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P Corvol

Publications and source records attributed to P Corvol.

At least 19 recordsLinked to original sources
PubMed1992

Functional study of the germinal angiotensin I-converting enzyme promoter.

Polymerase chain amplification experiments indicate that the germinal specific promoter of the angiotensin I-converting enzyme (ACE) is completely extinguished in somatic tissues. Despite this very strict specificity of expression, the germinal ACE promoter is active in transient transfection experiments in two somatic cell lines and one cell line of germinal origin. The analysis of the promoter shows the existence two regulatory elements within the first 350 bp: a proximal positive element and a distal negative element.

Animals↗
PubMed1992

The two homologous domains of human angiotensin I-converting enzyme interact differently with competitive inhibitors.

The endothelial angiotensin I-converting enzyme (ACE; EC 3.4.15.1) has recently been shown to contain two large homologous domains (called here the N and C domains), each being a zinc-dependent dipeptidyl carboxypeptidase. To further characterize the two active sites of ACE, we have investigated their interaction with four competitive ACE inhibitors, which are all potent antihypertensive drugs. The binding of [3H] trandolaprilat to the two active sites was examined using the wild-type ACE and four ACE mutants each containing only one intact domain, the other domain being either deleted or inactivated by point mutation of the zinc-coordinating histidines. In contrast with all the previous studies, which suggested the presence of a single high affinity inhibitor binding site in ACE, the present study shows that both the N and C domains of ACE contain a high affinity inhibitor binding site (KD = 3 and 1 X 10(-10) M, respectively, at pH 7.5, 4 degrees C, and 100 mM NaCl). Chloride stabilizes the enzyme-inhibitor complex for each domain primarily by slowing its dissociation rate, as the k-1 values of the N and C domains are markedly decreased (about 30- and 1100-fold, respectively) by 300 mM NaCl. At high chloride concentrations, the chloride effect is much greater for the C domain than for the N domain resulting in a higher affinity of this inhibitor for the C domain. In addition, the inhibitory potency of captopril (C), enalaprilat (E), and lisinopril (L) for each domain was assayed by hydrolysis of Hip-His-Leu. Their Ki values for the two domains are all within the nanomolar range, indicating that they are all highly potent inhibitors for both domains. However, their relative potencies are different for the C domain (L greater than E greater than C) and the N domain (C greater than E greater than L). The different inhibitor binding properties of the two domains observed in the present study provide strong evidence for the presence of structural differences between the two active sites of ACE.

Angiotensin I↗
PubMed1992

Hypertension in Dahl salt-sensitive rats: biochemical and immunohistochemical studies.

1. The renin-angiotensin and kinin-kallikrein systems of Dahl salt-sensitive and salt-resistant rats fed diets with different salt contents were analysed using biochemical and immunocytochemical techniques. 2. Blood pressure increased by 45% in salt-sensitive rats only, after 4 weeks on a high-salt diet. The plasma renin activity and plasma angiotensin II concentration remained at the same levels in salt-sensitive rats on the high-salt diet as on the normal salt diet, whereas the plasma renin activity and plasma angiotensin II concentration of salt-resistant rats fed the high-salt diet were lower. The plasma renin activity and the plasma angiotensin II concentration were elevated in both salt-resistant and salt-sensitive rats fed the salt-deficient diet but were much more elevated in salt-resistant than in salt-sensitive rats. 3. The kidney immunocytochemical data paralleled the data on plasma parameters. Salt-sensitive rats had fewer renin positive juxtaglomerular apparatuses than salt-resistant rats on the normal diet, and the increase on the sodium-deficient diet was also smaller in salt-sensitive rats. Salt-sensitive rats fed the high-salt diet and the standard diet had almost no angiotensin II immunoreactivity compared with the salt-resistant rats on the same diets. 4. The total renal kallikrein content of salt-sensitive rats was lower than that of salt-resistant rats on all three diets, as was the amount of kallikrein excreted in the urine on the standard and the high-salt diets. The differences resulted from a reduction in active kallikrein. The increase in kallikrein in salt-sensitive and salt-resistant rats on the salt-deficient diet was not significantly different. 5. There were similar changes in immunopositive kallikrein in the kidneys of salt-sensitive and salt-resistant rats with diet, with a large increase in kallikrein biosynthesis on the low-salt diet. The plasma concentration of high-molecular-mass kininogen was not significantly different in salt-sensitive and salt-resistant rats, but there was a significant increase in T-kininogen in salt-sensitive rats fed the high-salt diet. 6. In conclusion, the absence of decreases in the plasma renin activity and the plasma angiotensin II concentration in salt-sensitive rats fed the high-salt diet might partially explain the increase in blood pressure.

