RESUMEN
Hormones are specific molecules measured in biological fluids by elaborate analytical systems requiring meticulous attention. Variation between laboratories can be expected. However, recently published measurements of AVP, OXT, and BNP in human plasma under basal/control conditions include numbers which, between publications, vary by 100-10 000-fold. Generally, the methods descriptions are scant, at best, and provide no information about quality control measures. Clearly, two results describing the same basal hormone concentration by numbers three orders of magnitude apart are incongruent providing reason for concern. Basal concentrations of bioactive AVP, OXT, and BNP in human plasma are in the order of 1-10 pmol/L. Therefore, assay systems applied to plasma must be able to measure concentrations of less than 1 pmol/L with appropriate specificity and accuracy. Basal concentrations of AVP, OXT, and BNP above 100 pmol/L should be reconsidered, as such results do not reflect bioactive hormone levels in humans, rats, or mice. Any concentration above 1000 pmol/L is of concern because such levels of bioactive hormone may be seen only under extreme conditions, if at all.
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Péptido Natriurético Encefálico , Oxitocina , Vasopresinas , Humanos , Oxitocina/sangre , Péptido Natriurético Encefálico/sangre , Vasopresinas/sangre , Animales , Hormonas Peptídicas/sangreRESUMEN
BACKGROUND: The mechanisms by which hypertension accelerates coronary artery disease are poorly understood. Patients with hypertension often have confounding humoral changes, and to date, no experimental models have allowed analysis of the isolated effect of pressure on atherosclerosis in a setting that recapitulates the dimensions and biomechanics of human coronary arteries. OBJECTIVES: This study sought to analyze the effect of pressure on coronary atherosclerosis and explore the underlying mechanisms. METHODS: Using inflatable suprarenal aortic cuffs, we increased mean arterial pressure by >30 mm Hg in the cephalad body part of wild-type and hypercholesterolemic proprotein convertase subtilisin kexin type 9 (PCSK9)D374Y Yucatan minipigs for >1 year. Caudal pressures remained normal. RESULTS: Under hypercholesterolemic conditions in PCSK9D374Y transgenic minipigs, cephalad hypertension accelerated coronary atherosclerosis to almost 5-fold with consistent development of fibroatheromas that were sufficiently large to cause stenosis on computed tomography angiography. This was caused by local pressure forces, because vascular beds shielded from hypertension, but exposed to the same humoral factors, showed no changes in lesion formation. The same experiment was conducted under normocholesterolemic conditions in wild-type minipigs to examine the underlying mechanisms. Hypertension produced clear changes in the arterial proteome with increased abundance of mechanical strength proteins and reduced levels of infiltrating plasma macromolecules. This was paralleled by increased smooth muscle cells and increased intimal accumulation of low-density lipoproteins in the coronary arteries. CONCLUSIONS: Increased pressure per se facilitates coronary atherosclerosis. Our data indicate that restructuring of the artery to match increased tensile forces in hypertension alters the passage of macromolecules and leads to increased intimal accumulation of low-density lipoproteins.
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Presión Sanguínea/fisiología , Enfermedad de la Arteria Coronaria/fisiopatología , Hipertensión/fisiopatología , Lipoproteínas LDL/sangre , Flujo Sanguíneo Regional/fisiología , Animales , Animales Modificados Genéticamente , Biomarcadores/sangre , Enfermedad de la Arteria Coronaria/sangre , Enfermedad de la Arteria Coronaria/etiología , Modelos Animales de Enfermedad , Hipertensión/sangre , Hipertensión/complicaciones , Porcinos , Porcinos EnanosRESUMEN
Replicability of experimental results and optimal use of experimental animals are everybody's concern. Current efforts towards increased replicability include guidelines and checklists as tools for experimenters, referees, editors and publishers. Guidelines are also provided for appropriate use of animals. To ensure the quality of experimental results, the number of animals must be adequate, that is, sufficiently large, for the purpose of the given experiment. To comply with current ethical recommendations, the use of animals should be reduced as much as possible. Therefore, determination of the number of animals for a given scientific objective includes contrasting considerations. Current guidelines for animal experimentation, notably from the National Institute of Health, mandate (with very few exceptions) inclusion of animals of both sexes in experimental designs statistically powered to address the difference between the two groups. Notably, absence of evidence for sex differences between the organ or system functions under study does not qualify as an exception. Mandatory, equal representation of both sexes raises several questions including ethical ones. Other guidelines, by public regulators and major publishers, do not seem to have a similar selective focus on sex differences. In summary, current concerns about replicability of scientific results are justified. Concomitantly, the knowledge of sex differences also between non-reproductive, non-endocrine organ functions is increasing. In principle, sex matters in any experimental context. However, an indiscriminate demand for inclusion of both sexes in all experimental protocols seems a waste of animals, money and time, violating traditional principles of animal experimentation, particularly that of reduction.
