Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.15.1 (ACE)
18,300 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The possible role of vascular angiotensin converting enzyme (ACE) is examined in vitro and in vivo. In helically cut strips of arteries isolated from dogs, contractions induced by angiotensin (ANG) I are suppressed by ACE inhibitor or ANG II antagonist. This indicates that vascular ACE contributes to the local formation of ANG II. In two-kidney, one-clip hypertensive rats, plasma-renin activity (PRA) rises rapidly with the elevation of blood pressure, then decreases gradually, despite sustained high blood pressure. Renin activity in the aorta also increases with the development of hypertension and then decreases in parallel with PRA. ACE activity in plasma does not change before or after the unilateral occlusion of the renal artery until after 16 weeks, whereas the enzyme activity in the aorta significantly increases. The conversion rate calculated from the pressor responses, and from the constricting effects of ANG I and ANG II, both in situ and in helically cut strips obtained from chronic hypertensive rats with increased vascular ACE activities, are significantly higher than those obtained from normotensive rats. Vascular ACE, which can effectively produce ANG II from ANG I locally, appears to play an important role in the maintenance of chronic hypertension.
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PMID:Vascular angiotensin converting enzyme in the development of renal hypertension. 243 92

To clarify the relationship between kallikrein-kinin and renin-angiotensin systems, glandular kallikrein, renin and angiotensin converting enzyme in the submandibular gland, the kidney and plasma were investigated in streptozotocin diabetic and spontaneously hypertensive rats. Kallikrein content in the submandibular gland, the kidney and plasma of diabetic rats was found to be decreased compared with nondiabetic controls. Renin activity in diabetic rats was also reduced in the submandibular gland, but the activity showed no significant changes in the kidney and plasma. The activity of angiotensin converting enzyme (ACE) in plasma significantly increased in diabetic rats. On the other hand, kallikrein content in hypertensive rats was depressed in the kidney, while the content was unchanged in the submandibular gland and plasma. Renin activity in hypertensive rats was found to be higher than that of normotensive rats in the submandibular gland, but the activity showed no remarkable changes in the kidney and plasma. ACE activity in plasma markedly decreased in hypertensive rats in contrast to diabetic rats. In hypertensive-diabetic rats, changes in the levels of these enzymes in tested materials were similar to those of diabetic rats. From these results it is reasonable to assume that (1) reduced kallikrein generation and elevated ACE activity may induce impaired kinin formation and contribute to the development of diabetes mellitus apart from the presence of hypertension and (2) low kallikrein content in the kidney could cause hypertension.
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PMID:Glandular kallikrein, renin and angiotensin converting enzyme of diabetic and hypertensive rats. 255 14

There has been considerable interest in the existence of an intrarenal renin-angiotensin system and its physiological implications. Recent demonstrations of renin, angiotensinogen and angiotensin converting enzyme messenger (m)RNAs in the kidney have provided strong evidence for the presence of an independent local system. This has been further supported by the demonstration of tissue-specific regulation of renin and angiotensinogen mRNA expression which may lead to differential systemic and intrarenal angiotensin activities. Using in situ hybridization, we have localized the intrarenal sites of gene expression and possible angiotensin production. One major site appears to be the proximal tubule, where local angiotensin can regulate sodium reabsorption and urine pH. Renin and angiotensinogen mRNA expressions are regulated by several common factors. In particular, sodium depletion stimulates the expression of both genes in the kidney, increasing the production of intrarenal angiotensin that is important in maintaining sodium homeostasis. Renal renin and angiotensinogen mRNA levels are altered in experimental heart failure and the spontaneously hypertensive rat (SHR). These changes in intrarenal renin and angiotensinogen mRNA expression may be important in the renal pathophysiology of these diseases.
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PMID:Molecular biology and pathophysiology of the intrarenal renin-angiotensin system. 255 71

