Thermal dehydration-induced thirst in rats: role of angiotensin II

1991 ◽  
Vol 261 (5) ◽  
pp. R1171-R1175 ◽  
Author(s):  
C. C. Barney ◽  
J. S. Williams ◽  
D. H. Kuiper
Keyword(s):  
Angiotensin Ii ◽  
Water Intake ◽  
Water Deprivation ◽  
Physiological Responses ◽  
Heat Exposure ◽  
Plasma Renin ◽  
Thermal Dehydration ◽  
Converting Enzyme ◽  
Sprague Dawley

Dehydration can be brought about by either water deprivation or by heat exposure (thermal dehydration). Angiotensin II has been shown to have a role in water deprivation-induced thirst. The current study was designed to determine whether angiotensin II is involved in thirst caused by thermal dehydration. Male Sprague-Dawley strain rats were dehydrated by exposure to a 40 degree C environment for 2-4 h or by water deprivation for 44 h. Water deprivation but not heat exposure significantly increased plasma renin activity. Neither ureteric ligation nor nephrectomy significantly altered water intake after thermal dehydration. Captopril, an inhibitor of angiotensin converting enzyme, given at a dose of 100 mg/kg ip, significantly decreased water intake in water-deprived rats but not in thermally dehydrated rats. Angiotensin II therefore does not appear to play a role in the control of water intake of thermally dehydrated rats. The physiological responses to dehydration in rats are dependent on the way in which the dehydration is brought about.

Water deprivation-induced drinking in rats: role of angiotensin II

1983 ◽  
Vol 244 (2) ◽  
pp. R244-R248 ◽  
Author(s):  
C. C. Barney ◽  
R. M. Threatte ◽  
M. J. Fregly
Keyword(s):  
Angiotensin Ii ◽  
Plasma Renin Activity ◽  
Water Intake ◽  
Water Deprivation ◽  
Plasma Renin ◽  
Sodium Concentration ◽  
Renin Activity ◽  
Deprivation Period ◽  
Dependent Component

The role of angiotensin II in the control of water intake following deprivation of water for varying lengths of time was studied. Male rats were deprived of water for 0, 12, 24, 36, or 48 h. Water intakes were measured with and without pretreatment with the angiotensin I-converting enzyme inhibitor, captopril (50 mg/kg, ip). Captopril had no significant effect on water intake following either 0 or 12 h of water deprivation. However, captopril significantly attenuated water intake following 24-48 h of water deprivation with the magnitude of the attenuation increasing as the length of the period of water deprivation increased. Plasma renin activity was significantly increased over control levels after 24-48 h of water deprivation but not after 12 h of water deprivation. Plasma renin activity tended to increase as the length of the water-deprivation period increased. Serum osmolality and sodium concentration were significantly increased over control levels following 12-48 h of water deprivation. Serum osmolality and sodium concentration failed to show any further increases with increasing length of water deprivation beyond the increases following 12 h of water deprivation. The data indicate that the water intake of water-deprived rats can be divided into an angiotensin II-dependent component and angiotensin II-independent component. The angiotensin II-independent component appears to be more important in the early stages of water deprivation whereas the angiotensin II-dependent component becomes more important as the length of the water-deprivation period increases.

Role of arteria baroreceptor input on thirst and urinary responses to intracerebroventricular angiotensin II

1993 ◽  
Vol 265 (3) ◽  
pp. R591-R595 ◽  
Author(s):  
R. L. Thunhorst ◽  
S. J. Lewis ◽  
A. K. Johnson
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Arterial Blood Pressure ◽  
Water Intake ◽  
Enzyme Inhibitor ◽  
Ang Ii ◽  
Converting Enzyme ◽  
Arterial Blood ◽  
Endogenous Formation

Intracerebroventricular (icv) infusion of angiotensin II (ANG II) in rats elicits greater water intake under hypotensive, compared with normotensive, conditions. The present experiments used sinoaortic baroreceptor-denervated (SAD) rats and sham-operated rats to examine if the modulatory effects of arterial blood pressure on water intake in response to icv ANG II are mediated by arterial baroreceptors. Mean arterial blood pressure (MAP) was raised or lowered by intravenous (i.v.) infusions of phenylephrine (1 or 10 micrograms.kg-1 x min-1) or minoxidil (25 micrograms.kg-1 x min-1), respectively. The angiotensin-converting enzyme inhibitor captopril (0.33 mg/min) was infused i.v. to prevent the endogenous formation of ANG II during testing. Urinary excretion of water and solutes was measured throughout. Water intake elicited by icv ANG II was inversely related to changes in MAP. Specifically, rats drank more water in response to icv ANG II when MAP was reduced by minoxidil but drank less water when MAP was elevated by phenylephrine. The influence of changing MAP on the icv ANG II-induced drinking responses was not affected by SAD. These results suggest that the modulatory effects of arterial blood pressure on icv ANG II-induced drinking can occur in the absence of sinoaortic baroreceptor input.

