Renal responses to hypoxemia during renin-angiotensin system inhibition in fetal lambs

1985 ◽  
Vol 249 (1) ◽  
pp. R116-R124 ◽  
Author(s):  
K. T. Nakamura ◽  
N. A. Ayres ◽  
R. A. Gomez ◽  
J. E. Robillard
Keyword(s):  
Renin Angiotensin System ◽  
Base Line ◽  
Urinary Flow ◽  
Ang Ii ◽  
Functional Responses ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood ◽  
Renal Hemodynamic ◽  
Excretion Rates

The role of the renin-angiotensin system (RAS) in modulating the renal hemodynamic and functional responses to hypoxemia was studied in chronically catheterized fetal lambs (132-143 days gestation; term 145 days) before and during administration of either captopril or [Sar1-Gly8]ANG II. Base-line mean arterial blood pressure decreased significantly after administration of either captopril or [Sar1-Gly8]ANG II. This decrease was associated with a significant decline in renal vascular resistance (RVR) in captopril-treated fetuses, whereas no changes in RVR were observed in [Sar1-Gly8]ANG II-treated fetuses. However, the decline in renal blood flow (RBF) and the rise in RVR associated with hypoxemia in control fetuses were not attenuated significantly during inhibition of the RAS using either captopril or [Sar1-Gly8]ANG II. Moreover neither captopril nor [Sar1-Gly8]ANG II blunted the hypertensive response associated with fetal hypoxemia. The renal functional response to captopril was different from the response observed during infusion of [Sar1-Gly8]ANG II. Administration of [Sar1-Gly8]ANG II produced significant decreases in urinary flow rate (UFR), glomerular filtration rate (GFR), and urinary electrolyte (Na+, K+, Cl-) excretion rates, whereas no changes were observed during captopril infusion. The effects of hypoxemia on renal function were not modified after captopril. However, [Sar1-Gly8]ANG II tended to increase UFR and GFR, but these changes were pressure-dependent and not directly related to inhibition of the RAS. This study suggests that the RAS is not an important mediator of the fetal renal hemodynamic and functional responses to hypoxemia.

Role of angiotensin in sodium appetite of sodium-deplete sheep

1987 ◽  
Vol 253 (3) ◽  
pp. R482-R488 ◽  
Author(s):  
R. S. Weisinger ◽  
D. A. Denton ◽  
R. Di Nicolantonio ◽  
M. J. McKinley ◽  
A. F. Muller ◽  
...  
Keyword(s):  
Intravenous Infusion ◽  
Extracellular Fluid ◽  
Renin Angiotensin System ◽  
Brain Barrier ◽  
Base Line ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood

The role of the renin-angiotensin system (RAS) in the Na appetite of Na-deplete sheep was investigated. Intravenous infusion of the angiotensin-converting enzyme inhibitor, captopril, at 0.01 or 0.1 mg X kg-1 X h-1 did not cause any change in Na intake, although the higher dose caused a marked decrease in mean arterial blood pressure. Intravenous infusion of captopril at 1.0 mg X kg-1 X h-1 over 24 h decreased Na intake by 45-55% in the absence of any change in Na loss. The decrease in Na intake was restored to base-line level or above by concurrent intravenous infusion of angiotensin II (ANG II) at 3.8 or 24 micrograms/h over 24 h but not by intracerebroventricular (ICV) ANG II at 3.8 micrograms/h. In addition, ICV infusion of 0.7 M mannitol (1 ml/h over 3 h), which reduced cerebrospinal fluid (CSF) and brain extracellular fluid [Na], still increased Na intake when combined with intravenous captopril. Water intake was not altered during intravenous captopril or ANG II alone but was increased during ICV ANG II or 0.7 M mannitol (with or without iv captopril). In conclusion, these results suggest that the RAS is involved in the Na appetite of the Na-deplete sheep. Furthermore, it would appear that the brain area involved is one without a blood-brain barrier but with a CSF-brain barrier, such as one of the circumventricular organs. Also, it would appear that the effect of lowered cerebral Na and the effect of activation of the renin-angiotensin system on Na appetite are independent.