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Experimentación Animal/normas , Animales de Laboratorio , Proyectos de Investigación/normas , Caracteres Sexuales , Experimentación Animal/ética , Derechos del Animal , Alternativas al Uso de Animales/ética , Alternativas al Uso de Animales/métodos , Alternativas al Uso de Animales/normas , Animales , Femenino , Guías como Asunto , Vivienda para Animales/organización & administración , Vivienda para Animales/normas , MasculinoRESUMEN
AIMS: In patients with essential hypertension, abnormal renal sodium handling includes exaggerated natriuresis in response to extracellular volume expansion. We tested the hypothesis that exaggerated natriuresis is associated with increases in medullary and/or cortical renal blood flow. METHODS: Patients with mild essential hypertension, but no signs of end organ damage, and control subjects were studied after 4 days of dietary standardization (<60 mmol Na+ day-1 ) preceded in patients by a 14-day drug washout period. On the study day, subjects received a 4-hour intravenous volume expansion with saline (2.1% of body mass). Renal medullary and cortical blood flows were measured by PET scanning using H215 O as tracer; anatomical regions of interest were defined by contrast-enhanced CT scanning. RESULTS: In patients, arterial blood pressure increased during volume expansion (107 ± 2-114 ± 3 mm Hg, P < 0.05) in contrast to the control group (92 ± 2-92 ± 2 mm Hg). Renal sodium excretion increased more in patients than in controls (+133 ± 31 µmol min-1 vs +61 ± 14 µmol min-1 , respectively, P < 0.05) confirming exaggerated natriuresis. During volume expansion, renal medullary blood flow did not change significantly in patients (2.8 ± 0.4-2.5 ± 0.5 mL (g tissue)-1 min-1 ) or in controls (3.2 ± 0.3-3.1 ± 0.2 mL (g tissue)-1 min-1 ). In control subjects, renal cortical blood flow fell during volume expansion (4.1 ± 0.3-3.7 ± 0.2 mL (g tissue)-1 min-1 , P < 0.05) in contrast to patients in which deviations remained insignificant. CONCLUSION: Exaggerated natriuresis, a hallmark of essential hypertension, is not mediated by increases in regional, renal blood flow.
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Hipertensión Esencial/fisiopatología , Hipertensión/fisiopatología , Natriuresis/fisiología , Circulación Renal/fisiología , Adulto , Presión Sanguínea/fisiología , Femenino , Tasa de Filtración Glomerular/fisiología , Hemodinámica/fisiología , Humanos , Médula Renal/fisiología , Masculino , Persona de Mediana Edad , Flujo Sanguíneo Regional/fisiologíaRESUMEN
Autoregulation of cerebral blood flow (CBF) denotes that CBF is constant despite fluctuation of blood pressure within wide limits. Inhibition of the renin-angiotensin system (RAS) is known to decrease the lower and upper limits of CBF autoregulation. We have previously shown that this includes inhibition by the angiotensin receptor blocker (ARB) candesartan. In the present study we investigated the influence of the ARB candesartan on the lower limit of CBF autoregulation in two groups of Sprague-Dawley rats, on high (4.0% Na+) and low (0.004% Na+) sodium diet, respectively. Control animals were given the same diet, but no ARB. CBF was studied with the laser Doppler method. Blood pressure was lowered by controlled bleeding. Results revealed that both high and low sodium diet with low and high renin levels respectively block the influence of candesartan on CBF autoregulation. This was expected in rats on a high salt diet with a low renin level, but unexpected in rats with a low salt intake with a high renin level.
