporters in the distal nephron. Our results suggest that high sodium consumption with aldosterone is associated with increased expression of all three epithelial sodium channel subunits, rather than just the alpha subunit. Aldosterone and its associated decrease in blood [K+ ] lead to an increased expression of Na-Cl cotransporter (NCC); the addition of high sodium consumption with aldosterone partially attenuates this NCC expression, despite similarly low blood [K+ ]. Upstream kinase regulators and tubule remodelling do not explain these results.
Assuntos
Hipopotassemia , Sódio na Dieta , Humanos , Sódio na Dieta/farmacologia , Sódio na Dieta/metabolismo , Sódio/metabolismo , Aldosterona/farmacologia , Aldosterona/metabolismo , Canais Epiteliais de Sódio/metabolismo , Hipopotassemia/metabolismo , Túbulos Renais Distais/metabolismo , Cloreto de Sódio na Dieta , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Potássio/metabolismoRESUMO
After more than 30 years of extensive investigation, impressive progress has been made in identifying the neural correlates of consciousness (NCC). However, the functional role of spatiotemporally distinct consciousness-related neural activity in conscious perception is debated. An influential framework proposed that consciousness-related neural activities could be dissociated into two distinct processes: phenomenal and access consciousness. However, though hotly debated, its authenticity has not been examined in a single paradigm with more informative intracranial recordings. In the present study, we employed a visual awareness task and recorded the local field potential (LFP) of patients with electrodes implanted in cortical and subcortical regions. Overall, we found that the latency of visual awareness-related activity exhibited a bimodal distribution, and the recording sites with short and long latencies were largely separated in location, except in the lateral prefrontal cortex (lPFC). The mixture of short and long latencies in the lPFC indicates that it plays a critical role in linking phenomenal and access consciousness. However, the division between the two is not as simple as the central sulcus, as proposed previously. Moreover, in 4 patients with electrodes implanted in the bilateral prefrontal cortex, early awareness-related activity was confined to the contralateral side, while late awareness-related activity appeared on both sides. Finally, Granger causality analysis showed that awareness-related information flowed from the early sites to the late sites. These results provide the first LFP evidence of neural correlates of phenomenal and access consciousness, which sheds light on the spatiotemporal dynamics of NCC in the human brain.
Assuntos
Conscientização , Estado de Consciência , Humanos , Estado de Consciência/fisiologia , Masculino , Feminino , Adulto , Conscientização/fisiologia , Percepção Visual/fisiologia , Eletrocorticografia , Encéfalo/fisiologia , Adulto Jovem , Eletrodos Implantados , Córtex Pré-Frontal/fisiologiaRESUMO
We have previously observed that prolonged administration of rapamycin, an inhibitor targeting the mammalian target of rapamycin complex (mTORC)1, partially reduced hypertension and alleviated kidney inflammation in Dahl salt-sensitive (SS) rats. In contrast, treatment with PP242, an inhibitor affecting both mTORC1/mTORC2, not only completely prevented hypertension but also provided substantial protection against kidney injury. Notably, PP242 exhibited potent natriuretic effects that were not evident with rapamycin. The primary objective of this study was to pinpoint the specific tubular sites responsible for the natriuretic effect of PP242 in SS rats subjected to either 0.4% NaCl (normal salt) or 4.0% NaCl (high salt) diet. Acute effects of PP242 on natriuretic, diuretic, and kaliuretic responses were determined in unanesthetized SS rats utilizing benzamil, furosemide, or hydrochlorothiazide [inhibitors of epithelial Na+ channel (ENaC), Na-K-2Cl cotransporter (NKCC2), or Na-Cl cotransporter (NCC), respectively] either administered alone or in combination. The findings indicate that the natriuretic effects of PP242 in SS rats stem predominantly from the inhibition of NCC and a reduction of ENaC open probability. Molecular analysis revealed that mTORC2 regulates NCC activity through protein phosphorylation and ENaC activity through proteolytic cleavage in vivo. Evidence also indicated that PP242 also prevents the loss of K+ associated with the inhibition of NCC. These findings suggest that PP242 may represent an improved therapeutic approach for antihypertensive intervention, potentially controlling blood pressure and mitigating kidney injury in salt-sensitive human subjects.NEW & NOTEWORTHY This study explored mechanisms underlying the natriuretic effects of mammalian target of rapamycin protein complex 2 inhibition using PP242 and revealed both epithelial Na+ channel and Na-Cl cotransporter in the distal tubular segments were potentially inhibited. These observations, with prior lab evidence, indicate that PP242 prevents hypertension via its potent inhibitory effects on these specific sodium transporters and by reducing renal immune responses. This dual action, coupled with potassium sparing effects, suggests an improved approach for managing hypertension and associated kidney damage.
