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)

Mean arterial pressure (BP) was measured in conscious, spontaneously hypertensive rats (SHR). Oral administration of the angiotensin I-converting enzyme inhibitor (ACEI) CGS 16617 significantly lowered BP. In contrast, the thromboxane synthetase inhibitor (TxSI) CGS 12970 lacked an antihypertensive action in SHR. When administered concurrently, the TxSI significantly potentiated the antihypertensive actions of the ACEI. Inhibition of thromboxane synthetase did not potentiate the antihypertensive actions of metoprolol or verapamil, indicating that a specific interaction exists between a TxSI and an ACEI. The antihypertensive actions of CGS 16617 also were potentiated by the cyclooxygenase inhibitor indomethacin, a result suggesting that CGS 12970 may enhance the action of CGS 16617 by inhibiting the action of vasoconstrictor prostaglandins produced after administration of an ACEI. The potentiation of the antihypertensive actions of CGS 16617 by CGS 12970 remained unaffected by either the kallikrein inhibitor aprotinin or a bradykinin receptor antagonist. Thus, although the interaction between an ACEI and a TxSI is a prostaglandin-dependent mechanism, it is not mediated by endogenous kinins. Inhibition of thromboxane synthetase significantly stimulated renin release and significantly attenuated the pressor response to exogenously administered angiotensin II. An increase in the dependency of BP upon the renin-angiotensin system and attenuation of the vascular actions of angiotensin II may serve to explain the potentiation of the antihypertensive action of ACEI after inhibition of thromboxane synthetase. The interaction between ACEI and TxSI was not restricted to SHR, because a TxSI potentiated the actions of an ACEI in both normotensive and deoxycorticosterone acetate/Na hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of thromboxane synthetase potentiates the antihypertensive action of an angiotensin-converting enzyme inhibitor by a prostaglandin-dependent but kinin-independent mechanism. 192 Jan 18

The positive inotropic response to angiotensin I and II in cardiac tissue of most mammalian species, as well as the exact site in the heart for conversion of local and systemic angiotensin I into angiotensin II, remains to be elucidated. In isolated cat papillary muscles, angiotensin I and angiotensin II (0.1 nM to 1 microM, 35 degrees C, 1.25 mM Ca2+) increased, in a dose-dependent manner, peak twitch tension with typical slight prolongation of twitch duration. This typical response did not necessitate the presence of an intact endocardial endothelium (EE), as a similar response was observed in muscles where the EE had been damaged by a 1-second exposure to 0.5% Triton X-100. After addition of captopril, an angiotensin converting enzyme inhibitor, the positive inotropic response to angiotensin I was completely abolished, both in the presence and the absence of an intact EE. Hence, the heart possesses angiotensin converting enzyme, which mediates the positive inotropic response to angiotensin I. An intact EE was not a prerequisite for this response; thus, myocytes as well as nonmyocytes may be possible locations (in addition to the EE) for angiotensin converting enzyme. In the presence of an intact EE, and after addition of captopril, the positive inotropic response to angiotensin II was significantly diminished (desensitization). By contrast, in the absence of an intact EE, but also after addition of captopril, the positive response to angiotensin II was potentiated (sensitization). Both desensitization and sensitization (in the presence or absence of an intact EE, respectively) of the response to angiotensin II induced by the addition of captopril were inhibited by indomethacin, a cyclooxygenase inhibitor, suggesting a role for prostaglandins.
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PMID:Does endocardial endothelium mediate positive inotropic response to angiotensin I and angiotensin II? 211 40

