scholarly journals Renal adaptation during hibernation

2013 ◽  
Vol 305 (11) ◽  
pp. F1521-F1532 ◽  
Author(s):  
Alkesh Jani ◽  
Sandra L. Martin ◽  
Swati Jain ◽  
Daniel Keys ◽  
Charles L. Edelstein
Keyword(s):  
Core Body Temperature ◽  
Renal Plasma Flow ◽  
Renin Angiotensin System ◽  
Organ Injury ◽  
Extreme Conditions ◽  
Physiological Changes ◽  
Protective Mechanisms ◽  
Angiotensin System ◽  
Renal Adaptation ◽  
Core Body

Hibernators periodically undergo profound physiological changes including dramatic reductions in metabolic, heart, and respiratory rates and core body temperature. This review discusses the effect of hypoperfusion and hypothermia observed during hibernation on glomerular filtration and renal plasma flow, as well as specific adaptations in renal architecture, vasculature, the renin-angiotensin system, and upregulation of possible protective mechanisms during the extreme conditions endured by hibernating mammals. Understanding the mechanisms of protection against organ injury during hibernation may provide insights into potential therapies for organ injury during cold storage and reimplantation during transplantation.

Role of the renin-angiotensin system in mediating the effects of posture on renal function

1996 ◽  
Vol 271 (1) ◽  
pp. R282-R288 ◽  
Author(s):  
G. A. Reinhart ◽  
T. E. Lohmeier
Keyword(s):  
Renal Function ◽  
Sodium Excretion ◽  
Renal Plasma Flow ◽  
Renin Angiotensin System ◽  
Renal Hemodynamics ◽  
Conscious Dogs ◽  
Plasma Norepinephrine ◽  
Ang Ii ◽  
Angiotensin System ◽  
Renin Angiotensin

This study was designed to quantitate the influence of the neurohumoral activation associated with orthostatic stress on renal hemodynamics and sodium excretion and, furthermore, to determine the importance of the renin-angiotensin system in mediating these changes in renal function. Seven conscious dogs were studied while lying in the recumbent position and, subsequently, after standing in a supporting sling. Experiments were conducted under control conditions and after plasma angiotensin II (ANG II) concentration was fixed at control levels by chronic infusion of captopril (14 micrograms.kg-1.min-1) and ANG II (0.5 +/- 0.02 ng.kg-1.min-1). During control experiments, 45 min of standing increased plasma renin activity twofold, whereas mean arterial pressure, heart rate, and plasma norepinephrine concentration remained unchanged. During standing, glomerular filtration rate (GFR) and renal plasma flow (RPF) fell to 88 +/- 2 and 77 +/- 3% of recumbent values, respectively, whereas filtration fraction (FF) increased 16 +/- 1%. Additionally, urinary (UNaV) and fractional sodium excretion (FENa) decreased to 27 +/- 6 and 30 +/- 7% of recumbent values, respectively. When plasma ANG II concentration was fixed at control levels during standing, there were no significant changes in GFR, whereas increments in FF and reductions in RPF, UNaV, and FENa were attenuated by 63, 40, 30, and 33%, respectively. These data suggest that, in conscious dogs, standing in a supporting sling causes reflex activation of the sympathetic nervous and renin-angiotensin systems, eliciting reductions in GFR, RPF, and UNaV. Furthermore, ANG II contributes significantly to the effects of passive standing on renal hemodynamics and UNaV.

Renin-angiotensin system modulates renal bradykinin production

1996 ◽  
Vol 271 (4) ◽  
pp. R1090-R1095 ◽  
Author(s):  
H. M. Siragy ◽  
A. A. Jaffa ◽  
H. S. Margolius ◽  
R. M. Carey
Keyword(s):  
Renal Plasma Flow ◽  
Renin Angiotensin System ◽  
At1 Receptor ◽  
Sodium Depletion ◽  
Kinin System ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Renal Kallikrein ◽  
Kallikrein Kinin System ◽  
Cgmp Formation