scholarly journals Role of renin-angiotensin system in hypotension-evoked thirst: studies with hydralazine

2000 ◽  
Vol 279 (2) ◽  
pp. R576-R585 ◽  
Author(s):  
Sean D. Stocker ◽  
Alan F. Sved ◽  
Edward M. Stricker
Keyword(s):  
Water Intake ◽  
Intravenous Infusion ◽  
Drinking Behavior ◽  
Regression Line ◽  
Renin Angiotensin System ◽  
Ang Ii ◽  
Systemic Injection ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood

Injection of rats either with diazoxide (25 mg/kg iv), isoproterenol (0.33 mg/kg sc), or hydralazine (HDZ) (10 mg/kg ip) decreased arterial blood pressure from ∼120 to 70–80 mmHg and stimulated renin secretion. However, diazoxide and isoproterenol treatments each stimulated water ingestion, whereas HDZ treatment did not. HDZ treatment did not reduce water intake evoked by systemic injection of hypertonic saline or 20% polyethylene glycol solution or by 24-h water deprivation, suggesting that HDZ treatment did not interfere with drinking behavior. In contrast, HDZ treatment markedly reduced water intake evoked by injection of diazoxide or isoproterenol or by intravenous infusion of renin. Furthermore, a highly significant correlation was observed when plasma ANG II levels were plotted as a function of plasma renin activity after intravenous infusion of renin and after diazoxide and isoproterenol treatments. However, values obtained after HDZ treatment alone or in combination with intravenous infusion of renin did not fall near the 99% confidence interval of the regression line, suggesting that HDZ treatment blocks ANG II production and/or promotes its clearance. Thus rats apparently do not increase water intake after HDZ treatment, because this drug interferes with the renin-angiotensin system. These results provide further evidence that arterial hypotension evokes thirst in rats predominantly by activation of the renin-angiotensin system.

Role of the renin-angiotensin system in drinking of seawater-adapted eels Anguilla japonica: a reevaluation

2000 ◽  
Vol 279 (3) ◽  
pp. R1105-R1111 ◽  
Author(s):  
Yoshio Takei ◽  
Takamasa Tsuchida
Keyword(s):  
Arterial Pressure ◽  
Plasma Osmolality ◽  
Renin Angiotensin System ◽  
Minor Role ◽  
Dependent Manner ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood

The role of ANG II, a potent dipsogenic hormone, in copious drinking of seawater eels was examined. SQ-14225 (SQ), an angiotensin-converting enzyme inhibitor, infused intra-arterially at 0.01–1 μg · kg−1 · min−1, depressed drinking and arterial blood pressure in a dose-dependent manner. The inhibition was accompanied by a small decrease in plasma ANG II concentration, which became significant at 1 μg · kg−1 · min−1. After the infusate was changed back to the vehicle, the depression of drinking and arterial pressure continued for >2 h, although plasma ANG II concentration rebounded above the level before SQ infusion. By contrast, infusion of anti-ANG II serum (0.01–1 μg · kg−1 · min−1) did not suppress drinking and arterial pressure, although plasma ANG II concentration decreased to undetectable levels. Plasma atrial natriuretic peptide and plasma osmolality, which influence drinking rate in eels, did not change during SQ or antiserum infusions. These results suggest that the renin-angiotensin system plays only a minor role in the vigorous drinking observed in seawater eels. The results also suggest that the antidipsogenic and vasodepressor effects of SQ in seawater eels are not due solely to the inhibition of ANG II formation in plasma.