In order to determine the possible role of prostaglandins in the abnormal cough reflex in patients with dry cough, the effects of a cyclooxygenase inhibitor on cough symptoms were examined. This was measured by a cough symptom score and by the cough reflex sensitivity to inhaled capsaicin in a double blind, randomized, cross-over study comparing the effects of placebo with sulindac, 200 mg daily for 1 week. We studied six hypertensive patients with angiotensin converting enzyme inhibitor-associated cough and six patients with an idiopathic, dry, unproductive cough, all of whom had an increase in the sensitivity of the cough reflex. There was no change in blood pressure control in the hypertensive patients during sulindac therapy. The patients with the angiotensin converting enzyme-associated cough had a significant reduction in the cough symptom score and also a significant increase in the dose of capsaicin causing two or more coughs (threshold sensitivity) and that causing five or more coughs (near maximum response) during sulindac therapy as compared to placebo. In those patients with idiopathic, dry, unproductive cough, sulindac did not alter the symptom of cough or the cough reflex response to capsaicin. These results suggest that prostaglandins may be involved in cough associated with angiotensin converting enzyme inhibitor therapy, but are less likely to be important in the pathogenesis of more common dry coughs of unknown cause.
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PMID:The effect of sulindac on the abnormal cough reflex associated with dry cough. 221 52

Studies have examined renal function to determine the role of the kidney in the pathogenesis and maintenance phases of hypertension in the Okamoto-Aoki strain of spontaneously hypertensive rat (SHR). As compared to age-matched Wistar-Kyoto rats (WKY), 4- to 6-week old SHR are moderately hypertensive and have a reduced glomerular filtration rate (GFR) and renal blood flow (RBF), and an increased renal vascular resistance. Cross-breeding studies indicate the reduction in RBF and GFR in young SHR is genetically linked to the hypertension and thus may be of primary pathogenetic importance. The combination of an elevated vascular resistance and reduced RBF and GFR in young SHR implicates increased activity of a vasoconstrictor system(s), decreased activity of a vasodilator system(s), or both. Observations from several laboratories support the notion that endogenous angiotensin II contributes to the renal vasoconstriction in young SHR during the developmental phase of hypertension. Acute and chronic inhibition of angiotensin converting enzyme reduce arterial pressure, reduce renal vascular resistance and increase renal blood flow in young and adult SHR. Renal vascular tone in SHR is more dependent on angiotensin converting enzyme activity than that in WKY. The ability of angiotensin converting enzyme inhibitors to produce renal vasodilation may be responsible, at least in part, for its antihypertensive effects. Other studies indicate that renal vascular reactivity to angiotensin II is exaggerated in young SHR. The strain differences in renal reactivity to angiotensin II can be abolished by cyclooxygenase inhibition with indomethacin, indicating that endogenous prostanoids counteract some of the constrictor action of angiotensin II, with more pronounced buffering activity in WKY.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of angiotensin in the renal vasoconstriction observed during the development of genetic hypertension. 225 85

Incubation of cultured bovine pulmonary artery endothelial cells with 200 microM of 3-isobutyl-1-methylxanthine (IBMX) for 24 hr produced a five- to tenfold increase in cellular angiotensin converting enzyme activity (ACE) above that of untreated control cells. A lesser increase was observed in medium ACE. Other methylxanthines produced a similar, but less marked, effect. The elevation of ACE seemed to require de novo protein synthesis since it was reduced by 0.1 microgram/ml cycloheximide. Elevation of cellular cAMP was detected at 30 min after introduction of IBMX, then rapidly returned to control levels at 1 hour, while elevation in cellular ACE at 24 hr required contact with IBMX for at least 2 hr. Hence, the transient elevation in cAMP is unlikely to be the cause of the elevation of ACE. Phorbol ester and synthetic diacyl glycerol OAG, activators of protein kinase C, did not elevate ACE. Indomethacin, at a concentration known to inhibit cyclooxygenase activity, had no effect on the elevation of ACE. The elevation of ACE by IBMX was not affected by the calcium channel blocker verapamil or the calcium chelator EGTA. In contrast, the effect of IBMX was totally abolished by the calmodulin inhibitors trifluoperazine and calmidazolium. The data show that IBMX elevates endothelial cell ACE and suggest that the elevation is mediated by a calcium-calmodulin complex. The studies demonstrate a novel effect of methylxanthines on endothelial cells in culture.
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PMID:Elevation of angiotensin converting enzyme by 3-isobutyl-1-methylxanthine in cultured endothelial cells: a possible role for calmodulin. 245 40

