Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of captopril and of other angiotensin-converting enzyme inhibitors (zofenopril, fosenopril and enalaprilic acid) were tested on the isolated rabbit heart and aorta. Captopril elicited an erratic negative inotropic effect and a reduction in basal coronary perfusion pressure (10(-5)-10(-4) M). The increase of coronary perfusion pressure induced by vasopressin, methoxamine, angiotensin II and Bay K 8644 was partially antagonized by captopril (10(-7)-10(-4) M) in a non-specific manner. These actions were not modified by saralasin or indomethacin and by ex vivo pretreatment with captopril itself. On the aortic strips, the contraction plateau induced by KCl and angiotensin II was partially inhibited (10(-6)-10(-4) M), while no effect was observed on those induced by noradrenaline, serotonin and PGF2 alpha. The Ca2+ concentration-response curve appeared shifted to the right in a non-competitive manner. The other angiotensin-converting enzyme inhibitors showed no effect up to 10(-4) M on isolated heart or aorta. Results obtained with captopril were consistent with vasorelaxant activity independent of the tissue renin-angiotensin system. Modulatory activity on the intracellular calcium movement may be involved.
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PMID:Different effects of captopril and other angiotensin converting enzyme inhibitors on cardiovascular preparations. 174 46

The effects of lifetime captopril treatment on vasopressin (VP) were assessed in spontaneously hypertensive rats (SHR). Pregnant and nursing dams were treated with oral Captopril (100 mg/kg/day). After weaning, the pups were maintained on Captopril (50/kg/day) for 19-20 wks. Blood pressures of Captopril-treated SHR were in the normotensive range and significantly lower (p less than .001) than SHR control rats. Control and Captopril-treated SHR were perfused and brains were sectioned for immunohistochemical staining with a polyclonal antibody directed against vasopressin (VP). Compared to control SHR, Captopril-treated rats displayed decreased VP-like immunoreactivity in the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus. Captopril treatment also selectively decreased the number of brightly labeled cell bodies in the SON and PVN and reduced VP-like labeling in the axons of the neurons in these nuclei. Concurrent with a decrease in VP-like immunoreactivity, Captopril treatment reduced plasma VP levels (RIA) (p less than 0.01, Captopril, 5.6 +/- 0.5 pg/ml; control, 11.8 +/- 2.2 pg/ml). Scatchard analysis of 3H-VP binding indicated that Captopril treatment increased the number but not the affinity of VP receptors in the hypothalamus and brain stem of SHR. These results suggest that in SHR oral Captopril treatment attenuates the synthesis and release of VP, an effect that may contribute to the blood pressure lowering effect of converting enzyme inhibitors.
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PMID:Alterations in vasopressin mechanisms in captopril-treated spontaneously hypertensive rats. 177 93

In order to investigate the physiological role of angiotensin II (ANG II) in the control of vasopressin (VP) secretion, the VP responses to hypotension induced by hemorrhage (20 ml/kg, n = 10) or nitroprusside infusion (1-10 micrograms/kg.min, n = 9) were studied with or without blockade of ANG II formation by the converting enzyme inhibitor captopril in conscious rabbits. Administration of captopril (5 mg/kg, iv) caused a small decrease in mean arterial pressure but did not enhance the hypotensive response to subsequent hemorrhage or nitroprusside infusion. The renin response to both stimuli was enhanced by captopril, whereas the increase in plasma ANG II concentration was attenuated. Plasma VP (PAVP) concentration increased during hemorrhage (2.0 +/- 0.2-113.6 +/- 47.7 pg/ml, P less than 0.01) and nitroprusside infusion (2.1 +/- 0.3-5.1 +/- 1.0 pg/ml, P less than 0.01). Captopril did not change basal plasma PAVP, nor did it attenuate the VP responses to hemorrhage or nitroprusside. Indeed, captopril tended to enhance the VP responses to hemorrhage (2.3 +/- 0.3-147.1 +/- 65.9 pg/ml) and nitroprusside infusion (1.9 +/- 0.2-15.4 +/- 6.0 pg/ml). The relationship between log PAVP and mean arterial pressure during hemorrhage and nitroprusside infusion in the presence of captopril was not different than in the absence of captopril. These results indicate that in conscious rabbits, the renin-angiotensin system does not contribute to the increase in VP secretion during hypotension induced by hemorrhage or nitroprusside infusion.
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PMID:Role of endogenous angiotensin II in the control of vasopressin secretion during hypovolemia and hypotension in conscious rabbits. 198 18