Angiotensin II↗
PubMed1992

The angiotensin I-converting enzyme (kininase II): molecular organization and regulation of its expression in humans.

Protein sequencing and molecular cloning of human endothelial angiotensin I-converting enzyme (ACE; kininase II), have led to a description of the structure of the enzyme and to several questions concerning the intracellular maturation of ACE and the mechanisms of enzyme action. With the help of recombinant ACE expression in mammalian cells and site-directed mutagenesis, a model for the maturation of ACE in endothelial cells has been proposed. This model comprises transmembrane anchoring of the membrane-bound ACE near its carboxyterminal extremity, and post-translational cleavage of the anchor in the secreted form. The endothelial ACE displays a high degree of internal homology between two large peptidic domains that each bears a consensus sequence for zinc binding and therefore a putative active site. The testicular ACE, however, encoded from the same gene by a shorter mRNA, contains only the carboxyterminal half of endothelial ACE and therefore a single active site. Expression of ACE mutants with only one intact homologous domain, however, indicates that in endothelial ACE both domains are enzymatically active. Further characterization of these two active sites of endothelial ACE is in progress. In humans, population studies have indicated that the large interindividual variability in plasma ACE levels is partly genetically determined and under the influence of a major gene effect. This was later confirmed and extended by the observation of an insertion-deletion polymorphism of the ACE gene that is associated with the level of ACE in plasma. The clinical implications of these observations are discussed.

Cloning, Molecular↗
PubMed1992

Effects of the selective neutral endopeptidase inhibitor, retrothiorphan, on renal function and blood pressure in conscious normotensive Wistar and hypertensive DOCA-salt rats.

Atrial natriuretic peptide (ANP) is degraded by neutral endopeptidase (NEP) mainly in the proximal tubule of the kidneys. We studied the effects of retrothiorphan, a potent and highly specific NEP inhibitor on renal function and blood pressure (BP). A 25-mg/kg bolus injection (group bolus), or bolus injection plus infusion 25 mg/kg + 25 mg/kg/h (group infusion), was given to conscious normotensive Wistar and hypertensive DOCA-salt rats. Bolus and infusion produced increases in diuresis (110 +/- 15 vs. 103 +/- 15 vs. 42 +/- 9 microliters/min) and natriuresis (10.6 +/- 3.0 vs. 7.0 +/- 1.0 vs. 5.4 +/- 1.0 mumol/min) in normotensive rats, with a maximum change at 30 min. Change in kaliuresis was not significant. These renal effects were associated with nonsignificant increases in urinary cyclic GMP and ANP. Arterial pressure and heart rate (HR) were not affected. Bolus or infusion of retrothiorphan also induced increases in diuresis (92 +/- 16 vs. 124 +/- 13 vs. 38 +/- 6 microliters/min) and natriuresis (10.3 +/- 2.0 vs. 12.5 +/- 1.0 vs. 5.0 +/- 1.0 mumol/min) in DOCA-salt hypertensive rats, with a maximum change at 30 min. The changes in diuresis and natriuresis induced by retrothiorphan were correlated with a significant increase in urinary cyclic GMP excretion (r = 0.89, p < 0.001 and r = 0.91, p < 0.001). Urinary ANP did not change in controls but significantly increased in the treated rats; urinary immunoreactive bradykinin (BK) also tended to increase. Plasma ANP and hematocrit did not change after retrothiorphan, but plasma cyclic GMP increased significantly after infusion. Only infusion caused a decrease in arterial pressure in DOCA-salt rats (-20 mm Hg at 120 min). Renal clearance studies in DOCA-salt rats showed that retrothiorphan has a transient effect on renal hemodynamics, with increases in glomerular filtration and renal blood flow (RBF) and a decrease in renal vascular resistance (RVR). Its renal action was also tubular, with an increase in fractional sodium excretion. We also compared the effects of retrothiorphan in normotensive Brown-Norway kininogen-deficient rats (BN-Kat) and DOCA-salt hypertensive kininogen-deficient rats. The NEP inhibitor induced increases in diuresis and natriuresis in both groups, with increased urinary cyclic GMP. Urinary immunoreactive BK did not change significantly in normotensive or DOCA-salt hypertensive kininogen-deficient rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1992