Assuntos
Canais Epiteliais de Sódio , Alvo Mecanístico do Complexo 2 de Rapamicina , Natriurese , Ratos Endogâmicos Dahl , Cloreto de Sódio na Dieta , Membro 3 da Família 12 de Carreador de Soluto , Animais , Canais Epiteliais de Sódio/metabolismo , Natriurese/efeitos dos fármacos , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Masculino , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Hipertensão/metabolismo , Hipertensão/tratamento farmacológico , Hipertensão/fisiopatologia , Rim/efeitos dos fármacos , Rim/metabolismo , Modelos Animais de Doenças , Ratos , Amilorida/farmacologia , Amilorida/análogos & derivados , Pressão Sanguínea/efeitos dos fármacos , Fosforilação , Transdução de Sinais/efeitos dos fármacos , Indóis , PurinasRESUMO
This review highlights the molecular basis of salt sensitivity in hypertension, with a focus on the regulation of sodium transport in the distal nephron. Sodium reabsorption in this region is often linked to the actions of aldosterone, although in recent years numerous findings have been reported on the aldosterone-independent pathway of acquiring salt sensitivity by potassium deficiency or potassium loading. The key to this discussion is the interplay, through extracellular potassium concentration, between the first part of the tubules expressing the Na+-Cl- cotransporter (NCC) and the second part expressing the epithelial Na+ channel (ENaC). The molecular pathways such as with-no-lysine 1 (WNK)-STE20/SPS1-related proline-alanine-rich kinase (SPAK)/oxidative stress-responsive kinase 1 (OSR1) signaling, Kelch-like family member 3 (KLHL3)-cullin 3 (CUL3) complex, protein phosphatases, and mechanistic target of rapamycin complex 2 (mTORC2)-Nedd4L pathway are described as the mechanism by which salt sensitivity on blood pressure is acquired in response to changes in physiological conditions including potassium depletion or loading. This review highlights the potential for targeting these molecular pathways to develop novel therapeutic strategies for the treatment of salt-sensitive hypertension, the mechanism of which remains to be elucidated.
Assuntos
Hipertensão , Néfrons , Humanos , Animais , Néfrons/metabolismo , Hipertensão/fisiopatologia , Hipertensão/metabolismo , Hipertensão/tratamento farmacológico , Transdução de Sinais , Cloreto de Sódio na Dieta/metabolismo , Cloreto de Sódio na Dieta/efeitos adversos , Pressão Sanguínea/efeitos dos fármacos , Sódio/metabolismoRESUMO
Hypertension affects approximately one in two United States adults and sex plays an important role in the pathogenesis of hypertension. The Na+-Cl- cotransporter (NCC), regulated by a kinase network including with-no-lysine kinase (WNK)1 and WNK4, STE20/SPS1-related proline alanine-rich kinase (SPAK), and oxidative stress response 1 (OxSR1), is critical to Na+ reabsorption and blood pressure regulation. Dietary salt differentially modulates NCC in salt-sensitive and salt-resistant rats, in part by modulation of WNK/SPAK/OxSR1 signaling. In this study, we tested the hypothesis that sex-dependent differences in NCC regulation contribute to the development of the salt sensitivity of blood pressure using male and female Sprague-Dawley (SD), Dahl salt-resistant (DSR), and Dahl salt-sensitive (DSS) rats. In normotensive salt-resistant SD and DSR rats, a high-salt diet evoked significant decreases in NCC activity, expression, and phosphorylation. In males, these changes were associated with no change in WNK1 expression, a decrease in WNK4 levels, and suppression of SPAK/OxSR1 expression and phosphorylation. In contrast, in females, there was decreased NCC activity associated with suppression of SPAK/OxSR1 expression and phosphorylation. In hypertensive DSS rats, the ability of females to suppress NCC (in opposition to males) via a SPAK/OxSR1 mechanism likely contributes to their lower magnitude of salt-sensitive hypertension. Collectively, our findings support the existence of sex differences in male versus female rats with NCC regulation during dietary salt intake involving suppression of WNK4 expression in male rats only and the involvement of SPAK/OxSR1 signaling in both males and females.NEW & NOTEWORTHY NCC regulation is sex dependent. In normotensive male and female Sprague-Dawley and Dahl salt-resistant rats, which exhibit dietary Na+-evoked NCC suppression, male rats exhibit decreased WNK4 expression and decreased SPAK and OxSR1 levels, whereas female rats only suppress SPAK and OxSR1. In hypertensive Dahl salt-sensitive rats, the ability of females to suppress NCC (in opposition to males) via a SPAK/OxSR1 mechanism likely contributes to their lower magnitude of salt-sensitive hypertension.