Terlipressin Versus  Norepinephrine to Correct Refractory Arterial Hypotension after General Anesthesia in Patients Chronically Treated with Renin-Angiotensin System Inhibitors

2003 ◽  
Vol 98 (6) ◽  
pp. 1338-1344 ◽  
Author(s):  
Gilles Boccara ◽  
Alexandre Ouattara ◽  
Gilles Godet ◽  
Eric Dufresne ◽  
Michèle Bertrand ◽  
...  
Keyword(s):  
Blood Pressure ◽  
General Anesthesia ◽  
Arterial Blood Pressure ◽  
Renin Angiotensin System ◽  
Arterial Hypotension ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood ◽  
Long Term Treatment ◽  
Systolic Arterial Blood Pressure

Background Terlipressin, a precursor that is metabolized to lysine-vasopressin, has been proposed as a drug for treatment of intraoperative arterial hypotension refractory to ephedrine in patients who have received long-term treatment with renin-angiotensin system inhibitors. The authors compared the effectiveness of terlipressin and norepinephrine to correct hypotension in these patients. Methods Among 42 patients scheduled for elective carotid endarterectomy, 20 had arterial hypotension following general anesthesia that was refractory to ephedrine. These patients were the basis of the study. After randomization, they received either 1 mg intravenous terlipressin (n = 10) or norepinephrine infusion (n = 10). Beat-by-beat recordings of systolic arterial blood pressure and heart rate were stored on a computer. The intraoperative maximum and minimum values of blood pressure and heart rate, and the time spent with systolic arterial blood pressure below 90 mmHg and above 160 mmHg, were used as indices of hemodynamic stability. Data are expressed as median (95% confidence interval). Results Terlipressin and norepinephrine corrected arterial hypotension in all cases. However, time spent with systolic arterial blood pressure below 90 mmHg was less in the terlipressin group (0 s [0-120 s] vs. 510 s [120-1011 s]; P < 0.001). Nonresponse to treatment (defined as three boluses of terlipressin or three changes in norepinephrine infusion) occurred in zero and eight cases (P < 0.05), respectively. Conclusions In patients who received long-term treatment with renin-angiotensin system inhibitors, intraoperative refractory arterial hypotension was corrected with both terlipressin and norepinephrine. However, terlipressin was more rapidly effective for maintaining normal systolic arterial blood pressure during general anesthesia.

scholarly journals A novel role for miR-133a in centrally mediated activation of the renin-angiotensin system in congestive heart failure

2017 ◽  
Vol 312 (5) ◽  
pp. H968-H979 ◽  
Author(s):  
Neeru M. Sharma ◽  
Shyam S. Nandi ◽  
Hong Zheng ◽  
Paras K. Mishra ◽  
Kaushik P. Patel
Keyword(s):  
Heart Failure ◽  
Congestive Heart Failure ◽  
Paraventricular Nucleus ◽  
Renin Angiotensin System ◽  
Luciferase Reporter ◽  
Mrna Levels ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin

An activated renin-angiotensin system (RAS) within the central nervous system has been implicated in sympathoexcitation during various disease conditions including congestive heart failure (CHF). In particular, activation of the RAS in the paraventricular nucleus (PVN) of the hypothalamus has been recognized to augment sympathoexcitation in CHF. We observed a 2.6-fold increase in angiotensinogen (AGT) in the PVN of CHF. To elucidate the molecular mechanism for increased expression of AGT, we performed in silico analysis of the 3′-untranslated region (3′-UTR) of AGT and found a potential binding site for microRNA (miR)-133a. We hypothesized that decreased miR-133a might contribute to increased AGT in the PVN of CHF rats. Overexpression of miR-133a in NG108 cells resulted in 1.4- and 1.5-fold decreases in AGT and angiotensin type II (ANG II) type 1 receptor (AT1R) mRNA levels, respectively. A luciferase reporter assay performed on NG108 cells confirmed miR-133a binding to the 3′-UTR of AGT. Consistent with these in vitro data, we observed a 1.9-fold decrease in miR-133a expression with a concomitant increase in AGT and AT1R expression within the PVN of CHF rats. Furthermore, restoring the levels of miR-133a within the PVN of CHF rats with viral transduction resulted in a significant reduction of AGT (1.4-fold) and AT1R (1.5-fold) levels with a concomitant decrease in basal renal sympathetic nerve activity (RSNA). Restoration of miR-133a also abrogated the enhanced RSNA responses to microinjected ANG II within the PVN of CHF rats. These results reveal a novel and potentially unique role for miR-133a in the regulation of ANG II within the PVN of CHF rats, which may potentially contribute to the commonly observed sympathoexcitation in CHF. NEW & NOTEWORTHY Angiotensinogen (AGT) expression is upregulated in the paraventricular nucleus of the hypothalamus through posttranscriptional mechanism interceded by microRNA-133a in heart failure. Understanding the mechanism of increased expression of AGT in pathological conditions leading to increased sympathoexcitation may provide the basis for the possible development of new therapeutic agents with enhanced specificity.