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Bloqueadores del Receptor Tipo 1 de Angiotensina II/farmacología , Bencimidazoles/farmacología , Circulación Cerebrovascular/efectos de los fármacos , Dieta Hiposódica , Homeostasis/efectos de los fármacos , Sodio en la Dieta/administración & dosificación , Tetrazoles/farmacología , Animales , Compuestos de Bifenilo , Presión Sanguínea/efectos de los fármacos , Masculino , Ratas , Ratas Sprague-Dawley , ReninaRESUMEN
The classical concepts of human sodium balance include 1) a total pool of Na+ of ≈4,200 mmol (total body sodium, TBS) distributed primarily in the extracellular fluid (ECV) and bone, 2) intake variations of 0.03 to ≈6 mmol·kg body mass-1·day-1, 3) asymptotic transitions between steady states with a halftime (T½) of 21 h, 4) changes in TBS driven by sodium intake measuring ≈1.3 day [ΔTBS/Δ(Na+ intake/day)], 5) adjustment of Na+ excretion to match any diet thus providing metabolic steady state, and 6) regulation of TBS via controlled excretion (90-95% renal) mediated by surrogate variables. The present focus areas include 1) uneven, nonosmotic distribution of increments in TBS primarily in "skin," 2) long-term instability of TBS during constant Na+ intake, and 3) physiological regulation of renal Na+ excretion primarily by neurohumoral mechanisms dependent on ECV rather than arterial pressure. Under physiological conditions 1) the nonosmotic distribution of Na+ seems conceptually important, but quantitatively ill defined; 2) long-term variations in TBS represent significant deviations from steady state, but the importance is undetermined; and 3) the neurohumoral mechanisms of sodium homeostasis competing with pressure natriuresis are essential for systematic analysis of short-term and long-term regulation of TBS. Sodium homeostasis and blood pressure regulation are intimately related. Real progress is slow and will accelerate only through recognition of the present level of ignorance. Nonosmotic distribution of sodium, pressure natriuresis, and volume-mediated regulation of renal sodium excretion are essential intertwined concepts in need of clear definitions, conscious models, and future attention.
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Homeostasis/fisiología , Natriuresis/fisiología , Sodio/metabolismo , Equilibrio Hidroelectrolítico/fisiología , Animales , Transporte Biológico/fisiología , Líquidos Corporales/fisiología , Humanos , Sistema Renina-Angiotensina/fisiologíaRESUMEN
Natriuretic peptides are structurally related, functionally diverse hormones. Circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) are delivered predominantly by the heart. Two C-type natriuretic peptides (CNPs) are paracrine messengers, notably in bone, brain, and vessels. Natriuretic peptides act by binding to the extracellular domains of three receptors, NPR-A, NPR-B, and NPR-C of which the first two are guanylate cyclases. NPR-C is coupled to inhibitory proteins. Atrial wall stress is the major regulator of ANP secretion; however, atrial pressure changes plasma ANP only modestly and transiently, and the relation between plasma ANP and atrial wall tension (or extracellular volume or sodium intake) is weak. Absence and overexpression of ANP-related genes are associated with modest blood pressure changes. ANP augments vascular permeability and reduces vascular contractility, renin and aldosterone secretion, sympathetic nerve activity, and renal tubular sodium transport. Within the physiological range of plasma ANP, the responses to step-up changes are unimpressive; in man, the systemic physiological effects include diminution of renin secretion, aldosterone secretion, and cardiac preload. For BNP, the available evidence does not show that cardiac release to the blood is related to sodium homeostasis or body fluid control. CNPs are not circulating hormones, but primarily paracrine messengers important to ossification, nervous system development, and endothelial function. Normally, natriuretic peptides are not powerful natriuretic/diuretic hormones; common conclusions are not consistently supported by hard data. ANP may provide fine-tuning of reno-cardiovascular relationships, but seems, together with BNP, primarily involved in the regulation of cardiac performance and remodeling. © 2017 American Physiological Society. Compr Physiol 8:1211-1249, 2018.