Assuntos
Pressão Sanguínea , Hipertensão , Proteínas Serina-Treonina Quinases , Ratos Endogâmicos Dahl , Ratos Sprague-Dawley , Cloreto de Sódio na Dieta , Membro 3 da Família 12 de Carreador de Soluto , Animais , Feminino , Masculino , Pressão Sanguínea/efeitos dos fármacos , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Membro 3 da Família 12 de Carreador de Soluto/genética , Fatores Sexuais , Fosforilação , Rim/metabolismo , Rim/efeitos dos fármacos , Transdução de Sinais , Ratos , Modelos Animais de DoençasRESUMO
The dietary approach to stop hypertension (DASH) diet combines the antihypertensive effect of a low sodium and high potassium diet. In particular, the potassium component of the diet acts as a switch in the distal convoluted tubule to reduce sodium reabsorption, similar to a diuretic but without the side effects. Previous trials to understand the mechanism of the DASH diet were based on animal models and did not characterize changes in human ion channel protein abundance. More recently, protein cargo of urinary extracellular vesicles (uEVs) has been shown to mirror tissue content and physiological changes within the kidney. We designed an inpatient open label nutritional study transitioning hypertensive volunteers from an American style diet to DASH diet to examine physiological changes in adults with stage 1 hypertension otherwise untreated (Sacks FM, Svetkey LP, Vollmer WM, Appel LJ, Bray GA, Harsha D, Obarzanek E, Conlin PR, Miller ER 3rd, Simons-Morton DG, Karanja N, Lin PH; DASH-Sodium Collaborative Research Group. N Engl J Med 344: 3-10, 2001). Urine samples from this study were used for proteomic characterization of a large range of pure uEVs (small to large) to reveal kidney epithelium changes in response to the DASH diet. These samples were collected from nine volunteers at three time points, and mass spectrometry identified 1,800 proteins from all 27 samples. We demonstrated an increase in total SLC12A3 [sodium-chloride cotransporter (NCC)] abundance and a decrease in aquaporin-2 (AQP2) in uEVs with this mass spectrometry analysis, immunoblotting revealed a significant increase in the proportion of activated (phosphorylated) NCC to total NCC and a decrease in AQP2 from day 5 to day 11. This data demonstrates that the human kidney's response to nutritional interventions may be captured noninvasively by uEV protein abundance changes. Future studies need to confirm these findings in a larger cohort and focus on which factor drove the changes in NCC and AQP2, to which degree NCC and AQP2 contributed to the antihypertensive effect and address if some uEVs function also as a waste pathway for functionally inactive proteins rather than mirroring protein changes.NEW & NOTEWORTHY Numerous studies link DASH diet to lower blood pressure, but its mechanism is unclear. Urinary extracellular vesicles (uEVs) offer noninvasive insights, potentially replacing tissue sampling. Transitioning to DASH diet alters kidney transporters in our stage 1 hypertension cohort: AQP2 decreases, NCC increases in uEVs. This aligns with increased urine volume, reduced sodium reabsorption, and blood pressure decline. Our data highlight uEV protein changes as diet markers, suggesting some uEVs may function as waste pathways. We analyzed larger EVs alongside small EVs, and NCC in immunoblots across its molecular weight range.