The cardiovascular actions of a renin inhibitor, U-71038 (Boc-Pro-Phe-N-MeHis-Leu psi [CHOHCH2]Val-Ile-Amp), and of an angiotensin converting enzyme (ACE) inhibitor, captopril, were determined in conscious sodium-depleted cynomolgus monkeys. Cardiac output was measured with a thermodilution technique. The hypotension induced by U-71038 was associated with a significant reduction in total peripheral resistance without alteration in cardiac output or the heart rate. A similar reduction in total peripheral resistance was observed after captopril at a dose which caused hypotension equivalent to that elicited by U-71038. The latter effects were not accompanied by significant alterations in cardiac output or the heart rate. The glomerular filtration rate was measured by the plasma disappearance of 125I-sodium iothalamate. Renin or ACE inhibition adequate to cause equivalent hypotensive responses did not change the glomerular filtration rate to a significantly different degree. The systemic and renal haemodynamic profiles of U-71038 and captopril appear to be similar, suggesting that renin and ACE inhibition elicit fundamentally similar cardiovascular effects in conscious sodium-depleted cynomolgus monkeys via a decreased formation of angiotensin II (Ang II).
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PMID:Systemic and renal haemodynamic effects of renin or angiotensin converting enzyme inhibition in non-human primates. 266 13

Renin-like enzyme and angiotensin converting enzyme (ACE) were identified and their specific activities measured in cardiac tissues of spontaneously hypertensive rats (SHR) and their Wistar-Kyoto (WKY) normotensive controls. In addition, the enzyme activities were determined following administration of hypotensive drugs. The pH optima of cardiac renin-like enzymes were identical with those in vascular walls, the specific activity being higher in the heart. Cardiac ACE revealed similarities with the venous wall enzyme. The highest specific cardiac renin-like activity was found in the septum and that of ACE in atria/auricles. Both enzyme values were lower in the hearts of SHR than in those of normotensive controls. Following nifedipine treatment, specific renin-like activities increased in all cardiac structures studied (P less than 0.01); with nitrendipine and muzolimine less pronounced elevations were obtained. Administration of these three hypotensive drugs resulted in a stimulation of ACE in all the cardiac structures except in atria/auricles, where their activities were lowered.
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PMID:Suppression of renin-angiotensin system in the heart of spontaneously hypertensive rats. 282 Dec 5

Renin secretion has been studied in the past at the level of the whole kidney, but the control of the genetic basis of renin synthesis is poorly understood. We have studied the regulation of renin gene expression in the fetus and also in the adult rat in response to angiotensin converting enzyme (ACE) inhibition with enalapril in the presence and absence of angiotensin II (AII). In the fetus, vascular smooth muscle cells of the renal afferent arteriole and feeder vessels contain renin mRNA and immunostain for renin. With maturation, these vessels progressively lose the capacity to synthesize renin, and only the juxtaglomerular cells retain this capacity in the adult. However, in response to ACE inhibition, the adult renal feeder vessels acquire the capacity to synthesize and secrete renin within 7 days. This effect is partially reversed with co-administration of AII. In order to study renin biosynthesis and secretion at the cellular level, we have developed a new method of study of individual renin-secreting cells, the reverse hemolytic plaque assay (RHPA). Utilizing this method, we have demonstrated that ACE inhibition with enalapril increases the number of renin secreting cells by over 15-fold at physiologic calcium concentrations. Enalapril also induced a 3-fold increase in the amount of renin released as estimated by the area of the hemolytic plaques formed. Transmission electron microscopy (EM) of the renin-secreting cell at the center of a hemolytic plaque demonstrates modified vascular smooth muscle cells with cytoplasmic granules. In summary, ACE inhibition stimulates renin mRNA accumulation and redistributes renal renin content toward that observed in early fetal life. AII inhibits renal renin mRNA accumulation. ACE inhibition increases the number of renin secreting cells as well as the amount of renin secreted by each cell. The individual renin secreting cell is a modified vascular smooth muscle cell with cytoplasmic secretory granules. Further studies of the cellular pathways for renin secretion can be provided by EM immunocytochemistry of the individual renin secreting cell.
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PMID:Cell and molecular studies of renin secretion. 285 75