The goal of the present study was to evaluate the effects of endothelin, a newly discovered very potent vasoconstrictor secreted by endothelial cells, on the coronary vascular bed. For this purpose, the effects of endothelin injected intracoronarily were tested in open-chest anesthetized dogs with the circumflex coronary artery cannulated and perfused at a constant pressure of 100 mm Hg. Circumflex blood flow, transmural distribution of coronary blood flow (radioactive microspheres), circumflex coronary artery diameter (piezoelectric crystals), and circumflex luminal surface area were measured. Endothelin decreased coronary blood flow by 30% and 61% with doses of 1 and 3 micrograms, respectively. A dose of 10 micrograms was lethal. The decrease of coronary blood flow was larger in the subepicardium than in the subendocardium, which explains that the endocardial-epicardial blood flow ratio increased from 1.27 +/- 0.05 to 1.98 +/- 0.23 (p less than 0.001) with a dose of 3 micrograms endothelin. Circumflex surface area decreased by 7% (p = NS) and 20% (p less than 0.01) with doses of 1 and 3 micrograms endothelin, respectively. The action of endothelin was not modified by the concomitant alpha-adrenergic blockade, serotonergic blockade, angiotensin converting enzyme inhibition, or cyclooxygenase inhibition. We conclude that endothelin is a potent coronary vasoconstrictor with a selective effect on the subepicardium. At least part of the increase of coronary vascular resistance is due to a constriction of the large coronary arteries. Further studies are required to determine the physiopathological role of endothelin, especially in coronary vasospasm.
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PMID:Effects of endothelin on the coronary vascular bed in open-chest dogs. 268 Jan 49

To evaluate the relative contribution of endogenous vasoactive compounds to maintenance of increased renal vascular resistance in neonatal obstructive nephropathy, cardiac output and renal blood flow were measured using radioactive microspheres in 25 +/- 3 day-old guinea pigs subjected to unilateral partial ureteral constriction within the first two days of life. Mass and renal blood flow of the obstructed kidney were significantly lower than those of the contralateral kidney. Following a control period, thromboxane synthesis was blocked by infusion of OKY-046, after which prostaglandin synthesis was inhibited by indomethacin. In a separate group of animals, angiotensin converting enzyme inhibitor, MK-422, was infused before or after administration of OKY-046. While neither OKY-046 nor indomethacin had a consistent effect on vascular resistance, infusion of MK-422 resulted in selective reduction of renal vascular resistance of the obstructed kidney compared to resistance in the intact kidney and other vascular beds. Removal of the contralateral kidney at the time of ureteral constriction in an additional group of animals resulted in hypertrophy and vasodilation of the obstructed kidney which was not altered by thromboxane or cyclooxygenase inhibition. We conclude that in the neonatal kidney subjected to ipsilateral chronic partial ureteral obstruction, vasoconstriction is mediated at least in part by angiotensin II, but not by thromboxane. Furthermore, vasodilation of the obstructed kidney resulting from contralateral nephrectomy is not dependent on prostaglandin synthesis. Renal vascular resistance of the kidney with prolonged partial ureteral constriction in early development thus appears to be inversely related to renal growth and is not significantly mediated by endogenous prostanoids.
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PMID:Contribution of endogenous vasoactive compounds to renal vascular resistance in neonatal chronic partial ureteral obstruction. 301 45