scholarly journals The Biochemical Effects of Angiotensin-(1-7) on the Oxidative Stress Metabolism and Their Specific Parameters from the Temporal Lobe

2020 ◽  
Vol 71 (6) ◽  
pp. 307-311
Author(s):  
Sorin Ungurianu ◽  
Constantin Trus ◽  
Roxana-Rosmary Enciu
Keyword(s):  
Oxidative Stress ◽  
Temporal Lobe ◽  
Renin Angiotensin System ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Angiotensin Peptides ◽  
Vascular Area ◽  
Ang Iv ◽  
The One

It is already known from a variety of previous reports that an independent brain renin�angiotensin system (RAS) exists, completely separated from the one in the periphery. This independent brain RAS has all the precursors and the enzymatic structures necessary for the generation of the angiotensin peptides. Thus, in the last few years various groups started focusing on the more central effects of less known angiotensins (e.g in comparison with Angiotensin (Ang) II), namely Ang III, Ang IV, Ang-(1�7) or Ang 5-8. One of these newly emerging angiotensins which has become an increased center of interest in many studies is Ang-(1-7), which is a heptapeptide previously described especially for its opposite effects to Ang II, in the peripheral vascular area, but also described for some opposite central functions vs. Ang II. These aspects are completed with the fact that it was recently suggested that the renin�angiotensin system could modulate the oxidative stress metabolism, and also it seems that the manifestations of Angiotensin-(1-7) on the basal oxidative stress status are contradictory, with a variety of reports describing controversial (e.g. both pro-oxidant and antioxidant actions) effects for this heptapeptide. Our results presented here are confirming a possible antioxidant effect of Ang-(1�7) administration on rat, as shown by the increased levels of antioxidant enzymes from the temporal lobe (superoxide dismutase and glutathione peroxidase) and decreased levels of malondialdehyde, as an important lipid peroxidation parameter.

scholarly journals Functional expression of the renin-angiotensin system in human podocytes

2006 ◽  
Vol 290 (3) ◽  
pp. F710-F719 ◽  
Author(s):  
Max C. Liebau ◽  
D. Lang ◽  
J. Böhm ◽  
N. Endlich ◽  
Martin J. Bek ◽  
...  
Keyword(s):  
Renin Angiotensin System ◽  
Functional Expression ◽  
Kidney Cortex ◽  
Receptor Subtypes ◽  
Ang Ii ◽  
Angiotensin Receptor ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Beneficial Effects ◽  
Glomerular Proteinuria

Experimental and clinical studies impressively demonstrate that angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) significantly reduce proteinuria and retard progression of glomerular disease. The underlying intraglomerular mechanisms are not yet fully elucidated. As podocyte injury constitutes a critical step in the pathogenesis of glomerular proteinuria, beneficial effects of ACEI and ARB may partially result from interference with a local renin-angiotensin system (RAS) in podocytes. The knowledge of expression and function of a local RAS in podocytes is limited. In this study, we demonstrate functional expression of key components of the RAS in differentiated human podocytes: podocytes express mRNA for angiotensinogen, renin, ACE type 1, and the AT1 and AT2 angiotensin receptor subtypes. In Western blot experiments and immunostainings, expression of the AT1 and AT2 receptor was demonstrated both in differentiated human podocytes and in human kidney cortex. ANG II induced a concentration-dependent increase in cytosolic Ca2+ concentration via AT1 receptors in differentiated human podocytes, whereas it did not increase cAMP. Furthermore, ANG II secretion was detected, which was blocked by neither the ACEI captopril nor the renin inhibitor remikiren nor the chymase inhibitor chymostatin. ANG II secretion of podocytes was not increased by mechanical stress. Finally, ANG II was found to increase staurosporine-induced apoptosis in podocytes. We speculate that ACEI and ARB exert their beneficial effects, in part, by interfering with a local RAS in podocytes. Further experiments are required to identify the underlying molecular mechanism(s) of podocyte protection.