This study examined whether angiotensin II (ANG II) influences the pressure-natriuretic (PN) response by altering renal cortical or medullary hemodynamics. Studies were performed in Inactin-anesthetized rats that were acutely volume expanded to maintain plasma renin activity and ANG II levels in the physiological range. Neural influences on the kidney were eliminated by renal denervation, and plasma levels of norepinephrine, vasopressin, cortisol, and aldosterone were fixed by intravenous infusion. In control rats (n = 8), sodium excretion increased from 3 to 17 microeq.min-1.g kidney wt-1 as renal perfusion pressure (RPP) was elevated from 96 to 141 mmHg (n = 8). Captopril (2 mg/kg, n = 9) reduced plasma levels of ANG II from 48 +/- 5 to 18 +/- 2 pg/ml, but it did not alter the PN relationship. Infusion of ANG II (20 ng.kg-1.min-1, n = 9) increased plasma levels of ANG II to 232 +/- 42 pg/ml and shifted the PN relationship to the right by 14 mmHg. Captopril increased renal blood flow, and infusion of ANG II returned it to control. Captopril had no effect on glomerular filtration rate (GFR) or glomerular capillary pressure (Pglom); however, subsequent ANG II infusion decreased Pglom from 56 +/- 2 to 48 +/- 2 mmHg and reduced GFR by 30%. Neither captopril nor ANG II altered papillary bloodflow or vasa recta capillary pressure at normal levels of RPP. These results indicate that the shift of the PN relationship during infusion of ANG II is due to a decrease in filtered load and enhanced tubular reabsorption of sodium. Acute blockade of the renin-angiotensin system had little effect on the PN response in volume-expanded rats despite affecting renal hemodynamics, because either the plasma and/or intrarenal levels of ANG II were already suppressed below those needed to influence tubular function or volume expansion inhibits tubular reabsorption in the nephron segments normally influenced by ANG II.
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PMID:Influence of angiotensin II on pressure natriuresis and renal hemodynamics in volume-expanded rats. 205 47

The diabetogenic agent streptozotocin (STZ) was injected intraperitoneally in Long-Evans and arginine vasopressin (AVP)-deficient Brattleboro rats. Twenty-eight days later both strains had a bradycardia and systolic hypotension; STZ-treated Brattleboro rats also had diastolic hypotension. The vasopressin (V1-receptor) antagonist, d(CH2)5[Tyr(Et)]DAVP, had no effect on resting blood pressure (BP) or heart rate (HR) in either strain of rat, indicating the relative maintenance of diastolic BP in STZ-treated Long-Evans rats was not dependent on acute vascular actions of AVP. Captopril caused a modest hypotension in all groups of rats, indicating that BP was not differentially dependent on the renin-angiotensin system in the different groups. In the presence of captopril and the ganglion blocker, pentolinium tartrate, the AVP-mediated recovery in BP was impaired in STZ-treated Long-Evans rats. During administration of d(CH2)5[Tyr(Et)]DAVP and pentolinium, the angiotensin II (ANG II)-mediated BP recovery was smaller in both groups of STZ-treated rats, indicating that this abnormality was not likely to be caused by inhibition of renin release by AVP. The abnormalities in ANG II- and AVP-mediated recovery were prevented by insulin treatment.
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PMID:Blood pressure in streptozotocin-treated Brattleboro and Long-Evans rats. 213 47

A decrease in cardiac output in patients with congestive heart failure due to dilated cardiomyopathy is compensated by stimulation of the sympathetic nervous system and the renin-angiotensin-aldosterone system. The increase in plasma norepinephrine and depletion of norepinephrine in the myocardium as well as the disturbance of beta-adrenal and baroreceptor function reflect the limits of the sympathetic nervous stimulation. Together with augmented levels of angiotensin II and vasopressin, this stimulation leads to a significant increase in systemic vascular resistance. Sustained stimulation of at least one of these mechanisms can cause further impairment of the left ventricular function. The severity and prognosis of congestive heart failure due to dilated cardiomyopathy is expressed by the plasma norepinephrine concentration and by its myocardial depletion. Ultimately, activation of the compensatory mechanisms provides the basis for therapeutic approaches: 1. reduction of afterload and systemic vascular resistance and/or 2. diminution of the sympathetic nervous activity. For about the last ten years, ACE inhibitors have been used as pharmacological treatment in addition to positive inotropic and vasodilating substances. Captopril, one of the first orally applicable drugs, reduces left ventricular filling pressure, pulmonary capillary pressure, systemic vascular resistance and increases the cardiac output. Beside the hemodynamic improvement, a decrease in plasma norepinephrine and aldosterone can be observed. Vasodilators and alpha-blocking agents can also reduce afterload and systemic vascular resistance in patients with congestive heart failure due to dilated cardiomyopathy, and may lead to hemodynamic improvement. The main limitations of their long-term application are relatively short duration of action, reflex activation of the renin-angiotensin system due to vasodilation and induction of tolerance.
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PMID:[Sympathetic activity in patients with heart failure due to idiopathic dilated cardiomyopathy: effect of ACE inhibitors and other vasodilators]. 219 17