Previous studies have shown that sodium depletion is associated with an increase in renal kallikrein-kinin system activity. This system may play an important role in counterbalancing the renal effects of the renin-angiotensin system. In this study, we examined whether the renal renin-angiotensin system participates in the regulation of renal bradykinin (BK) levels during sodium depletion. We measured changes in renal excretory and hemodynamic function, renal interstitial fluid (RIF) BK, and RIF and urinary guanosine 3',5'-cyclic monophosphate (cGMP) and prostaglandin E2 (PGE2) in conscious uninephrectomized dogs (n = 5) in sodium metabolic balance (10 meq/day) in response to intrarenal arterial administration of the renin inhibitor ACRIP (0.2 microgram.kg-1.min-1) or angiotensin II AT1-receptor blocker losartan (100 ng.kg-1.min-1). ACRIP and losartan increased urine flow rate from 0.75 +/- 0.06 to 1.6 +/- 0.03 and 1.5 +/- 0.05 ml/min, respectively (each P < 0.001), and urine sodium excretion from 5.4 +/- 0.7 to 18.3 +/- 1.3 and 15.9 +/- 1.2 meq/min, respectively (each P < 0.001). Glomerular filtration rate and renal plasma flow increased only during losartan administration (P < 0.05). ACRIP decreased RIF BK by 48%, from 33.1 +/- 3.8 to 17.4 +/- 4.1 pg/min (P < 0.01). ACRIP decreased RIF cGMP by 38%, from 0.69 +/- 0.08 to 0.43 +/- 0.1 pmol/min (P < 0.01); urinary cGMP by 16%, from 0.63 +/- 0.05 to 0.53 +/- 0.02 pmol/min (P < 0.05); and RIF PGE2 by 46%, from 10.5 +/- 1.1 to 5.7 +/- 1.1 pg/min (P < 0.01). Urinary PGE2 was unchanged by ACRIP. Losartan decreased RIF PGE2 by 71%, from 10.8 +/- 0.6 to 3.1 +/- 0.6 pg/min (P < 0.01) but failed to change RIF BK, RIF cGMP, urinary cGMP, or urinary PGE2. These data suggest that the renin-angiotensin system tonically stimulates renal BK production and cGMP formation via a non-AT1 angiotensin receptor and renal PGE2 production via the AT1 receptor.

Activity and responsiveness of the renin-angiotensin system in the aging rat

2000 ◽  
Vol 279 (5) ◽  
pp. R1787-R1794 ◽  
Author(s):  
Michele M. Thompson ◽  
Terry T. Oyama ◽  
Francis J. Kelly ◽  
Thomas M. Kennefick ◽  
Sharon Anderson
Keyword(s):  
Plasma Flow ◽  
Renal Plasma Flow ◽  
Renin Angiotensin System ◽  
Angiotensin Converting Enzyme Inhibitors ◽  
Sprague Dawley ◽  
Converting Enzyme Inhibitors ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Age Related ◽  
Early Aging

The systemic renin-angiotensin system (RAS) is suppressed in normal aging, but the activity of the tissue RAS is not well defined. We examined the systemic and intrarenal RAS status of aging normal rats and responses to suppression and stimulation of the production of endogenous ANG II. Studies were performed in young (3 mo) and early aging (15 mo) male Sprague-Dawley rats. Angiotensin-converting enzyme inhibitors modestly decreased mean arterial pressure (MAP) in young (3 mo) and early aging (15 mo) rats and limited proteinuria in the older rats. There were no significant age-related effects on renal function or on endogenous RAS activity. Intravenous infusion of the precursor ANG I led to comparable increases in MAP in younger and older rats. In contrast, the renal effects (reduction in glomerular filtration and plasma flow rates) were exaggerated in the older animals. Intrarenal arterial ANG I did not affect MAP in any group. In young rats, there were no significant hemodynamic effects in either the ipsilateral (infused) or the contralateral (noninfused) kidney. In the older rats, both kidneys had a significant fall in renal renal plasma flow rate (RPF) with left renal arterial infusion of ANG I. Accordingly, these studies early in the course of aging found only subtle changes in the activity, responsiveness, and metabolism of the RAS. Thus early aging is associated with a modest but important increase in sensitivity to RAS stimulation.

scholarly journals 182: RENIN-ANGIOTENSIN SYSTEM MARKERS AND NONPULMONARY ORGAN INJURY IN SEVERE COVID-19 PNEUMONIA

2021 ◽  
Vol 50 (1) ◽  
pp. 75-75
Author(s):  
Daniel Leisman ◽  
Arnav Mehta ◽  
Nir Hacohen ◽  
Michael Filbin ◽  
Marcia Goldberg
Keyword(s):  
Renin Angiotensin System ◽  
Organ Injury ◽  
Angiotensin System ◽  
Renin Angiotensin

Effect of losartan and enalapril on renal adaptation sodium restriction in rat

1994 ◽  
Vol 267 (2) ◽  
pp. F281-F288 ◽  
Author(s):  
B. Jover ◽  
D. Saladini ◽  
N. Nafrialdi ◽  
M. Dupont ◽  
A. Mimran
Keyword(s):  
Sodium Excretion ◽  
Combined Treatment ◽  
Renin Angiotensin System ◽  
Systolic Arterial Pressure ◽  
Dietary Sodium ◽  
High Dose ◽  
Angiotensin System ◽  
Low Sodium ◽  
Renal Adaptation ◽  
Microsphere Method