Is angiotensin essential in drinking induced by water deprivation and caval ligation?

1981 ◽  
Vol 240 (1) ◽  
pp. R75-R80 ◽  
Author(s):  
M. C. Lee ◽  
T. N. Thrasher ◽  
D. J. Ramsay
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Water Intake ◽  
Water Deprivation ◽  
Essential Role ◽  
Vena Cava ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Renin Angiotensin

The role of the renin-angiotensin system in drinking induced by water deprivation and caval ligation was assessed by infusion of saralasin into the lateral ventricles of rats. This technique was first validated by demonstrating its capability to specifically antagonize drinking to both systemic and central angiotensin II. However, neither the latency to drink nor the amount of water consumed following 24- or 30-h water deprivation was affected by saralasin. Furthermore, saralasin had no significant effect on the recovery of blood pressure or on the water intake following ligation of the abdominal vena cava. These observations suggest that the renin-angiotensin system alone does not play an essential role in the control of drinking following water deprivation or caval ligation in rats.

Thermal dehydration-induced thirst in rats: role of body temperature

1995 ◽  
Vol 269 (3) ◽  
pp. R557-R564 ◽  
Author(s):  
C. C. Barney ◽  
M. M. Folkerts
Keyword(s):  
Body Temperature ◽  
Core Temperature ◽  
Water Intake ◽  
Thermal Dehydration ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Access To Water

Male Sprague-Dawley rats were used to study the possible role of hyperthermia in the thirst associated with thermal dehydration. Rats were exposed to 40 degrees C for 4 h and then allowed access to water at different times after they were transferred to 25 degrees C. Delaying the time prior to allowing the rats to drink did not significantly alter either water intake or percent rehydration even though core temperature decreased during the first 1.5 h after removal from the heat. Exposing thermally dehydrated rats to 5 degrees C for 30 min prior to allowing them access to water also failed to significantly affect water intake or percent rehydration. Thermally dehydrated rats allowed to drink while remaining in the heat did not show a significant increase in water intake during the first hour or percent rehydration over rats drinking at 25 degrees C. Nondehydrated rats did show significant increases in water intake and percent rehydration when allowed to drink in the heat. Hyperthermia does not play a role in drinking in thermally dehydrated rats but can stimulate drinking in water-replete rats.

Effect of enalapril (MK-421), an orally active angiotensin I converting enzyme inhibitor, on blood pressure, active and inactive plasma renin, urinary prostaglandin E2, and kallikrein excretion in conscious rats

1984 ◽  
Vol 62 (1) ◽  
pp. 116-123 ◽  
Author(s):  
Ernesto L. Schiffrin ◽  
Jolanta Gutkowska ◽  
Gaétan Thibault ◽  
Jacques Genest
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Ace Inhibition ◽  
Renin Activity ◽  
Prostaglandin E ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Angiotensin I Converting Enzyme

The angiotensin I converting enzyme (ACE) inhibitor enalapril (MK-421), at a dose of 1 mg/kg or more by gavage twice daily, effectively inhibited the pressor response to angiotensin I for more than 12 h and less than 24 h. Plasma renin activity (PRA) did not change after 2 or 4 days of treatment at 1 mg/kg twice daily despite effective ACE inhibition, whereas it rose significantly at 10 mg/kg twice daily. Blood pressure fell significantly and heart rate increased in rats treated with 10 mg/kg of enalapril twice daily, a response which was abolished by concomitant angiotensin II infusion. However, infusion of angiotensin II did not prevent the rise in plasma renin. Enalapril treatment did not change urinary immunorcactive prostaglandin E2 (PGE2) excretion and indomethacin did not modify plasma renin activity of enalapril-treated rats. Propranolol significantly reduced the rise in plasma renin in rats receiving enalapril. None of these findings could be explained by changes in the ratio of active and inactive renin. Water diuresis, without natriuresis and with a decrease in potassium urinary excretion, occurred with the higher dose of enalapril. Enalapril did not potentiate the elevation of PRA in two-kidney one-clip Goldblatt hypertensive rats. In conclusion, enalapril produced renin secretion, which was in part β-adrenergically mediated. The negative short feedback loop of angiotensin II and prostaglandins did not appear to be involved. A vasodilator effect, apparently independent of ACE inhibition, was found in intact conscious sodium-replete rats.

