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

The present experiments describe the endothelin-1 (ET-1) antagonist activity of BQ123 (cyclic D-Asp-L-Pro-D-Val-L-Leu-D-Trp) in conscious Sprague-Dawley (SD) rats, and we also examined the effect blockade of ETA receptors had on blood pressure in four experimental models of hypertension. Rats were anesthetized with methoxyflurane and instrumented with femoral arterial and venous catheters. In SD rats, BQ123 (0.1-10.0 mg/kg i.v.) administered 5 or 60 min prior to ET-1 inhibited both the magnitude and duration of the ET-1 (0.25 nmol/kg i.v.) pressor response. In addition, BQ123 (10.0 mg/kg) inhibited the pressor response evoked by administration of the ET-1 precursor, proendothelin-1 (1.0 nmol/kg). However, BQ123 (10.0 mg/kg) had no effect on the pressor response evoked by ET-3 (0.75 nmol/kg). In Wistar-Kyoto rats, BQ123 (10.0 mg/kg) reversed the hypertension produced by an infusion of ET-1 (0.01 nmol/kg/min). Administration of BQ123 produced a mild antihypertensive effect in normal- to low-renin models of hypertension, but no blood pressure lowering was observed in high-renin models of hypertension. These studies demonstrated the selectivity of the ETA receptor antagonist, BQ123 for ET-1, but not ET-3-induced pressor responses. Furthermore, ET-1 does not appear to be a major contributing factor to the maintenance of elevated levels of blood pressure in four experimental models of hypertension.
 ...
PMID:Pharmacologic characterization of an endothelinA (ETA) receptor antagonist in conscious rats. 128 97

Endothelin-1, a potent vasoconstrictor peptide with 21 amino acid residues, is released by the vascular endothelium. Plasma immunoreactive endothelin levels were measured in 23 patients with cirrhosis and in 20 healthy subjects. Concentrations were significantly lower in patients with non-uraemic cirrhosis than in normal subjects (19.4 +/- 8.9 pmol/l vs. 48.8 +/- 24.8 pmol/l, p less than 0.002). Plasma renin, aldosterone, atrial natriuretic peptide, arginine-vasopressin and catecholamines did not show significant correlations with plasma endothelin-1 levels. Furthermore, there were no significant differences in plasma endothelin levels for etiology of cirrhosis, presence of ascites or varices. These data suggest that low circulating endothelin may be involved in the development or maintenance of systemic vasodilatation in cirrhosis.
 ...
PMID:Plasma endothelin levels in cirrhotic subjects. 138 39

To evaluate the role of atrial natriuretic peptide (ANP) in exercise-related cardiovascular and hormonal adjustments in hypobaric conditions, 14 young athletes performed a maximal ergometer test in a hypobaric chamber adjusted to simulate the altitudes of sea level and 3,000 m. Plasma immunoreactive ANP levels rose from 5.89 to 35.1 pmol/l at sea level and rose significantly less (P less than 0.05), from 5.36 to 22.3 pmol/l, at simulated 3,000 m. Plasma immunoreactive amino-terminal peptide of proANP (NT-proANP) levels increased to the same extent at sea level and at simulated 3,000 m (from 240 to 481 pmol/l and from 257 to 539 pmol/l, respectively). Plasma immunoreactive aldosterone increased significantly less at simulated 3,000 m (P less than 0.05), but the changes in plasma renin were similar in both conditions. Plasma immunoreactive endothelin-1 and serum erythropoietin levels remained unchanged. In conclusion, we found a blunted ANP response to maximal exercise of ANP in acute hypobaric exposure compared with that in normobaric conditions, but no significant difference in the NT-proANP responses between the two conditions. The divergence may be due to stimulation of the elimination mechanism of ANP.
 ...
PMID:Effect of physical exercise in hypobaric conditions on atrial natriuretic peptide secretion. 141 53

We have previously proposed the ovarian ERAANPS (endothelin-rein- angiotensin-atrial natriuretic peptide system). The present study was undertaken to examine in vivo the effects of herbal medicines [Tokishakuyakusan (TS), Keishibukuryogan (KB), Shakuyakukanzoto (SK) and Unkeito (UT)] on endothelin-1 (ET), renin and angiotensin II (A II) in the ovaries, of immature rats treated with 10 IU PMS for 48 h. ET and all components of renin-angiotensin system (RAS) were found at high levels in the ovary. Concomitant treatment with PMS plus TS, KB, SK or UT, especially TS and UT, tended to decrease the ET levels in ovary, while components of RAS tended to increase. However, ET, renin and A II levels in plasma were not at all affected after treatment with TS, KB, SK or UT. These results suggest that TS, KB, SK or UT may regulate the ovarian ERAANPS.
 ...
PMID:Effects of tokishakuyakusan, keishibukuryogan, shakuyakukanzoto and unkeito on ovarian endothelin, renin and angiotensin II in pregnant mare's serum gonadotropin-treated immature rats. 151 58