The influence of losartan (10 or 30 mg.kg-1.day-1), enalapril (10 mg.kg-1.day-1), and combined treatment by losartan and enalapril on the renal adaptation to dietary sodium withdrawal was assessed in normal rats. Treatments were given by gavage for 3 days before and during the 6-day period of low-sodium (LS) diet. Cumulative sodium excretion during LS was similar in untreated and low-dose losartan groups (0.62 +/- 0.07 and 0.75 +/- 0.07 mmol/6 days), whereas it was significantly increased in groups treated by the high dose of losartan and enalapril alone or combined with both doses of losartan (1.38 +/- 0.16, 1.50 +/- 0.10, 1.37 +/- 0.16, and 1.12 +/- 0.03 mmol/6 days, respectively). A decrease in conscious systolic arterial pressure was observed in all treated groups in response to LS. At the end of LS, conscious renal blood flow (microsphere method) was similarly increased in all treated groups. Creatinine clearance decreased to a similar extent with both doses of losartan, whereas a further reduction was observed with enalapril given alone or combined with losartan. These results demonstrate that the enalapril-induced disturbance in the response of renal sodium excretion to LS is mainly related to angiotensin-mediated mechanisms. However, non-angiotensin-related actions of enalapril may contribute to the deterioration of renal function in sodium-restricted animals. In addition, a high dose of losartan is required to impair renal sodium conservation, thus suggesting that the tubular renin-angiotensin system may play a crucial role in the renal adaptation to dietary sodium withdrawal.

scholarly journals Renin Angiotensin System in Cognitive Function and Dementia

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Vijaya Lakshmi Bodiga ◽  
Sreedhar Bodiga
Keyword(s):  
Cognitive Function ◽  
Renin Angiotensin System ◽  
Organ Injury ◽  
Ang Ii ◽  
Microvascular Damage ◽  
Angiotensin System ◽  
Cerebrovascular Pathology ◽  
Beneficial Effects ◽  
Mas Receptor ◽  
End Stage

Angiotensin II represents a key molecule in hypertension and cerebrovascular pathology. By promoting inflammation and oxidative stress, enhanced Ang II levels accelerate the onset and progression of cell senescence. Sustained activation of RAS promotes end-stage organ injury associated with aging and results in cognitive impairment and dementia. The discovery of the angiotensin-converting enzyme ACE2-angiotensin (1–7)-Mas receptor axis that exerts vasodilator, antiproliferative, and antifibrotic actions opposed to those of the ACE-Ang II-AT1 receptor axis has led to the hypothesis that a decrease in the expression or activity of angiotensin (1–7) renders the systems more susceptible to the pathological actions of Ang II. Given the successful demonstration of beneficial effects of increased expression of ACE2/formation of Ang1–7/Mas receptor binding and modulation of Mas expression in animal models in containing cerebrovascular pathology in hypertensive conditions and aging, one could reasonably hope for analogous effects regarding the prevention of cognitive decline by protecting against hypertension and cerebral microvascular damage. Upregulation of ACE2 and increased balance of Ang 1–7/Ang II, along with positive modulation of Ang II signaling through AT2 receptors and Ang 1–7 signaling through Mas receptors, may be an appropriate strategy for improving cognitive function and treating dementia.

scholarly journals Hemodynamic and biological correlates of glomerular hyperfiltration in sickle cell patients before and under renin–angiotensin system blocker

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jean-Philippe Haymann ◽  
Nadjib Hammoudi ◽  
Marine Livrozet ◽  
Aline Santin ◽  
Sarah Mattioni ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Sickle Cell ◽  
Reticulocyte Count ◽  
Enzyme Inhibitor ◽  
Renal Plasma Flow ◽  
Renin Angiotensin System ◽  
Glomerular Hyperfiltration ◽  
Angiotensin System ◽  
Key Factor ◽  
Chronic Hemolysis