Abstract 227: The Protective Effect of Kidney-Specific ACE Inhibition Against Chronic Angiotensin II Infusions is Associated with Blunted Intrarenal Renin-Angiotensin System Activation

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Jorge F Giani ◽  
Tea Djandjoulia ◽  
Nicholas Fetcher ◽  
Sebastien Fuchs ◽  
Dale M Seth ◽  
...  
Keyword(s):  
Renin Angiotensin System ◽  
Fold Increase ◽  
Ace Inhibition ◽  
Sham Operation ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Intrarenal Ras ◽  
Failed Induction

Introduction: The responses to chronic angiotensin (Ang) II infusions of gene-targeted mice lacking kidney angiotensin-converting enzyme (ACE), in terms of intrarenal Ang II accumulation, hypertension, sodium and water retention are all blunted or absent. The objective of this study was to determine if these reduced responses were associated with changes in the intrarenal renin-angiotensin system (RAS). METHODS: Mice lacking intrarenal ACE (ACE10/10) were generated by targeted homologous recombination placing the expression of ACE only in macrophages. As a result, these mice have normal circulating ACE levels, but no kidney ACE. Wild-type (WT) mice of the same background (C57Bl/J) served as controls. Mice were subjected to sham-operation or subcutaneous infusion of Ang II for two weeks (n=6-10, 400 ng/kg/min via osmotic minipump). Mean arterial pressure (MAP) was followed by telemetry. At the end of the experiment, the kidneys were collected for analysis. Ang II content was measured by RIA. Renal abundance of ACE, angiotensinogen (AGT) and Ang II receptor type 1 (AT1R) were determined by Western Blot in total kidney homogenates. Results: At baseline, the MAP of WT and ACE 10/10 mice was similar 110 ± 4 mmHg vs. 109 ± 3 mmHg respectively (p>0.05). However, when subjected to chronic Ang II infusions, the hypertensive response was blunted in ACE 10/10 mice (129 ± 6 mmHg) vs. WT (146 ± 5 mmHg; P<0.05). Also, intrarenal Ang II accumulation was lower in ACE10/10 mice (724 ± 81 fmol/g) vs. WT (1130 ± 105 fmol/g, p<0.05). In non-treated mice, intrarenal RAS components analysis revealed that the absence of ACE in ACE10/10 mice was accompanied by a significant reduction in AGT (0.41 ± 0.06) and increased AT1R expression (1.32 ± 0.05) when compared to WT (normalized to 1.00, p<0.05 in both instances). Importantly, after chronic Ang II infusions, AGT, ACE and AT1R expression increased in WT (1.36, 1.26 and 1.17 fold increase respectively compared to non-treated WT, p<0.05) but not in the ACE10/10 mice (1.19, 1.06, 0.89 fold increase respectively compared to non-treated ACE10/10, p>0.05). Conclusion: The blunted hypertension and Ang II accumulation of mice devoid of kidney ACE in response to Ang II infusions is associated with a failed induction of renal AGT and the AT1R.

scholarly journals Activation of the Alternate Renin-Angiotensin System Correlates with the Clinical Status in Human Cirrhosis and Corrects Post Liver Transplantation

2019 ◽  
Vol 8 (4) ◽  
pp. 419 ◽  
Author(s):  
Stephen Casey ◽  
Robert Schierwagen ◽  
Kai Mak ◽  
Sabine Klein ◽  
Frank Uschner ◽  
...  
Keyword(s):  
Liver Transplantation ◽  
Liver Disease ◽  
Animal Studies ◽  
Clinical Status ◽  
Renin Angiotensin System ◽  
Blood Sampling ◽  
Ang Ii ◽  
Post Transplantation ◽  
Angiotensin System ◽  
Renin Angiotensin