Assuntos
Aquaporina 2 , Vesículas Extracelulares , Humanos , Vesículas Extracelulares/metabolismo , Aquaporina 2/metabolismo , Aquaporina 2/urina , Masculino , Feminino , Pessoa de Meia-Idade , Abordagens Dietéticas para Conter a Hipertensão , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Simportadores de Cloreto de Sódio/metabolismo , Hipertensão/dietoterapia , Hipertensão/urina , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Adulto , Dieta Hipossódica , Pressão Sanguínea , Proteômica/métodos , Rim/metabolismoRESUMO
The kidney regulates blood pressure through salt/water reabsorption affected by tubular sodium transporters. Expanding our prior research on placental cluster of differentiation 81 (CD81), this study explores the interaction of renal CD81 with sodium transporters in preeclampsia (PE). Effects of renal CD81 with sodium transporters were determined in lipopolysaccharide (LPS)-induced PE rats and immortalized mouse renal distal convoluted tubule cells. Urinary exosomal CD81, sodium potassium 2 chloride cotransporter (NKCC2), and sodium chloride cotransporter (NCC) were measured in PE patients. LPS-PE rats had hypertension from gestational days (GD) 6 to 18 and proteinuria from GD9 to GD18. Urinary CD81 in both groups tented to rise during pregnancy. Renal CD81, not sodium transporters, was higher in LPS-PE than controls on GD14. On GD18, LPS-PE rats exhibited higher CD81 in kidneys and urine exosomes, higher renal total and phosphorylated renal NKCC2 and NCC with elevated mRNAs, and lower ubiquitinated NCC than controls. CD81 was co-immunoprecipitated with NKCC2 or NCC in kidney homogenates and co-immunostained with NKCC2 or NCC in apical membranes of renal tubules. In plasma membrane fractions, LPS-PE rats had greater amounts of CD81, NKCC2, and NCC than controls with enhanced co-immunoprecipitations of CD81 with NKCC2 or NCC. In renal distal convoluted tubule cells, silencing CD81 with siRNA inhibited NCC and prevented LPS-induced NCC elevation. Further, PE patients had higher CD81 in original urines, urine exosomes and higher NKCC2 and NCC in urine exosomes than controls. Thus, the upregulation of renal CD81 on NKCC2 and NCC may contribute to the sustained hypertension observed in LPS-PE model. Urine CD81 with NKCC2 and NCC may be used as biomarkers for PE.
Assuntos
Hipertensão , Pré-Eclâmpsia , Gravidez , Camundongos , Humanos , Ratos , Feminino , Animais , Simportadores de Cloreto de Sódio-Potássio/metabolismo , Simportadores de Cloreto de Sódio/genética , Simportadores de Cloreto de Sódio/metabolismo , Lipopolissacarídeos/toxicidade , Lipopolissacarídeos/metabolismo , Cloretos/metabolismo , Pré-Eclâmpsia/induzido quimicamente , Pré-Eclâmpsia/metabolismo , Membro 1 da Família 12 de Carreador de Soluto/metabolismo , Placenta/metabolismo , Túbulos Renais Distais/metabolismo , Hipertensão/metabolismo , Sódio/metabolismo , Potássio/metabolismo , Tetraspanina 28/metabolismoRESUMO
Several studies in computer vision have examined specular removal, which is crucial for object detection and recognition. This research has traditionally been divided into two tasks: specular highlight removal, which focuses on removing specular highlights on object surfaces, and reflection removal, which deals with specular reflections occurring on glass surfaces. In reality, however, both types of specular effects often coexist, making it a fundamental challenge that has not been adequately addressed. Recognizing the necessity of integrating specular components handled in both tasks, we constructed a specular-light (S-Light) DB for training single-image-based deep learning models. Moreover, considering the absence of benchmark datasets for quantitative evaluation, the multi-scale normalized cross correlation (MS-NCC) metric, which considers the correlation between specular and diffuse components, was introduced to assess the learning outcomes.