The mechanisms by which captopril inhibits vasopressin-stimulated osmotic water flow in the toad bladder have been investigated in vitro. Captopril has two possible mechanisms for the inhibitory action on the water flow, one is its stimulative effect on prostaglandin E2 (PGE2) biosynthesis by inhibition of kininase II activity, the other, is a direct effect on water flow independent of PGE2. Captopril inhibited the vasopressin-, cyclic adenosine monophosphate- and 3-isobutyl-1-methyl-xanthine-stimulated water flow. The inhibition of water flow by bradykinin was enhanced by captopril. These data indicate that captopril increased the amount of bradykinin in toad bladder cells resulting in the production of PGE2 which inhibited the increase in water flow induced by vasopressin. The inhibitory effect of captopril, however, also occurred in the presence of indomethacin, when the production of PGE2 was attenuated. Thus, it was concluded that captopril inhibits the vasopressin-stimulated water flow indirectly by inhibiting the degradation of bradykinin and thereby enhancing the production of PGE2, and directly at a site following the production of cyclic adenosine monophosphate by vasopressin.
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PMID:Mechanisms for the inhibition of vasopressin-stimulated water flow by captopril in the toad bladder. 244 80

A study was made of the effect of a single intake of captopril on the neurohumoral mechanisms of the regulation of renal circulation in 25 patients with essential hypertension (EH). Captopril induced an increase of the effective renal blood flow (ERB) and of the effective renal plasma flow along with a considerable lowering of the renal vascular resistance. No relationship was found between these changes and the time course of changes in the activity of plasma renin, aldosterone and vasopressin concentration in blood plasma. The relationship was established between the changes in the ERB and the time course of changes in baroreceptor sensitivity that significantly increased in the majority of EH patients under the effect of captopril.
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PMID:[Neurohumoral mechanisms regulating renal blood circulation in patients with hypertension undergoing captopril block of angiotensin-converting enzyme]. 257 61

We studied the hemodynamic effects of vasopressin and the renin-angiotensin system in an animal model of high output heart failure in conscious rats (aorto-caval fistula). We found significantly elevated levels of plasma renin concentration (p less than 0.025), norepinephrine (p less than 0.02), and up to 4 to 5 times higher values of vasopressin (p less than 0.002) in the rats with heart failure as compared with control animals. In contrast to the control rats that had a normally functioning osmoreceptor system, we found an inverse relationship between plasma osmolality and arginine vasopressin in the rats with heart failure in association with edema. Using a specific antagonist of the pressor activity of vasopressin, we found no significant effect on heart rate, mean arterial pressure, cardiac output (thermodilution), and peripheral vascular resistance in the control animals and in the rats with aorto-caval fistula. Captopril resulted in a significant fall of mean arterial pressure in the rats with shunt (p less than 0.001). The coincidence of high values of vasopressin and, in a number of animals, low plasma osmolalities and edema suggests a role of vasopressin in the formation of edema and in the development of "dilutional hypo-osmolality."
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PMID:Vasopressin and renin in high output heart failure of rats: hemodynamic effects of elevated plasma hormone levels. 258 Jan 26

The validity of using EXP6803, a nonpeptide angiotensin II (AII) receptor antagonist, and KAA8, an AII monoclonal antibody, as specific tools for studying the physiology of AII has been established previously. In this study, we used these specific probes to examine the role of blocking AII formation in the antihypertensive effect of captopril in conscious renal artery-ligated rats (RALRs), a high renin, renal hypertensive model. Mean arterial pressure and plasma renin activity in a typical group of RALRs averaged 175 +/- 5 mm Hg and 28.2 +/- 6.2 ng of angiotensin 1 per ml/hr (n = 6), respectively. The antihypertensive effect of captopril (3 mg/kg i.v.) was determined in RALRs given either EXP6803 (30 mg/kg + 2 mg/kg/min i.v.) or KAA8 (10 mg + 1 mg/min i.v. per rat) with the corresponding vehicle-treated RALRs. These doses of EXP6803 and KAA8 were very effective in blocking the pressor response to AII but not to norepinephrine or vasopressin in RALRs. Captopril decreased mean arterial pressure by 44 +/- 2 and 53 +/- 8 mm Hg in the groups treated with the vehicles of EXP6803 (n = 5) and KAA8 (n = 5), respectively. In the presence of EXP6803 (n = 5) or KAA8 (n = 5), the antihypertensive effect of captopril was almost or totally abolished. Indomethacin did not alter the antihypertensive effect of captopril. These results suggest that the antihypertensive effect of captopril in conscious RALRs is due mainly to the blockade of AII formation. Furthermore, circulating AII rather than locally formed AII appears to play a major role in maintaining hypertension in hypertension in RALRs.
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PMID:Antihypertensive mechanism of captopril in renal hypertensive rats: studies with a nonpeptide angiotensin II receptor antagonist and an angiotensin II monoclonal antibody. 266 2


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