Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hemorrhage and hemorrhagic hypotension have been shown to be potent stimulators of renin release. However, the relationship between angiotensinogen consumption and angiotensinogen production has yet to be completely defined during this type of circulatory stress. Peripheral renin activity increased progressively as the blood pressure was decreased stepwise by hemorrhage to 50 mmHg and remained elevated throughout the shock phase of the experiment. Angiotensinogen did not change from control (809 ng/ml) throughout hemorrhabic hypotension and shock. During hemorrhagic hypotension, with the infusion of the angiotensin antagonist, [1-sarcosine, 8-alanine]angiotensin II, angiotensinogen concentration fell progressively from 693 to 208 ng/ml at 50 mmHg. Intravenous angiotensin II infused continuously after the mean blood pressure reached 50 mmHg significantly elevated plasma angiotensinogen concentration. In conclusion, during hemorrhagic hypotension and shock, the kidney and the liver appeared capable of maintaining elevated plasma renin activity and adequate plasma renin substrate, angiotensinogen, respectively. The mechanism responsible for the maintenance of plasma angiotensinogen is suggested to involve a positive-feedback effect of angiotensin II on the liver.
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PMID:Renin response and angiotensinogen control during graded hemorrhage and shock in the dog. 98 15

1. Isolated rat kidneys were perfused at a constant pressure of 90 mmHg in a single-pass system with either a cell-free medium or a suspension of washed bovine red blood cells, free of the components of the renin-angiotensin system. In red blood cell perfused kidneys renal haemodynamics and sodium reabsorption corresponded closer to values observed in the intact rat than in cell-free perfused kidneys. 2. In red blood cell-perfused kidneys in the absence of plasma renin substrate autoregulation of renal blood flow was almost complete at pressures above 90 mmHg, provided that perfusion pressure was changed rapidly. 3. Renin release varied inversely with perfusion pressure within a pressure range from 50 to 150 mmHg; the greatest changes of renin release occurred, when perfusion pressure was reduced from 90 to 70 mmHg; maximal stimulation of renin release was observed at 50 mmHg. After reduction of perfusion pressure, renin release immediately started to rise and reached a new level within 5 min. Local reduction of perfusion pressure in small arteries and arterioles by the injection of microspheres induced a short-lasting decrease in renal plasma flow and a transient stimulation of renin release. 4. High concentrations of furosemide stimulated renin release by a direct intrarenal mechanism. 5. Isoproterenol stimulated renin release in low concentrations without a concomitant vasodilation, whereas high concentrations induced an increase in both renal plasma flow and renin release. The effects of isoproterenol were completely blocked by propranolol. 6. Sodium nitroprusside induced similar increases in renal plasma flow, as did high concentrations of isoproterenol, but only a small and slow increase in renin release was observed. 7. Angiotensin II (AII) suppressed renin release in concentrations corresponding to plasma levels measured in the intact rat independently of its vasoconstrictor effects, whereas vasopressin in antidiuretic concentrations did not affect renin release. 8. AII, AI, synthetic tetradecapeptide renin substrate (TDP), crude and purified rat plasma renin substrate induced a dose-dependent reduction in renal plasma flow. SQ 20 881, a competitive inhibitor of converting enzyme, and low doses of 1-Sar-8-Ala-AII (saralasin), a competitive antagonist of AII, did not change renal plasma flow, whereas high concentrations of saralasin had a vasoconstrictor effect on their own. 9. Saralasin inhibited the vasoconstrictor effects of AII and TDP to a similar degree. SQ 20 881 inhibited the vasoconstrictor effects of AI and purified renin substrate, but did not influence the actions of TDP and the crude renin substrate preparation. 10. From these data it is concluded, that AI is converted into AII within the kidney at a rate of 1-2%. The vasoconstriction induced by the crude renin substrate probably does not involve the AII receptors. TDP may act by itself on the AII receptors or via the direct intrarenal formation of AII...
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PMID:Regulation of renin release and intrarenal formation of angiotensin. Studies in the isolated perfused rat kidney. 98 7

1. The effect of infusions of equimolar doses of angiotensin II (AII) and of Des -angiotensin II (heptapeptide) on plasma renin activity, blood pressure and plasma aldosterone were compared in normal anaesthetized dexamethasone-suppressed dogs. 2. Plasma renin activity was equally suppressed by both compounds. The increase in blood pressure induced by the heptapeptide averaged 43-62% of the increase during AII infusions. No significant differences in aldosterone increase were observed between AII and the heptapeptide. Plasma aldosterone, however, dropped significantly faster in heptapeptide-treated dogs after the end of the infusions. 3. Sar -Ala -angiotensin II (saralasin, 400 pmol min-1 kg-1) suppressed plasma aldosterone that was stimulated by heptapeptide (20 pmol min-1 kg-1) completely. The same angiotensin antagonist had only a moderate effect on plasma aldosterone stimulated by AII. After stopping the antagonist infusion, plasma aldosterone rose significantly higher in dogs infused with AII than in those receiving the heptapeptide. 4. The results demonstrate differences between the effects of AII and the heptapeptide both on blood pressure and on plasma aldosterone. They do not support the hypothesis that the heptapeptide may be the main mediator of aldosterone secretion.
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PMID:Studies on the effect of angiotensin II and of Des -angiotensin II on blood pressure, plasma renin activity and plasma aldosterone in the dog. 107 93