AbstractGlomerular hyperfiltration alone or associated with albuminuria is a well-known feature of sickle cell associated nephropathy. Though, glomerular hyperfiltration is currently considered to be related to a high renal plasma flow and chronic hemolysis, cardiac output influence on measured glomerular filtration rate (mGFR) have not been investigated so far. Thirty seven homozygous sickle cell patients (SCA) from the RAND study investigated before and under angiotensin converting enzyme inhibitor (ACEI) were included. Both mGFR and cardiac index (CI) were high (> 110 ml/min/1.73 m2 and > 3.5 l/m2 in 81% and 97% of cases) with low systemic vascular resistance (SVR) (< 700 dynes/s/cm−5) in 38% of cases. mGFR association with CI and SVR were significant at baseline (respectively ρ: 0.44, p = 0.008 and ρ: − 0.37, p = 0.02) and under ACEI (p = 0.007 and 0.01 respectively), in accordance with previous data showing that hyperfiltration was linked to an increased glomerular perfusion and a glomerulomegaly rather than increased capillary hydrostatic pressure. Of notice, after adjustment on CI, mGFR remained associated with reticulocyte count and albuminuria under ACEI (p = 0.006 and 0.02 respectively). Our results suggest that hyperfiltration is tightly linked to an increased cardiac output which may account for an increased renal blood flow. Chronic hemolysis could be a relevant factor accounting for hyperfiltration potentially acting on glomerular enlargement which appears as a key factor. Our data suggest that cardiac output assessment is a relevant tool in the routine management and monitoring of SCA nephropathy.

scholarly journals A randomized intervention study to evaluate the effect of calcitriol therapy on the renin-angiotensin system in diabetes

2018 ◽  
Vol 19 (1) ◽  
pp. 147032031775417 ◽  
Author(s):  
Sarah Zaheer ◽  
Kiara Taquechel ◽  
Jenifer M Brown ◽  
Gail K Adler ◽  
Jonathan S Williams ◽  
...  
Keyword(s):  
Vitamin D ◽  
Angiotensin Ii ◽  
Disease Risk ◽  
Renal Plasma Flow ◽  
Cardiovascular Disease Risk ◽  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Controlled Study ◽  
Angiotensin System ◽  
Renin Angiotensin

Background: Prior studies suggest that vitamin D therapy may decrease cardiovascular disease risk in type 2 diabetes (T2DM) by lowering renin-angiotensin system (RAS) activity. However, randomized human intervention studies to evaluate the effect of vitamin D receptor (VDR) agonists on RAS activity are lacking. Objective: The objective of this article is to investigate the effect of direct VDR activation with calcitriol on circulating RAS activity and vascular hemodynamics in T2DM. Methods: A randomized, double-blinded, and placebo-controlled study wherein 18 participants with well-controlled T2DM without chronic kidney disease (CKD) were administered calcitriol or placebo for three weeks was conducted. Outcome measures included plasma renin activity (PRA), serum and urinary aldosterone, mean arterial pressure (MAP) before and after an infusion of angiotensin II, and renal plasma flow (RPF) via para-aminohippurate clearance. Results: Despite an increase in 1,25(OH)2D with calcitriol administration (45.4 to 61.8 pg/ml, p = 0.03) and no change with placebo, there were no significant differences in PRA, serum or urinary aldosterone, baseline and angiotensin II-stimulated MAP, or basal and angiotensin II-stimulated RPF between interventions. Conclusion: In this randomized and placebo-controlled study in participants with T2DM without CKD, calcitriol therapy to raise 1,25(OH)2D levels, when compared with placebo, did not significantly change circulating RAS activity or vascular hemodynamics.

scholarly journals Heat Exposure and Physiological Changes among Cooks

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Siti Marwanis Anua ◽  
Mohd Nizamuddin Ismail ◽  
Mohd Amierul Aieman Mohd Nordin ◽  
Faridah Naim ◽  
Nurul Ainun Hamzah ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Body Temperature ◽  
Core Body Temperature ◽  
Sampling Site ◽  
Heat Exposure ◽  
Physiological Changes ◽  
Sweat Production ◽  
Core Body ◽  
Post Shift

Cooks who are exposed to heat produced from stoves when working in the kitchen are at risk of thermal stress and heat-related illness. Physiological changes such as increased heart rate, sweat production and blood pressure may also affect them. This study aimed to determine the area heat exposure levels and physiological changes including core body temperature, blood pressure and heart rate during pre-, mid- and post-shift among cooks and its association, and to compare the mean difference of physiological changes between the shifts. This cross-sectional study utilised the purposive sampling method and recruited 30 cooks from food stalls and cafeterias in Kelantan. Area heat measurements were collected from 14 sites (7 inside and 7 outside the USM Health Campus). Wet-bulb Globe Temperature (WBGT) monitor was mounted on a tripod at 1.1 m height near the source of heat for 8 hours. The core body temperature, blood pressure, and heart rate were taken three times per day during pre-, mid- and post-shift for physiological changes measurement. Respondents’ personal information, health history, work description, and symptoms of heat-related illness were collected using a questionnaire. The overall WBGT area levels at each sampling site were homogeneously distributed. There was significant increase in core body temperature and heart rate from pre-shift to post-shift. However, there was no significant correlation (p>0.05) between heat exposure (WBGT index) established with the physiological changes. This may suggest that the increase in core body temperature and heart rate might be attributed to other factors and needed further investigation.

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