Renal hemodynamic responses to increased renal venous pressure: role of angiotensin II

1982 ◽  
Vol 243 (3) ◽  
pp. F260-F264 ◽  
Author(s):  
P. R. Kastner ◽  
J. E. Hall ◽  
A. C. Guyton
Keyword(s):  
Angiotensin Ii ◽  
Filtration Rate ◽  
Enzyme Inhibitor ◽  
Venous Pressure ◽  
Renin Secretion ◽  
Ang Ii ◽  
Converting Enzyme ◽  
Filtration Fraction ◽  
A Value

Studies were performed to quantitate the effects of progressive increases in renal venous pressure (RVP) on renin secretion (RS) and renal hemodynamics. RVP was raised in 10 mmHg increments to 50 mmHg. Renin secretion rate increased modestly as RVP was increased to 30 mmHg and then increased sharply after RVP exceeded 30 mmHg. Glomerular filtration rate (GFR), renal blood flow (RBF), and filtration fraction (FF) did not change significantly when RVP was elevated to 50 mmHg. GFR and RBF were also measured after the renin-angiotension system (RAS) was blocked with the angiotensin converting enzyme inhibitor (CEI) SQ 14225. After a 60-min CEI infusion, RBF was elevated (32%), GFR was unchanged, FF was decreased, and total renal resistance (TRR) was decreased. As RVP was increased to 50 mmHg, GFR and FF decreased to 36.3 and 40.0% of control, respectively, RBF returned to a value not significantly different from control, and TRR decreased to 44.8% of control. The data indicate that the RAS plays an important role in preventing reductions in GFR during increased RVP because blockade of angiotensin II (ANG II) formation by the CEI results in marked decreases in GFR at high RVPs. The decreases in GFR after ANG II blockade and RVP elevation were not due to lack of renal vasodilation, since TRR was maintained below while RBF was maintained either above or at the pre-CEI levels.

P0527HYPERGLYCEMIA-ASSOCIATED ACUTE KIDNEY INJURY INCREASES THE SUSCEPTIBILITY TOWARDS NEUROLOGICAL DYSFUNCTION: ROLE OF ANGIOTENSIN II TYPE 2 RECEPTOR AND ANGIOTENSIN-CONVERTING ENZYME 2

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Nisha Sharma ◽  
Anil Bhanudas Gaikwad
Keyword(s):  
Angiotensin Ii ◽  
Combination Therapy ◽  
Angiotensin Converting Enzyme ◽  
Neurological Dysfunction ◽  
Histopathological Analysis ◽  
Mrna Levels ◽  
Converting Enzyme ◽  
Angiotensin Converting Enzyme 2

Abstract Background and Aims In clinical settings, diabetics remain on higher risk of ischemic renal injury (IRI) than nondiabetic patients. In addition, IRI predisposes distant organs to dysfunction such as neurological impairments via activation of the pressor arm of renin-angiotensin system (RAS). In contrast, the role of depressor arm of RAS on IRI-associated neurological sequalae remains elusive. Hence, this study explored the role of angiotensin II type 2 receptor (AT2R) and angiotensin-converting enzyme 2 (ACE2) in IRI-associated neurological dysfunctions under nondiabetic (ND) and diabetes mellitus (DM) condition. Method Type 1 diabetes was induced by injecting streptozotocin (55 mg/kg i.p.). ND and DM rats with bilateral IRI were treated with AT2R agonist-Compound 21 (C21) (0.3 mg/kg/day, i.p.) or ACE2 activator-Diminazene Aceturate (Dize), (5 mg/kg/day, p.o.) per se or in combination therapy. Behavioural, biochemical, and histopathological analysis were done to assess IRI-induced neurological impairment. Moreover, immunohistochemistry, ELISA and qRT-PCR experiments were conducted for molecular mechanism analysis. Result In ND and DM rats, IRI caused hippocampal complications as evidenced by increased MDA and nitrite levels, augmented inflammatory cytokines (granulocyte colony stimulating factor, glial fibrillary acidic protein), altered protein and mRNA expressions of Ang II, Ang-(1-7), AT1R, AT2R and MasR. In contrast, concomitant therapy of C21 and Dize effectively normalised aforementioned hippocampal alterations. The protective effect of combination therapy was exerted due to augmented protein and mRNA levels of depressor arm components. Conclusion The current study demonstrated the protective role of AT2R agonist and ACE2 activator in IRI-associated neurological dysfunction through preventing oxidative stress, inflammation and upregulating brain depressor arm of RAS under ND and DM conditions.