The effect of indomethacin (INDO), an inhibitor of prostaglandin (PG) cyclooxygenase, on pulmonary vascular permeability is unclear. We measured angiotensin converting enzyme (ACE) activity in plasma and lung lymph in order to evaluate pulmonary endothelial integrity. Eighteen sheep, anesthetized and acutely prepared for the collection lung lymph, were used in the study. Four animals (Group I) served as sham controls and were not subjected to experimental intervention. In order to minimize changes in pulmonary microvascular surface area (PMSA), left atrial blood pressure (Pla) was elevated (12-20 Torr) following the baseline period in animals in the three experimental groups. Group II (n = 4) was subjected to increased Pla only in order to assess the effects of that maneuver alone on experimental parameters. Group III (n = 3) received an infusion of buffered vehicle only during a four hour period of elevated Pla, and, thus served as a vehicle control for Group IV (n = 7) which received INDO for the same period of increased Pla. Pulmonary blood pressures, cardiac output (CO), lung lymph flow (Ql) and the ratio of lymph to plasma protein concentration (L/P) were measured in all experiments in order to independently assess changes in lung vascular permeability. While ACE activity in plasma and lymph fell in each experimental group, average ACE experimental values were unchanged from corresponding baseline values. Increased Pla caused a characteristic increase in Ql and fall in L/P in each of the experimental groups. We conclude that INDO does not alter lung fluid and protein balance by a process which involves increased pulmonary vascular permeability secondary to a loss of endothelial integrity.
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PMID:The effect of indomethacin on plasma and lung lymph angiotensin converting enzyme activity in sheep. 303 87

After uninephrectomy in the young rat, renal blood flow (RBF) increases at normal renal perfusion pressure (RPP) but not at reduced RPP. To evaluate the role of endogenous prostaglandins on these effects, RBF was measured during reduction in RPP in rats that were uninephrectomized within 1 wk of age and studied at 33-41 days of age. After acute cyclooxygenase inhibition, autoregulation improved; RBF was unchanged at normal RPP but increased at lower pressures with concomitant decrease in renal venous plasma renin activity (PRA). Prostaglandin inhibition also improved autoregulatory efficiency in acutely uninephrectomized and sham-operated young rats. Infusion of a thromboxane synthesis inhibitor had no effect on the pressure-flow relationship or on PRA, whereas angiotensin converting enzyme inhibition increased RBF at all measured RPP without affecting autoregulation. We conclude that increased RBF at normal RPP in the uninephrectomized young rat is not maintained by increased prostaglandin synthesis or decreased thromboxane- or angiotensin-dependent vasoconstriction. However, by maintaining increased vasoconstriction at reduced RPP, prostaglandin-dependent renin release reduces autoregulatory efficiency in the young rat.
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PMID:Endogenous prostaglandins modulate autoregulation of renal blood flow in young rats. 303 24

Ferret tracheal segments were infected with human influenza virus A/Taiwan/86 (H1N1) in vitro. After 4 days, the smooth muscle contractile responses to acetylcholine and to substance P were measured. The response to substance P was markedly accentuated, with a threefold increase in force of contraction at a substance P concentration of 10(-5) M, the highest concentration tested. In contrast, the response to acetylcholine was not affected by viral infection. Histological examination of tissues revealed extensive epithelial desquamation. Activity of enkephalinase (neutral metallo-endopeptidase, EC.3.4.24.11), an enzyme that degrades substance P, was decreased by 50% in infected tissues. Inhibiting enkephalinase activity by pretreating with thiorphan (10(-5) M) increased the response to substance P to the same final level in both infected and control tissues. Inhibiting other substance P-degrading enzymes including kininase II (angiotensin-converting enzyme), serine proteases, and aminopeptidases did not affect the response to substance P. Inhibiting cyclooxygenase and lipoxygenase activity using indomethacin and BW 755c did not affect hyperresponsiveness to substance P. Pretreating tissues with antagonists of alpha-adrenoceptors, beta-adrenoceptors, and H1 histamine receptors (phentolamine 10(-5) M, propranolol 5 X 10(-6) M, and pyrilamine 10(-5) M, respectively) had no effect on substance P-induced contraction. These results demonstrate that infection of ferret airway tissues with influenza virus increases the contractile response of airway smooth muscle to substance P. This effect is caused by decreased enkephalinase activity in infected tissues.
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PMID:Influenza infection causes airway hyperresponsiveness by decreasing enkephalinase. 304 36


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