RESUMO
Solute carrier 12 (Slc12) is a family of electroneutral cation-coupled chloride (Cl-) cotransporters. Na+/K+/2Cl- (Nkcc) and Na+/Cl- cotransporters (Ncc) belong to the Nkcc/Ncc subfamily. Human and mouse possess one gene for the Na+/Cl- cotransporter (ncc gene: slc12a3), whereas teleost fishes possess multiple ncc genes, slc12a3 (ncc1) and slc12a10 (ncc2), in addition to their species-specific paralogs. Amphibians and squamates have two ncc genes: slc12a3 (ncc1) and ncc3. However, the evolutionary relationship between slc12a10 and ncc3 remains unresolved, and the presence of slc12a10 (ncc2) in mammals has not been clarified. Synteny and phylogenetic analyses of vertebrate genome databases showed that ncc3 is the ortholog of slc12a10, and slc12a10 is present in most ray-finned fishes, coelacanths, amphibians, reptiles, and a few mammals (e.g., platypus and horse) but pseudogenized or deleted in birds, most mammals, and some ray-finned fishes (pufferfishes). This shows that slc12a10 is widely present among bony vertebrates and pseudogenized or deleted independently in multiple lineages. Notably, as compared with some fish that show varied slc12a10 tissue expression profile, spotted gar, African clawed frog, red-eared slider turtle, and horse express slc12a10 in the ovaries or premature gonads. In horse tissues, an unexpectedly large number of splicing variants for Slc12a10 have been cloned, many of which encode truncated forms of Slc12a10, suggesting that the functional constraints of horse slc12a10 are weakened, which may be in the process of becoming a pseudogene. Our results elaborate on the evolution of Nkcc/Ncc subfamily of Slc12 in vertebrates.NEW & NOTEWORTHY slc12a10 is not a fish-specific gene and is present in a few mammals (e.g., platypus and horse), non-avian reptiles, amphibians, but was pseudogenized or deleted in most mammals (e.g., human, mouse, cat, cow, and rhinoceros), birds, and some ray-finned fishes (pufferfishes).
Assuntos
Ornitorrinco , Feminino , Bovinos , Animais , Humanos , Cavalos , Camundongos , Membro 3 da Família 12 de Carreador de Soluto , Filogenia , Peixes/genética , Répteis/genética , Aves , Anfíbios/genéticaRESUMO
The goal of this study was to investigate the neurophysiological correlates of visual awareness, with a specific focus on its event-related spectral perturbation (ERSP) features. To this aim, we tried to disentangle the proper neural correlates of consciousness (NCC) from other prerequisite and post-perceptual processing. To do so, we administered an orientation discrimination task, inducing a response bias through task instructions. EEG results showed that different frequency bands are involved in this kind of task, with different spectral and temporal dynamics. In particular, alpha and beta bands seem to be particularly engaged, especially in the aware-unaware contrast, showing a main power suppression for aware trials and replicating previous literature. Moreover, we demonstrated that the process of visual awareness is orchestrated by a complex interaction of different frequencies (i.e., theta, alpha, beta and gamma) being involved as prerequisites and post-perceptual processes.
Assuntos
Estado de Consciência , Eletroencefalografia , Estado de Consciência/fisiologia , Motivação , Estimulação Luminosa , Conscientização/fisiologiaRESUMO
The gills are the major organ for Na+ uptake in teleosts. It was proposed that freshwater (FW) teleosts adopt Na+/H+ exchanger 3 (Nhe3) as the primary transporter for Na+ uptake and Na+-Cl- co-transporter (Ncc) as the backup transporter. However, convincing molecular physiological evidence to support the role of Ncc in branchial Na+ uptake is still lacking due to the limitations of functional assays in the gills. Thus, this study aimed to reveal the role of branchial Ncc in Na+ uptake with an in vivo detection platform (scanning ion-selective electrode technique, SIET) that has been recently established in fish gills. First, we identified that Ncc2-expressing cells in zebrafish gills are a specific subtype of ionocyte (NCC ionocytes) by using single-cell transcriptome analysis and immunofluorescence. After a long-term low-Na+ FW exposure, zebrafish increased branchial Ncc2 expression and the number of NCC ionocytes and enhanced gill Na+ uptake capacity. Pharmacological treatments further suggested that Na+ is indeed taken up by Ncc, in addition to Nhe, in the gills. These findings reveal the uptake roles of both branchial Ncc and Nhe under FW and shed light on osmoregulatory physiology in adult fish.