Introduction: Recent animal studies have shown that the alternate renin-angiotensin system (RAS) consisting of angiotensin-converting enzyme 2 (ACE2), angiotensin-(1–7) (Ang-(1–7)) and the Mas receptor is upregulated in cirrhosis and contributes to splanchnic vasodilatation and portal hypertension. To determine the potential relevance of these findings to human liver disease, we evaluated its expression and relationship to the patients’ clinical status in subjects with cirrhosis. Methods: Blood sampling from peripheral and central vascular beds was performed intra-operatively for cirrhotic patients at the time of liver transplantation (LT) or trans-jugular intra-hepatic portosystemic shunt (TIPS) procedures to measure angiotensin II (Ang II) and Ang-(1–7) peptide levels and ACE and ACE2 enzyme activity. Relevant clinical and hemodynamic data were recorded pre-operatively for all subjects and peripheral blood sampling was repeated 3 months or later post-operatively. Results: Ang-(1–-7) and ACE2 activity were up-regulated more than twofold in cirrhotic subjects both at the time of LT and TIPS and levels returned to comparable levels as control subjects post-transplantation. Ang-(1–7) levels correlated positively with the degree of liver disease severity, as measured by the model for an end-stage liver disease (MELD) and also with clinical parameters of pathological vasodilatation including cardiac output (CO). There were strong correlations found between the ACE2:ACE and the Ang-(1–7):Ang II ratio highlighting the inter-dependence of the alternate and classical arms of the RAS and thus their potential impact on vascular tone. Conclusions: In human cirrhosis, the alternate RAS is markedly upregulated and the activation of this system is associated strongly with features of the hyperdynamic circulation in advanced human cirrhosis.

Abolition of long-term vascular influence of renin-angiotensin system

1990 ◽  
Vol 259 (2) ◽  
pp. H543-H553
Author(s):  
R. D. Randall ◽  
B. G. Zimmerman
Keyword(s):  
Blood Pressure ◽  
Vascular Tissue ◽  
Renin Angiotensin System ◽  
Ace Inhibition ◽  
Ang Ii ◽  
Flow Measurements ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Normal Controls

Rabbits were bilaterally nephrectomized for 24 h or received an angiotensin-converting enzyme (ACE) inhibitor chronically (5 days) before an acute experiment. Conductance responses to sympathetic nerve stimulation (SNS) (0.25, 0.75, and 2.25 Hz) and norepinephrine (NE) administration (0.2, 0.6, and 1.8 micrograms ia) were determined from simultaneous blood pressure and iliac blood flow measurements. Conductance responses to SNS were significantly reduced in nephrectomized (44, 26, and 20%) and chronic ACE inhibition (39, 31, and 24%) groups compared with normal controls, whereas conductance responses to NE were unchanged. Continuous infusion of angiotensin II (ANG II) for 24 h restored the depressed responses to SNS in nephrectomized and chronic ACE inhibition groups compared with normal controls but did not change conductance responses to NE. Acute ACE inhibition did not affect the conductance responses to SNS or NE compared with controls. Vascular tissue ACE activity was inhibited to a similar degree (50%) in both acute and chronic ACE inhibition groups compared with normal rabbits. Sodium depletion increased the conductance responses to SNS (30 and 24% at 0.25 and 0.75 Hz, respectively), but responses to NE were not affected. Chronic ACE inhibition significantly attenuated the conductance responses to SNS and slightly decreased responses to NE in sodium-depleted rabbits. Thus, in the anesthetized rabbit, the renin-angiotensin system potentiates the effect of SNS, presumably by ANG II acting at a prejunctional site, and this effect of ANG II appears to be long term in nature. Therefore, the renin-angiotensin system exerts a physiological role in the control of blood pressure in addition to the ability of this system to support arterial pressure in pathophysiological states.

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