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Líquidos Corporales/fisiología , Péptidos Natriuréticos/metabolismo , Equilibrio Hidroelectrolítico/fisiología , Animales , Biomarcadores , Homeostasis , HumanosRESUMEN
To test the hypothesis that use of oral contraceptives (OC) changes diurnal variation in fluid balance mechanisms including blood pressure, secretion of vasopressin and oxytocin, and renal water and electrolyte excretion. Fifteen naturally cycling (NC) women in mid-follicular phase and 11 long-term OC users were included in a 24-h standardized inpatient study for measurements of vasopressin, oxytocin, sodium, and osmolality in plasma as well as urinary excretion of electrolytes, aquaporin-2, and prostaglandin E2. Blood pressure and heart rate were monitored noninvasively. Plasma vasopressin showed circadian rhythm (P = 0.02) and were similar in both groups (P = 0.18) including nighttime increases (P < 0.001). There was no circadian rhythm in plasma oxytocin within (P = 0.84) or between groups (P = 0.22). OC users had significantly lower plasma osmolality (Δosm: 3.05 ± 0.29 mosm/kg, P = 0.04) and lower plasma sodium (ΔNa+: 0.91 ± 0.09 mmol/l, P = 0.05). The two groups showed similar nighttime decreases in diuresis (1.08 ± 0.04 mL/(kg·h), P < 0.001) and increases in urine osmolality (109 ± 9 mosm/kg, P = 0.02), but similar rates of excretion of Aquaporin-2, prostaglandin E2 and sodium. Nighttime decreases in mean arterial pressure of approximately 13% were significant in both groups (P < 0.001), but 24-h average mean arterial pressure was significantly higher in OC users than in controls (+4.7 ± 0.4 mmHg, P = 0.02). Packed cell volumes were similar between groups (P = 0.54). OC does not change the diurnal patterns of renal fluid excretion, but resets the osmoreceptors for vasopressin release and leads to a significant increase in arterial blood pressure.
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Ritmo Circadiano , Anticonceptivos Orales/farmacología , Riñón/fisiología , Equilibrio Hidroelectrolítico , Adulto , Acuaporina 2/orina , Presión Sanguínea , Estudios de Casos y Controles , Dinoprostona/orina , Diuresis , Femenino , Humanos , Riñón/efectos de los fármacos , Oxitocina/sangre , Sodio/sangre , Sodio/orina , Vasopresinas/sangreRESUMEN
Sodium retention in cirrhosis is associated with changes in the renin-angiotensin-aldosterone system (RAAS), the sympathetic nervous system (SNS), and the glomerular filtration rate (GFR). We hypothesized that in cirrhosis the acute reactions of RAAS and SNS to volume expansion are qualitatively intact, but occurring from elevated baseline levels. Acute cardiovascular, neurohumoral and renal responses to central blood volume changes were studied in cirrhotic patients and healthy controls. In patients, baseline plasma renin concentration (PRC) was elevated 5-fold compared to controls (p < .001); it increased during standing (+144%, p < .001) and remained elevated during subsequent sitting (+118%, p < .001). At baseline, plasma angiotensin II (pANGII) was not elevated significantly (14 ± 2 vs. 9 ± 2 pg/mL) in contrast to plasma aldosterone (pAldo, +160%, p < .001). During orthostatic RAAS activation, the rise in pAngII per unit increase in PRC was 0.04 pg AngII/mIU and 0.48 pg AngII/mIU in patients and controls, respectively (p < .001); similarly, the change in pAldo per unit change in pANGII was 3.6 in patients and 14.5 pg/pg in controls (p < .001). Plasma noradrenaline was elevated in the patients, but the dynamic changes were virtually identical to those of controls. During standing, abrupt decreases in renal blood flow (-63%, p < .001) and GFR (-42% p < .04) occurred only in patients. In conclusion, in stable cirrhosis, static and dynamic dysregulation exists within the RAAS; in the supine position pAngII levels are inappropriately low, and the AngII-mediated regulation of aldosterone secretion is severely impeded. In cirrhotic patients, profound reductions in renal blood flow and GFR occur during standing.