Thirst and brain angiotensin in cattle

1992 ◽  
Vol 262 (2) ◽  
pp. R204-R210
Author(s):  
J. R. Blair-West ◽  
D. A. Denton ◽  
M. J. McKinley ◽  
R. S. Weisinger
Keyword(s):  
Angiotensin Ii ◽  
Water Intake ◽  
Enzyme Inhibitors ◽  
Converting Enzyme ◽  
Preoptic Nucleus ◽  
Angiotensin I ◽  
Converting Enzyme Inhibitors ◽  
Median Preoptic Nucleus ◽  
Angiotensin I Converting Enzyme ◽  
Reduced Water

Cows that were normally hydrated or deprived of water were given intravenous or intracerebroventricular (icv) infusions of angiotensin I converting-enzyme inhibitors (CEI) or angiotensin II antagonists. Normally hydrated Na-deficient cows increased water intake in a dose-related manner in response to icv infusion of angiotensin I (n = 5). The response to 3 micrograms/h angiotensin I was abolished by concurrent icv infusion of the CEI captopril at 3 mg/h but not by intravenous infusion of captopril at 120 mg/h, which reduced Na appetite (n = 5). The icv infusion of captopril at 12 mg/h did not reduce the water intake of cows that were water restricted for 26.5 h (n = 4) or water restricted and Na deficient (n = 4). The icv infusion of the more lipophilic CEI ramipril at 3 mg/h (n = 7) did not reduce the water intake of normally hydrated or dehydrated cows but reduced the "need-free" intake of Na solution by dehydrated cows. The icv infusion of the nonpeptide antagonist Du Pont 753 at 3 mg/h (n = 7) reduced water intake in dehydrated cows. The results indicate that brain angiotensin may be involved in thirst in cattle. The data suggest that this brain angiotensin II may be formed by a pathway that does not include converting enzyme and that is sited inside the blood brain barrier, possibly in the median preoptic nucleus.

Role of vasopressin in blood pressure regulation in conscious water-deprived dogs

1983 ◽  
Vol 244 (1) ◽  
pp. R74-R77 ◽  
Author(s):  
J. Schwartz ◽  
I. A. Reid
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Plasma Renin Activity ◽  
Water Deprivation ◽  
Plasma Renin ◽  
Renin Activity ◽  
Pressure Regulation

The role of vasopressin in the regulation of blood pressure during water deprivation was assessed in conscious dogs with two antagonists of the vasoconstrictor activity of vasopressin. In water-replete dogs, vasopressin blockade caused no significant changes in mean arterial pressure, heart rate, plasma renin activity (PRA), or plasma corticosteroid concentration. In the same dogs following 48-h water deprivation, vasopressin blockade increased heart rate from 85 +/- 6 to 134 +/- 15 beats/min (P less than 0.0001), increased cardiac output from 2.0 +/- 0.1 to 3.1 +/- 0.1 1/min (P less than 0.005), and decreased total peripheral resistance from 46.6 +/- 3.1 to 26.9 +/- 3.1 U (P less than 0.001). Plasma renin activity increased from 12.4 +/- 2.2 to 25.9 +/- 3.4 ng ANG I X ml-1 X 3 h-1 (P less than 0.0001) and plasma corticosteroid concentration increased from 3.2 +/- 0.7 to 4.9 +/- 1.2 micrograms/dl (P less than 0.05). Mean arterial pressure did not change significantly. When the same dogs were again deprived of water and pretreated with the beta-adrenoceptor antagonist propranolol, the heart rate and PRA responses to the antagonists were attenuated and mean arterial pressure decreased from 103 +/- 2 to 91 +/- 3 mmHg (P less than 0.001). These data demonstrate that vasopressin plays an important role in blood pressure regulation during water deprivation in conscious dogs.

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