Assuntos
Simportadores , Peixe-Zebra , Animais , Peixe-Zebra/metabolismo , Simportadores/metabolismo , Transporte Biológico , Transporte de Íons/fisiologia , Brânquias/metabolismo , Trocador 3 de Sódio-Hidrogênio/metabolismo , Água DoceRESUMO
Regulated Na+ transport in the distal nephron is of fundamental importance to fluid and electrolyte homeostasis. Further upstream, Na+ is the principal driver of secondary active transport of numerous organic and inorganic solutes. In the distal nephron, Na+ continues to play a central role in controlling the body levels and concentrations of a more select group of ions, including K+, Ca++, Mg++, Cl-, and HCO3-, as well as water. Also, of paramount importance are transport mechanisms aimed at controlling the total level of Na+ itself in the body, as well as its concentrations in intracellular and extracellular compartments. Over the last several decades, the transporters involved in moving Na+ in the distal nephron, and directly or indirectly coupling its movement to that of other ions have been identified, and their interrelationships brought into focus. Just as importantly, the signaling systems and their components-kinases, ubiquitin ligases, phosphatases, transcription factors, and others-have also been identified and many of their actions elucidated. This review will touch on selected aspects of ion transport regulation, and its impact on fluid and electrolyte homeostasis. A particular focus will be on emerging evidence for site-specific regulation of the epithelial sodium channel (ENaC) and its role in both Na+ and K+ homeostasis. In this context, the critical regulatory roles of aldosterone, the mineralocorticoid receptor (MR), and the kinases SGK1 and mTORC2 will be highlighted. This includes a discussion of the newly established concept that local K+ concentrations are involved in the reciprocal regulation of Na+-Cl- cotransporter (NCC) and ENaC activity to adjust renal K+ secretion to dietary intake.
Assuntos
Canais Epiteliais de Sódio , Túbulos Renais Distais , Aldosterona/metabolismo , Eletrólitos/metabolismo , Canais Epiteliais de Sódio/metabolismo , Homeostase , Transporte de Íons , Túbulos Renais Distais/metabolismo , Sódio/metabolismo , Membro 3 da Família 12 de Carreador de Soluto/metabolismoRESUMO
The diagnosis of neurocysticercosis (NCC) depends on neuroimaging and serological confirmation. While antibody detection by enzyme-linked immunoelectrotransfer blot (EITB) fails to predict viable NCC, EITB banding patterns provide information about the host's infection course. Adding antigen enzyme-linked immunosorbent assay (Ag-ELISA) results to EITB banding patterns may improve their ability to predict or rule out of viable NCC. We assessed whether combining EITB banding patterns with Ag-ELISA improves discrimination of viable infection in imaging-confirmed parenchymal NCC. EITB banding patterns were grouped into classes using latent class analysis. True-positive and false-negative Ag-ELISA results in each class were compared using Fisher's exact test. Four classes were identified: 1, EITB negative or positive to GP50 alone (GP50 antigen family); 2, positive to GP42-39 and GP24 (T24/42 family), with or without GP50; and 3 and 4, positive to GP50, GP42-39, and GP24 and reacting to bands in the 8-kDa family. Most cases in classes 3 and 4 had viable NCC (82% and 88%, respectively) compared to classes 2 and 1 (53% and 5%, respectively). Adding positive Ag-ELISA results to class 2 predicted all viable NCC cases (22/22 [100%]), whereas 11/40 patients (27.5%) Ag-ELISA negative had viable NCC (P < 0.001). Only 1/4 patients (25%) Ag-ELISA positive in class 1 had viable NCC, whereas 1/36 patients (2.8%) Ag-ELISA negative had viable NCC (P = 0.192). In classes 3 and 4, adding Ag-ELISA was not contributory. Combining Ag-ELISA with EITB banding patterns improves discrimination of viable from nonviable NCC, particularly for class 2 responses. Together, these complement neuroimaging more appropriately for the diagnosis of viable NCC.
Assuntos
Neurocisticercose , Taenia solium , Animais , Anticorpos Anti-Helmínticos , Antígenos de Helmintos , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Neurocisticercose/diagnóstico , Sensibilidade e EspecificidadeRESUMO
BACKGROUND: Routine measurement of tumor markers is not recommended in daily clinical practice for patients with cancer of unknown primary (CUP). We evaluated the diagnostic value of tumor markers in identifying favorable or unfavorable subsets in patients with CUP. METHODS: We retrospectively reviewed the medical records of patients who were diagnosed with CUP between October 2010 and July 2015 at the National Cancer Center Hospital. The tumor markers of the patients were examined, including squamous cell carcinoma antigen, cytokeratin fraction, carcinoembryonic antigen, sialyl Lewis X, neuron-specific enolase, pro-gastrin-releasing peptide, α-fetoprotein, protein induced by vitamin K absence or antagonist II, prostate-specific antigen, soluble interleukin-2 receptor, carbohydrate antigen 19-9, cancer antigen 125, cancer antigen 15-3, NCC-ST-439 (ST439), elastase-1, human chorionic gonadotropin, and sialyl-Tn (STN). RESULTS: Among 199 patients with suspected CUP, 90 were diagnosed with confirmed CUP (12 in the favorable subset and 78 in the unfavorable subset). No tumor markers showed 100% sensitivity for unfavorable subsets. ST439 (p = 0.03) and STN (p = 0.049) showed 100% specificity for unfavorable subsets. CONCLUSIONS: For patients with suspected CUP who show elevated ST439 or STN levels, the treatment strategy should be based on the premise that the patient is likely to be placed in the unfavorable subset.