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Cirrosis Hepática/fisiopatología , Sistema Renina-Angiotensina , Adulto , Aldosterona/sangre , Angiotensina II/sangre , Presión Sanguínea , Estudios de Casos y Controles , Creatinina/orina , Femenino , Tasa de Filtración Glomerular , Frecuencia Cardíaca , Hemodinámica , Humanos , Riñón/fisiopatología , Cirrosis Hepática/sangre , Masculino , Persona de Mediana EdadRESUMEN
It was hypothesized that primary renal sodium retention blunted the reactivity of the renin-angiotensin-aldosterone system to changes in salt intake in preeclampsia (PE). A randomized, cross-over, double-blinded, dietary intervention design was used to measure the effects of salt tablets or placebo during low-salt diet in PE patients (n = 7), healthy pregnant women (n = 15), and nonpregnant women (n = 13). High-salt intake decreased renin and angiotensin II concentrations significantly in healthy pregnant women (P < .03) and in nonpregnant women (P < .001), but not in PE (P = .58), while decreases in aldosterone and increases in brain natriuretic peptid (BNP) were similar in the groups. In PE patients, uterine and umbilical artery indices were not adversely changed during low-salt diet. Creatinine clearance was significantly lower in PE with no change by salt intake. PE patients displayed alterations of plasma renin and angiotensin II in response to changes in dietary salt intake compatible with a primary increase in renal sodium reabsorption in hypertensive pregnancies.
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Aldosterona/metabolismo , Canales Epiteliales de Sodio/efectos de los fármacos , Preeclampsia/dietoterapia , Sistema Renina-Angiotensina/efectos de los fármacos , Cloruro de Sodio Dietético/efectos adversos , Adulto , Aldosterona/sangre , Angiotensina II/sangre , Determinación de la Presión Sanguínea , Creatinina/sangre , Dieta Hiposódica , Método Doble Ciego , Femenino , Humanos , Preeclampsia/orina , Embarazo , Reabsorción Renal , Renina/sangre , Cloruro de Sodio Dietético/metabolismo , Arteria Uterina/fisiologíaRESUMEN
BACKGROUND: Variation in the carboxylesterase 1 gene (CES1) may contribute to the efficacy of ACEIs. Accordingly, we examined the impact of CES1 variants on plasma angiotensin II (ATII)/angiotensin I (ATI) ratio in patients with congestive heart failure (CHF) that underwent ACEI dose titrations. Five of these variants have previously been associated with drug response or increased CES1 expression, i.e., CES1 copy number variation, the variant of the duplicated CES1 gene with high transcriptional activity, rs71647871, rs2244613, and rs3815583. Additionally, nine variants, representatives of CES1Var, and three other CES1 variants were examined. METHODS: Patients with CHF, and clinical indication for ACEIs were categorized according to their CES1 genotype. Differences in mean plasma ATII/ATI ratios between genotype groups after ACEI dose titration, expressed as the least square mean (LSM) with 95% confidence intervals (CIs), were assessed by analysis of variance. RESULTS: A total of 200 patients were recruited and 127 patients (63.5%) completed the study. The mean duration of the CHF drug dose titration was 6.2 (SD 3.6) months. After ACEI dose titration, there was no difference in mean plasma ATII/ATI ratios between subjects with the investigated CES1 variants, and only one previously unexplored variation (rs2302722) qualified for further assessment. In the fully adjusted analysis of effects of rs2302722 on plasma ATII/ATI ratios, the difference in mean ATII/ATI ratio between the GG genotype and the minor allele carriers (GT and TT) was not significant, with a relative difference in LSMs of 0.67 (95% CI 0.43-1.07; P = 0.10). Results of analyses that only included enalapril-treated patients remained non-significant after Bonferroni correction for multiple parallel comparisons (difference in LSM 0.60 [95% CI 0.37-0.98], P = 0.045). CONCLUSION: These findings indicate that the included single variants of CES1 do not significantly influence plasma ATII/ATI ratios in CHF patients treated with ACEIs and are unlikely to be primary determinants of ACEI efficacy.
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Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300â mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38â kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4â lâ min(-1), respectively. End-diastolic and end-systolic volumes were 521±61â ml and 228±42â ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59â mlâ kg(-1). Left ventricular circumferential wall stress was 7.83±1.76â kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output.