The role of the renin-angiotensin system in the maintenance of arterial pressure following hemorrhage was studied in conscious dogs. Hemorrhage (20 ml/kg body wt) decreased the mean arterial pressure, but compensatory mechanisms partially restored the arterial pressure toward normal. Plasma renin activity increased more than twofold following hemorrhage. To evaluate the role of endogenous angiotensin II in this compensatory response, a specific competitive antagonist of angiotensin II, 1-sarcosine-8-alanine-angiotensin II, was infused intravenously at 6.0 mug/kg min-1 for 30 min; the mean posthemorrhage arterial pressure decreased from 102 plus or minus 7 mmHg to 80 plus or minus 6 mmHg after 15 and 30 min of analog infusion (P less than 0.01 for both values). After a recovery period of 60 min, arterial pressure returned to pre-infusion levels. These results suggest that angiotensin II plays an important role in the short-term maintenance of arterial pressure following hemorrhage in the conscious animal.
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PMID:Arterial pressure regulation during hemorrhage: homeostatic role of angiotensin II. 114 26

Hypertension was produced in rabbits by constricting the left renal artery; in nine rabbits the opposite kidney was removed and in eight rabbits the opposite kidney was left intact. To investigate the role of angiotensin II (A-II), 1-sarcosine-8-alanine angiotensin II, a competitive antagonist of A-II, was infused at 6 mug/min per kg body wt for 30 min. In a control group of seven unilaterally nephrectomized rabbits mean arterial pressure averaged 81 mmHg and infusion of the A-II antagonist did not alter the arterial pressure. In a group of Na-depleted rabbits, arterial pressure decreased from 81 to 63 mmHg (P less than 0.01) in response to the A-II analogue. Thirty days after renal artery constriction, seven of the nine one-kidney hypertensive rabbits had normal values for plasma renin activity (PRA) and during infusion of the A-II antagonist arterial pressure was unchanged. However, two rabbits had elevated PRA and the arterial pressure decreased during infusion of the angiotension analogue. In the two-kidney hypertensive rabbits, PRA was normal and arterial pressure was unchanged by infusion of the A-II antagonist. These studies provide evidence that hypertension developed with either a high or normal A-II plasma level in the one-kidney animals; the two-kidney rabbits developed chronic hypertension in which no role for A-II could be demonstrated.
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PMID:Role of angiotensin II in experimental renal hypertension in the rabbit. 114 99

Angiotensin III (des-1-Asp-angiotensin II) is a potent steriodogenic agent in many species. The effects of the heptapeptide in the adrenal zona glomerulosa are resistant to blockade by C-terminally substituted analogues of angiotensin II (1-Sar-8-Ile- or 1-Sar-8-Ala-octapeptides). For this reason, the effects of 7-Ile-angiotensin III, a C-terminally substituted analogue of the heptapeptide, and 1-Sar-8-Ile-angiotensin II on aldosterone biosynthesis in rabbit adrenal cortical cell suspensions and on urinary aldosterone excretion in sodium-deprived rats were studied. In the vitro studies, 7-Ile-angiotensin III was a better antagonist of angiotensin II- or angiotensin III-induced steroidogenesis than was 1-Sar-8-Ile-angiotensin II. In the rats, subcutaneously administered 1-Sar-8-Ile-angiotensin II (0.9 mumoles/kg) produced prolonged blockade of the pressor responses to exogenous angiotensin II. 70Ile-angiotensin III (0.9 mumoles/kg) had no effect on resting blood pressure or on blood pressure responses to angiotensin II infusions. At the doses studied, however, 7-Ile-angiotensin III caused a marked decrease (50%) in aldosterone excretion in sodium-deprived rats, but 1-Sar-8-Ile-angiotensin II had no effect on aldosterone excretion. In the sodium-deprived rats, the administration of 7-Ile-angiotensin Ile was not associated with an acute increase in plasma renin activity, but treatment with 1-Sar-8-Ile-angiotensin II resulted in a sixfold increase in plasma renin activity, but otensin III was not associated with an acute increase in plasma renin activity, but treatment with 1-Sar-8-Ile-angiotensin II resulted in a sixfold increase in plasma renin activity. These results are consistent with a role for angiotensin III in the control of aldosterone biosynthesis.
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PMID:Selective inhibition by des-1-Asp-8-lle-angiotensin ii of the steroidogenic response to restricted sodium intake in the rat. 115 23