We have previously shown the presence in a high concentration of endothelin-1 (ET) in the corpus luteum and renin-angiotensin system (RAS) and binding sites for atrial natriuretic peptide (ANP) in the ovarian follicle. The present study was undertaken to identify the existence of ET, renin, angiotensin II and the binding site for ANP in the ovary at proestrus and examine in vivo the effects of herbal medicines [Tokishakuyakusan (TS), Keishibukuryogan (KB), Shakuyakukanzoto (SK) and Unkeito (UT)] on them. ET, all components of RAS and binding sites for ANP were found at high levels in the ovary. TS, KB, SK and UT decreased the ET levels in ovary, while components of RAS and binding sites for ANP have the propensity to increase. However, ET, renin, angiotensin II and ANP levels in plasma were not at all affected before and after treatment with TS, KB, SK or UT. Taken together with previous observations showing the existence of ET, RAS and the binding site for ANP in the ovary, we propose here the ERAANPS (endothelin-renin-angiotensin-ANP system) in the ovary as a functional regulator. Further, these results suggest that TS, KB, SK or UT may regulate the ovarian ERAANPS.
 ...
PMID:A proposal of ovarian ERAANPS (endothelin-renin-angiotensin-atrial natriuretic peptide system) and effects of tokishakuyakusan, keishibukuryogan, shakuyakukanzoto and unkeito on the ERAANPS. 153 63

This study was conducted to determine the involvement of endogenous endothelin-1 (ET-1), a potent vasoconstricting peptide, in systemic and renal hemodynamics and in the renin-angiotensin system, by inhibiting ET-1 action with an infusion of specific ET-1 antiserum during altered sodium balance. Infusion of 1:50 diluted ET-1 antiserum, which completely inhibited renal vasoconstriction caused by exogenously administered ET-3 (0.25 to 1.0 nmol/kg), increased urinary sodium excretion (UNaV) and fractional excretion of sodium (FENa), and decreased the plasma renin concentration (PRC) without significant changes in blood pressure, heart rate, GFR, RPF, or urine volume (UV) in conscious rats fed a low-salt diet, but not those on a high-salt diet. A time-control study showed no significant changes in any of these parameters. These results suggest that during low salt intake, in comparison to high salt intake, endogenous ET is more potent. Endogenous ET may thus contribute to the adaptive modulation of sodium excretion by a renal tubular action, and of renin release in association with a change in sodium balance.
 ...
PMID:Role of endogenous endothelin in renal function during altered sodium balance. 172 59

It has been shown that in vitro angiotensin II (Ang II) potently downregulates endothelin-1 (ET-1) binding sites. In this study, we investigated in vivo the interactions between the renin-angiotensin system and ET-1. Sprague-Dawley rats were pithed, ventilated, and diastolic blood pressure (DBP) was recorded. ET-1 (1 nmol/kg) induced a biphasic response: a transient hypotension followed by a sustained increase of DBP. Captopril (5 mg/kg, i.v.) or Sar1-Ile8-Ang II (10 ng/kg/min) did not affect ET-1 responses. In other experiments, DBP was increased by infusion of methoxamine (MTX: 10, 20, 25, 32.5 micrograms/kg/min) or Ang II (50, 100, 150, 200 ng/kg/min). ET-1-induced hypotension correlated with the level of DBP (r = 0.94) for both agonists. The elevation of DBP in response to ET-1 was also related to the vascular tone but was dose-dependently attenuated by Ang II infusion when compared with MTX. Conversely, infusion of ET-1 (0.1 nmol/kg/min) blunted the pressor response to Ang II (0.1 micrograms/kg) but not to MTX (50 micrograms/kg). These doses induced the same increase of DBP in pithed control rats. Similarly, increased plasma renin activity induced by chronic salt depletion (0% NaCl) in pithed rats provoked a shift to the right of the dose-response curves to Ang II and ET-1 but not to MTX. These results suggest an in vivo cross-desensitization between ET-1 and Ang II.
 ...
PMID:Cross-desensitization between angiotensin II and endothelin-1 in the pithed rat. 172 82