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Gasto Cardíaco , Jirafas/fisiología , Volumen Sistólico , Función Ventricular , Animales , Presión Sanguínea , Ecocardiografía/veterinaria , MasculinoRESUMEN
The "Guytonian paradigm" places the direct effect of arterial pressure, on renal excretion of salt and water, at the center of long-term control of blood pressure, and thus the pathogenesis of hypertension. It originated in the sixties and remains influential within the field of hypertension research. However, the concept of one central long-term feedback loop, through which arterial pressure is maintained by its influence on renal function, has been questioned. Furthermore, some concepts in the paradigm are undermined by experimental observations. For example, volume retention and increased cardiac output induced by high salt intake do not necessarily lead to increased arterial pressure. Indeed, in multiple models of salt-sensitive hypertension the major abnormality appears to be failure of the vasodilator response to increased cardiac output, seen in salt-resistant animals, rather than an increase in cardiac output itself. There is also evidence that renal control of extracellular fluid volume is driven chiefly by volume-dependent neurohumoral control mechanisms rather than through direct or indirect effects of changes in arterial pressure, compatible with the concept that renal sodium excretion is controlled by parallel actions of different feedback systems, including hormones, reflexes, and renal arterial pressure. Moreover, we still do not fully understand the sequence of events underlying the phenomenon of "whole body autoregulation." Thus the events by which volume retention may develop to hypertension characterized by increased peripheral resistance remain enigmatic. Finally, by definition, animal models of hypertension are not "essential hypertension;" progress in our understanding of essential hypertension depends on new results on system functions in patients.
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Presión Arterial , Hipertensión/fisiopatología , Riñón/fisiopatología , Modelos Cardiovasculares , Natriuresis , Equilibrio Hidroelectrolítico , Animales , Modelos Animales de Enfermedad , Retroalimentación Fisiológica , Humanos , Hipertensión/metabolismo , Riñón/metabolismoAsunto(s)
Trasplante de Riñón , Riñón/metabolismo , Mitocondrias/metabolismo , Oxígeno/metabolismo , Animales , MasculinoRESUMEN
Voltage-gated Ca(2+) (Cav) channels play an essential role in the regulation of renal blood flow and glomerular filtration rate (GFR). Because T-type Cav channels are differentially expressed in pre- and postglomerular vessels, it was hypothesized that they impact renal blood flow and GFR differentially. The question was addressed with the use of two T-type Cav knockout (Cav3.1(-/-) and Cav3.2(-/-)) mouse strains. Continuous recordings of blood pressure and heart rate, para-aminohippurate clearance (renal plasma flow), and inulin clearance (GFR) were performed in conscious, chronically catheterized, wild-type (WT) and Cav3.1(-/-) and Cav3.2(-/-) mice. The contractility of afferent and efferent arterioles was determined in isolated perfused blood vessels. Efferent arterioles from Cav3.2(-/-) mice constricted significantly more in response to a depolarization compared with WT mice. GFR was increased in Cav3.2(-/-) mice with no significant changes in renal plasma flow, heart rate, and blood pressure. Cav3.1(-/-) mice had a higher renal plasma flow compared with WT mice, whereas GFR was indistinguishable from WT mice. No difference in the concentration response to K(+) was observed in isolated afferent and efferent arterioles from Cav3.1(-/-) mice compared with WT mice. Heart rate was significantly lower in Cav3.1(-/-) mice compared with WT mice with no difference in blood pressure. T-type antagonists significantly inhibited the constriction of human intrarenal arteries in response to a small depolarization. In conclusion, Cav3.2 channels support dilatation of efferent arterioles and affect GFR, whereas Cav3.1 channels in vivo contribute to renal vascular resistance. It is suggested that endothelial and nerve localization of Cav3.2 and Cav3.1, respectively, may account for the observed effects.