Renin, angiotensinogen, and converting enzyme were detected in 10 normal human pituitary glands by immunohistochemical techniques. Renin was stained by polyclonal and monoclonal antibodies directed against human renin, and an antibody directed against the renin prosegment revealed the presence of prorenin. Immunoreactive angiotensinogen and angiotensin I-converting enzyme were found in the same cells as renin. Using serial sections and double immunohistochemical labeling with a PRL antiserum, all of the proteins of the renin-angiotensin system appeared to be localized within the lactotroph cells, and no component of the renin system was detected in any of the other pituitary cells. Renin, angiotensinogen, and angiotensin I-converting enzyme also were found in 6 PRL-secreting adenomas as well as in a mixed PRL/GH-secreting adenoma. The renin content of a PRL adenoma was about 1/100th that of a normal kidney. Renin activity could be blocked by an anticatalytic human renin antibody. No renin, angioten-sinogen, or angiotensin I-converting enzyme was found in 6 GH-secreting adenomas, 1 corticotroph adenoma, or 10 nonsecreting pituitary adenomas. The colocalization of proteins of the renin-angiotensin system suggests production of angiotensin II within the lactotroph cells and favors the hypothesis of a paracrine action of this peptide.
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PMID:Presence of renin, angiotensinogen, and converting enzyme in human pituitary lactotroph cells and prolactin adenomas. 301 40

The possible role of the renin-angiotensin system in the maintenance of hypertension in two-kidney, one clip hypertensive rats was studied. Plasma renin activity rose rapidly and markedly in association with the elevation of blood pressure and then decreased gradually, although blood pressure remained high. Renin activity in the lung, aorta, and mesenteric artery also increased with the development of hypertension and then decreased in a way similar to that of plasma renin activity at the chronic stage of hypertension. Plasma angiotensin converting enzyme activity did not change significantly until 16 weeks after unilateral renal artery clipping, whereas vascular angiotensin converting enzyme activity significantly increased at the chronic, but not the acute, stage of hypertension. In chronically renal hypertensive rats, 1-sarcosine, 8-isoleucine angiotensin II or enalapril, an angiotensin converting enzyme inhibitor, lowered the blood pressure and enalapril also lowered the angiotensin converting enzyme activity of vascular tissues. The constrictor effect of angiotensin I was greater in isolated arteries from chronically hypertensive rats than in those from age-matched normotensive rats. These results suggest that the vascular renin-angiotensin system plays an important role in the maintenance of two-kidney, one clip hypertension. Elevated vascular angiotensin converting enzyme activity appears to increase local production of angiotensin II, which results in vasoconstriction by acting directly and indirectly through adrenergic nerves on vascular smooth muscle.
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PMID:Vascular renin-angiotensin system in two-kidney, one clip hypertensive rats. 301 74

Evidence is accumulating that demonstrates the presence of local renin-angiotensin systems, in addition to the established circulating renin-angiotensin system. Renin-like substances, immunoreactive angiotensins, and angiotensin II receptors have been identified throughout the vasculature. Local tissue concentrations of angiotensin converting enzyme (ACE) inhibitors, rather than serum concentrations, may be more important in determining the magnitude and duration of the long-term cardiac and vascular response to this group of drugs. Certain structural and chemical properties of the ACE inhibitors may provide unique effects at various tissue sites.
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PMID:Vascular renin-angiotensin system in hypertension. New insights into the mechanism of action of angiotensin converting enzyme inhibitors. 321 57

All components of the renin-angiotensin system (RAS), including angiotensinogen messenger RNA (mRNA), renin-like activity (RLA), renin mRNA, angiotensin II (A II) immunoreactivity and angiotensin converting enzyme, have been found in the whole rat ovary and A II receptors have recently been localized to ovarian follicles. Our study was designed to test further which part of the ovary can produce renin. Renin mRNA was detected in the gonadotropin-stimulated rat's corpus luteum using in situ hybridization histochemistry techniques. No positive signal was detected in theca or granulosa cells. These results indicate ovarian renin gene expression in rat luteal cells, where the renin molecule is probably produced, and support our concept of an intrinsic ovarian RAS.
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PMID:In situ hybridization identifies renin mRNA in the rat corpus luteum. 333 36


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