The vasodilatory drugs, minoxidil and hydralazine, induce renin release in the rat, man and the dog. Previous reports suggest that the rat adrenal cortex was insensitive to angiotensin stimulation. As a result these studies were designed to obtain evidence for or against the hypothesis that the control of aldosterone release in the rat is unique among mammalian species. Minoxidil and hydralazine induced a time-related increase in both serum renin activity and serum aldosterone. Minoxidil caused a dose-related, proportional increase in serum renin and aldosterone. This response was blocked by prior bilateral nephrectomy but was not affected by hypophysectomy. A competitive angiotensin antagonist, saralasin (1-Sar-8-Ala angiotensin II), impaired minoxidil-induced aldosterone release in a dose-related manner while potentiating minoxidil-induced renin release. Pretreatment with propranolol, a beta adrenergic blocking drug, impaired minoxidil-induced renin and aldosterone release. Only small changes in serum corticosterone occurred after minoxidil or hydralazine administration. These results indicate that minoxidil-induced aldosterone release was mediated by the endogenous angiotensin II formed from renin release. They also support the unanesthetized rat as an appropriate animal model for study of the renin-angiotensin-aldosterone axis and its modification by drugs.
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PMID:Vasodilating antihypertensive drug-induced aldosterone release--a study of endogenous angiotensin-mediated aldosterone release in the rat. 116 23

A radioimmunoassay for the new angiotensin antagonist, saralasin (1-Sar-8-Ala-angiotensin II), was developed and applied to pharmacologic studies in rats and hypertensive man. Specificity of the assay was established using naturally occurring angiotensins, potential saralasin metabolites, and other synthetic angiotensin analogues. Saralasin pharmacologic half-life of 3.9 min after intravenous administration to rats was similar to the biochemical half-life of 4.2 min. The pharmacologic half-life in high-renin hypertensive patients averaged 8.2 with a biochemical half-life of 3.2 min. These observations suggest that metabolites of saralasin do not accumulate in sufficient quantity in man or rat to interfere with the assay. The biochemical half-life of 3.2 min is consistent with infusion time of less than 20 min required to achieve a stable plasma concentration and pharmacologic activity of saralasin during constant saralasin infusion into hypertensive man. These studies provide a rational basis of future experimental design for saralasin and possibly other peptide analogues.
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PMID:Radioimmunoassay and pharmacokinetics of saralasin in the rat and hypertensive patients. 116 11

Acute thoracic inferior vena cava constriction results in alterations in renal hemodynamics which may explain the characteristic antinatriuretic response. Since adrenalvein-aldosterone secretion is increased within 30 minutes of acute caval constriction and elevated plasma-renin activity is found in the chronic caval dog, we sought to determine whether the renal hemodynamic alterations observed in acute caval constriction are due to the intrarenal action of angiotensin II. The renal response to acute caval constriction in dogs receiving unilateral renal arterial infusion of a specific competitive antagonist of angiotensin II, 1-sarcosine-8-alanine-agiotensin II, was studied. Effective blockade did not alter the renal hemodynamic or antinatriuretic response to acute caval constriction. As a model of chronic sodium retention, dogs with chronic congestive heart failure produced by tricuspid insufficiency and pulmonary stenosis were similarly studied. Effective renal blockade to antiotensin II did not affect renal hemodynamics or urinary sodium excretion. The renal hemodynamic and antinatriuretic responses to acute caval constriction and chronic congestive heart failure are not dependent on the intrarenal action of angiotensin II.
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PMID:Renal blockade to angiotensin II in acute and chronic sodium-retaining states. 118 90

The ability of the immature kidney to autoregulate blood flow was investigated. Renal blood flow was measured by electromagnetic flowmeter. In six puppies, selective blockade of the intrarenal effects of angiotensin II (AII) by [1-sarcosine, 8-alanine]angiotensin II (anti-AII) administered into the renal artery did not change renal blood flow. During selective renal AII blockade, intravenous AII raised perfusion pressure from 76 +/- 2 to 100 +/- 6 mmHg. Renal blood flow increased from 1.59 +/- 0.29 to 1.98 +/- 0.59 ml/g kidney per min, but returned to control levels within 40 s in spite of persistent arterial pressure elevation. In another group of seven puppies, renal blood flow remained constant despite reduction of renal perfusion pressure by aortic constriction to 60 mmHg. In two of these seven puppies intrarenal anti-AII did not abolish autoregulation. Autoregulation of renal blood flow occurs in the puppy and is not influenced by inhibition of angiotensin. The renin-angiotensin system does not appear to be involved in the normal regulation of renal blood flow in the puppy.
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PMID:Autoregulation of renal blood flow in the puppy. 119 Mar 43


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