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Canales de Calcio Tipo T/fisiología , Tasa de Filtración Glomerular/efectos de los fármacos , Circulación Renal/fisiología , Flujo Plasmático Renal/efectos de los fármacos , Animales , Arteriolas/efectos de los fármacos , Canales de Calcio Tipo T/efectos de los fármacos , Femenino , Humanos , Inulina , Masculino , Ratones , Ratones Noqueados , Resistencia Vascular/efectos de los fármacos , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacos , Ácido p-AminohipúricoRESUMEN
OBJECTIVES: To study the role of microRNAs in hypertension-induced vascular pathology before the onset of symptoms of severe cardiovascular disease. BACKGROUND: MicroRNAs play a crucial role in cardiovascular disease. However, microRNAs are often studied in full-blown cardiovascular disease models, not during development of cardiovascular pathology. METHODS: Angiotensin II was infused into healthy adult rats, inducing chronic hypertension, and microRNA expression profiles were obtained. The most prominently regulated microRNA, miR-487b, was further investigated, using primary cultures of rat aortic and human umbilical cord arterial cells. RESULTS: MiR-487b is predicted to target insulin receptor substrate 1 (IRS1). IRS1 plays an important role in both insulin signaling and cell proliferation and survival. IRS1 mRNA and protein levels were downregulated in aortae of hypertensive rats. MiR-487b binds directly to both rat and human IRS1 3'UTR and inhibits reporter gene expression in vitro. In primary rat and human arterial adventitial fibroblasts, inhibition of miR-487b leads to upregulation of IRS1 expression. Upregulation of miR-487b had the opposite effect, confirming direct targeting of IRS1 by miR-487b.Immunohistochemistry of aortic cross sections and rt/qPCR analyses of the separate aortic wall layers showed that both IRS1 and miR-487b were present mainly in the adventitia and less or not at all in the intima and tunica media. IRS1 expression in adventitial fibroblasts was predominantly nuclear and nuclear IRS1 is known to have antiapoptotic effects. Indeed, inhibition of miR-487b protected adventitial fibroblasts, and also medial smooth muscle cells, against serum starvation-induced apoptosis and increased cell survival. CONCLUSIONS: Angiotensin II-induced hypertension leads to upregulation of miR-487b, which targets IRS1. Via downregulation of IRS1, miR-487b can contribute to cell death and loss of adventitial and medial integrity during hypertension-induced vascular pathology.
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Aorta/metabolismo , Hipertensión/metabolismo , Proteínas Sustrato del Receptor de Insulina/metabolismo , MicroARNs/metabolismo , Angiotensina II/farmacología , Animales , Aorta/patología , Apoptosis , Western Blotting , Proliferación Celular , Supervivencia Celular , Femenino , Fibroblastos/metabolismo , Glucosa/metabolismo , Humanos , Hipertensión/patología , Inmunohistoquímica , Luciferasas/metabolismo , Ratas , Ratas Sprague-Dawley , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de Señal , Células Tumorales Cultivadas , Cordón Umbilical/irrigación sanguíneaRESUMEN
BACKGROUND: Early mobilization is important for postoperative recovery but is limited by orthostatic intolerance (OI) with a prevalence of 50% 6 h after major surgery. The pathophysiology of postoperative OI is assumed to include hypovolemia besides dysregulation of vasomotor tone. Stroke volume-guided fluid therapy, so-called goal-directed therapy (GDT), corrects functional hypovolemia, and the authors hypothesized that GDT reduces the prevalence of OI after major surgery and assessed this in a prospective, double-blinded trial. METHODS: Forty-two patients scheduled for open radical prostatectomy were randomized into standard fluid therapy (control group) or GDT groups. Both groups received a fixed-volume crystalloid regimen supplemented with 1:1 replacement of blood loss with colloid, and in addition, the GDT group received colloid to obtain a maximal stroke volume (esophageal Doppler). The primary outcome was the prevalence of OI assessed with a standardized mobilization protocol before and 6 h after surgery. Hemodynamic and hormonal orthostatic responses were evaluated. RESULTS: Twelve (57%) versus 15 (71%) patients in the control and GDT groups (P = 0.33), respectively, demonstrated OI after surgery, group difference 14% (CI, -18 to 45%). Patients in the GDT group received more colloid during surgery (1,758 vs. 1,057 ml; P = 0.001) and reached a higher stroke volume (102 vs. 89 ml; P = 0.04). OI patients had an increased length of hospital stay (3 vs. 2 days; P = 0.02) and impaired hemodynamic and norepinephrine responses on mobilization. CONCLUSION: GDT did not reduce the prevalence of OI, and patients with OI demonstrated impaired cardiovascular and hormonal responses to mobilization.