The antihypertensive and tissue-protective effects of nitrendipine were studied after long-term treatment of rats with experimental hypertension. Nitrendipine had opposite effects in comparison with vasodilators like hydralazine or minoxidil. Nitrendipine lowered heart weights, plasma atrial natriuretic peptide levels, and plasma renin activity, and was diuretic. Also, in spontaneously hypertensive rats that had been hypertensive for more than half of their life span prior to treatment, nitrendipine still had these effects. Nitrendipine prevented hypertension-induced mortality, even at subantihypertensive doses. Nitrendipine inhibited endothelin-1-induced DNA synthesis in isolated vascular smooth muscle cells as well as atherosclerotic plaque formation in cholesterol-fed rats.
 ...
PMID:Long-term protective effects of nitrendipine in experimental hypertension. 172 94

Although endothelium-derived prostaglandin I2 stimulates renin release, exogenous endothelium-derived relaxing factor (EDRF) can inhibit it. To characterize the role of EDRF as an endogenous regulator of renin release, we inhibited or stimulated its production in rat renal cortical slices in vitro. Renin concentration in the incubation medium was determined by radioimmunoassay for angiotensin I (Ang I) generation. NG-Monomethyl-L-arginine (LNMMA) (10(-4) M), which blocks EDRF formation, significantly enhanced basal renin release from kidney slices by more than 50% in control medium (40.0 +/- 14.3 ng Ang I/hr/mg/30 min; p less than 0.01) or in medium treated with 1.6 x 10(-5) M meclofenamate (50.8 +/- 8.4 ng Ang I; p less than 0.025). Isoproterenol (10(-5) M)-stimulated renin release (40.0 +/- 14.3 ng Ang I; p less than 0.02) was not modified by LNMMA; addition of L-arginine (10(-5) M), the precursor of EDRF, did not change basal but blocked isoproterenol stimulation of renin. Nitroprusside (10(-5) M) completely reversed melittin-stimulated renin release. Endothelin-1, an endothelium-derived vasoconstrictor, inhibits renin release and stimulates EDRF and prostaglandin synthesis. To determine whether any of the renin-inhibiting effect of endothelin-1 was due to its stimulation of EDRF, we compared the effect of endothelin-1 on cortical slices with and without EDRF inhibition. Endothelin-1 (10(-7) M) decreased renin by 36.7 +/- 10.9 ng Ang I (p less than 0.01) compared with controls, and the response was the same after either LNMMA or hemoglobin treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Nonprostanoid endothelium-derived factors inhibit renin release. 173 97

In cultured endothelial cells, endothelin is produced after stimulation with angiotensin II. The effects of angiotensin II and endothelin-1 on vascular sensitivity to norepinephrine were studied in perfused rat mesenteric resistance arteries. Expression of endothelin messenger RNA (mRNA) was determined in endothelial cells obtained from the mesenteric circulation. Perfusion (5 hours) of the arteries with angiotensin II (10(-7) M) potentiated contractions in arteries with endothelium induced by norepinephrine in spontaneously hypertensive rats but not Wistar-Kyoto rats. The potentiation was inhibited by phosphoramidon and an endothelin antibody. Short-term stimulation (1 hour) with angiotensin II did not cause the potentiation. Stimulation with angiotensin I (10(-7) M; 5 hours) caused a potentiation prevented by captopril. In endothelial cells collected from the mesenteric arterial bed of spontaneously hypertensive rats, endothelin-specific mRNA was constitutively expressed, and the level of endothelin transcripts was increased by angiotensin II (10(-7) M). Threshold concentrations of exogenous endothelin-1 potentiated contractions induced by norepinephrine in arteries with and without endothelium of spontaneously hypertensive rats but not Wistar-Kyoto rats. Thus, angiotensin II stimulates the endothelial production of endothelin in situ and therapy potentiates contractions to norepinephrine in mesenteric resistance arteries of spontaneously hypertensive rats. This suggests that vascular endothelin production acts as an amplifier of the pressor effects of the renin-angiotensin system that may play an important role in hypertension.
 ...
PMID:Endothelin stimulated by angiotensin II augments contractility of spontaneously hypertensive rat resistance arteries. 173 46


1 2 3 4 5 6 7 8 9 10 Next >>