Assuntos
Biomarcadores Tumorais , Neoplasias Primárias Desconhecidas , Antígenos Glicosídicos Associados a Tumores , Antígeno CA-19-9 , Antígeno Carcinoembrionário , Humanos , Queratinas , Masculino , Neoplasias Primárias Desconhecidas/patologia , Estudos RetrospectivosRESUMO
BACKGROUND: Sunflower seeds (Helianthus annuus) display an attractive source for the rapidly increasing market of plant-based human nutrition. Of particular interest are press cakes of the seeds, cheap residuals from sunflower oil manufacturing that offer attractive sustainability and economic benefits. Admittedly, sunflower seed milk, derived therefrom, suffers from limited nutritional value, undesired flavor, and the presence of indigestible sugars. Of specific relevance is the absence of vitamin B12. This vitamin is required for development and function of the central nervous system, healthy red blood cell formation, and DNA synthesis, and displays the most important micronutrient for vegans to be aware of. Here we evaluated the power of microbes to enrich sunflower seed milk nutritionally as well as in flavor. RESULTS: Propionibacterium freudenreichii NCC 1177 showed highest vitamin B12 production in sunflower seed milk out of a range of food-grade propionibacteria. Its growth and B12 production capacity, however, were limited by a lack of accessible carbon sources and stimulants of B12 biosynthesis in the plant milk. This was overcome by co-cultivation with Bacillus amyloliquefaciens NCC 156, which supplied lactate, amino acids, and vitamin B7 for growth of NCC 1177 plus vitamins B2 and B3, potentially supporting vitamin B12 production by the Propionibacterium. After several rounds of optimization, co-fermentation of ultra-high-temperature pre-treated sunflower seed milk by the two microbes, enabled the production of 17 µg (100 g)-1 vitamin B12 within four days without any further supplementation. The fermented milk further revealed significantly enriched levels of L-lysine, the most limiting essential amino acid, vitamin B3, vitamin B6, improved protein quality and flavor, and largely eliminated indigestible sugars. CONCLUSION: The fermented sunflower seed milk, obtained by using two food-grade microbes without further supplementation, displays an attractive, clean-label product with a high level of vitamin B12 and multiple co-benefits. The secret of the successfully upgraded plant milk lies in the multifunctional cooperation of the two microbes, which were combined, based on their genetic potential and metabolic signatures found in mono-culture fermentations. This design by knowledge approach appears valuable for future development of plant-based milk products.
Assuntos
Bacillus amyloliquefaciens , Propionibacterium freudenreichii , Animais , Técnicas de Cocultura , Humanos , Leite , Sementes , Vitamina B 12 , Vitaminas/metabolismoRESUMO
Conscious perceptual experiences are expected to correlate with content-specific brain activity. A veridicality problem arises when attempting to disentangle unconscious and conscious brain processes if conscious perceptual contents accurately match the physical nature of the stimulus. We argue that perceptual filling-in, a phenomenon whereby visual information inaccurately spreads across visual space, is a promising approach to circumvent the veridicality problem. Filling-in generates non-veridical although unambiguous percepts dissociated from stimulus input. In particular, the radial uniformity illusion induces a filling-in experience between a central disk and the surrounding periphery. We discuss how this illusion facilitates both the detection of neurophysiological responses and subjective phenomenological monitoring. We report behavioral effects from a large-sample (n = 200) psychophysics study and examine key stimulus parameters that drive the conscious filling-in experience. We propose that these data underpin future hypothesis-driven studies of filling-in to further delineate the neural mechanisms of conscious perception.
Assuntos
Ilusões , Encéfalo/fisiologia , Estado de Consciência/fisiologia , Humanos , Psicofísica , Percepção Visual/fisiologiaRESUMO
The effect of blocking the persistent component of the sodium channel current (late INa) on the automatic activity of the isolated guinea pig pulmonary vein myocardium was examined. NCC-3902 blocked late INa, but did not affect other major ion channel currents stably expressed in cell lines. In isolated pulmonary vein cardiomyocytes, NCC-3902 blocked the late INa induced by a ramp depolarizing voltage clamp pulse similar to that of the pacemaker depolarization observed in the pulmonary vein myocardium. In isolated pulmonary vein tissue, NCC-3902 decreased the frequency of automatic firing of the myocardium through a reduction of the pacemaker depolarization slope. In isolated pulmonary vein cardiomyocytes, NCC-3902 significantly reduced the firing frequency of Ca2+ transients, but had no effect on Ca2+ sparks. NCC-3902 affected neither the spontaneous beating rate of the right atrium nor the contractile force of the ventricular myocardium. Selective blockers of late INa like NCC-3902, which inhibit the automatic activity of the pulmonary vein myocardium, appear to be promising as drugs for the pharmacological treatment of atrial fibrillation.
Assuntos
Veias Pulmonares , Cobaias , Animais , Sódio/metabolismo , Potenciais de Ação , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismoRESUMO
Familial hyperkalemic hypertension (FHHt; also called pseudohypoaldosteronism type II) is a hereditary hypertensive disease which can be caused by mutations in four genes: WNK1 [with no lysine (K) 1], WNK4, Kelch-like3 (KLHL3), and cullin3 (CUL3). Decreased KLHL3 expression was identified as being involved in the pathogenesis of FHHt caused by cullin 3 disease mutations. Recent studies have revealed an increased WNK4 and hence Na-Cl cotransporter (NCC) activity in the db/db mice, resulting from PKC-mediated KLHL3 phosphorylation, which impairs the degradation of its substrate, WNK4. However, whether WNK4 and NCC were activated in type 1 diabetes still remains unclear. We created streptozotocin-induced type 1 diabetic mice and revealed that renal WNK-oxidative stress response kinase-1/STE20/SPS1-related proline alanine-rich kinase (OSR1/SPAK)-NCC cascade was activated, whereas KLHL3 expression was markedly decreased and CUL3 was heavily neddylated. Moreover, decreased KLHL3 was reversed and WNK1 and WNK4 abundance increased by MLN4924, a neddylation inhibitor. In vitro, our study also showed decreased KLHL3 abundance without any significant change in phosphorylated KLHL3 under high glucose exposure. These results indicate that decreased KLHL3 likely plays a role in the pathogenesis of renal sodium reabsorption in hyperglycemic conditions.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/metabolismo , Rim/metabolismo , Proteínas dos Microfilamentos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteína Quinase 1 Deficiente de Lisina WNK/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Glicemia/metabolismo , Pressão Sanguínea , Proteínas Culina/metabolismo , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Tipo 1/induzido quimicamente , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/fisiopatologia , Células HEK293 , Humanos , Rim/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Proteínas dos Microfilamentos/genética , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Reabsorção Renal , Transdução de Sinais , Sódio/metabolismo , Membro 3 da Família 12 de Carreador de Soluto/metabolismo , Estreptozocina , Ubiquitinação , Proteína Quinase 1 Deficiente de Lisina WNK/genéticaRESUMO
We compared the regulation of the NaCl cotransporter (NCC) in adaptation to a low-K (LK) diet in male and female mice. We measured hydrochlorothiazide (HCTZ)-induced changes in urine volume (UV), glomerular filtration rate (GFR), absolute (ENa, EK), and fractional (FENa, FEK) excretion in male and female mice on control-K (CK, 1% KCl) and LK (0.1% KCl) diets for 7 days. With CK, NCC-dependent ENa and FENa were larger in females than males as observed previously. However, with LK, HCTZ-induced ENa and FENa increased in males but not in females, abolishing the sex differences in NCC function as observed in CK group. Despite large diuretic and natriuretic responses to HCTZ, EK was only slightly increased in response to the drug when animals were on LK. This suggests that the K-secretory apparatus in the distal nephron is strongly suppressed under these conditions. We also examined LK-induced changes in Na transport protein expression by Western blotting. Under CK conditions females expressed more NCC protein, as previously reported. LK doubled both total (tNCC) and phosphorylated NCC (pNCC) abundance in males but had more modest effects in females. The larger effect in males abolished the sex-dependence of NCC expression, consistent with the measurements of function by renal clearance. LK intake did not change NHE3, NHE2, or NKCC2 expression, but reduced the amount of the cleaved (presumably active) form of γENaC. LK reduced plasma K to lower levels in females than males. These results indicated that males had a stronger NCC-mediated adaptation to LK intake than females.