Investigation of the biochemical effects of renin inhibition in normal volunteers treated by an ACE inhibitor.

1. In order to investigate accurately the biochemical effects of renin inhibition in man, we have developed a sensitive assay to measure angiotensin I (1-10) decapeptide. 2. Angiotensins were extracted from plasma by adsorption to phenylsilylsilica, and angiotensin I (Ang I) was quantified by radioimmunoassay. The detection limit was 0.77 fmol ml-1, and the extraction recovery of [125I]-Ang I added to albumin buffer was 83% at the inflection point (10 fmol ml-1) of the standard curve. The overall recovery was 98.5 +/- 3.5%. The intra- and inter-assay reproducibility was 10.4% and 9.7% respectively. Cross-reactivity of the antiserum used was low (less than 0.3%) with all angiotensin peptides tested except Ang (2-10) nonapeptide. 3. A human pharmacological model was subsequently used to assess in vivo the biochemical effects of the renin inhibitor CGP 38560A. Six healthy volunteers received 20 mg lisinopril, a long-acting ACE-inhibitor. During the following 24 h, the renin-angiotensin system was reset with typically elevated active plasma renin and Ang I, at respectively 275 and 429% of basal values. 4. In a randomized three-way cross-over protocol, the six volunteers received a 30 min infusion of the renin inhibitor CGP 38560A (125 or 250 micrograms kg-1) or 5% glucose. The fall in plasma Ang I was 92% and 97.5% after the lowest and highest dose of the renin inhibitor, respectively. A concomitant increase in active plasma renin was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Phorbol ester inhibits erythropoietin production in human hepatoma cells (Hep G2).

Using the human hepatoma cell line Hep G2, we have studied a possible role of protein kinase C (PKC) activity for regulation of erythropoietin (EPO) production. During a 72-h incubation, EPO production by the cells was stimulated sevenfold by exposure to low oxygen tension (1%) and threefold by exposure to cobaltous chloride (100 microM). The phorbol ester phorbol 12-myristate-13 acetate (PMA) led to a concentration-dependent inhibition of basal and stimulated EPO formation (ED50 10 nM). This decrease of EPO production, which was apparent already after 1 h of incubation with PMA, reached its maximal effect after 24 h and held on for 72 h. It was paralleled by an inhibition of the increase of EPO mRNA levels in response to stimulation. A 24-h preincubation of the cells with PMA (100 nM) virtually blunted the effect of hypoxia on EPO formation. Recovery of EPO synthesis after removal of PMA took 48-72 h. The effect of PMA on EPO production was mimicked by phorbol 12,13-dibutyrate (ED50 1 microM) but not by 4 alpha-phorbol 12,13-didecanoate. The synthetic diacylglycerol analogues oleolyl-acetylglycerol and dioctanoylglycerol (2-200 microM) also had no effect on either basal or stimulated EPO production. Treatment with PMA caused a translocation of the alpha-isoenzyme of PKC from the cytosol to the membrane after 1 h and a disappearance of the membrane-bound form after 24 h of incubation. Staurosporine and 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine, two structurally different inhibitors of PKC activity, inhibited basal and stimulated EPO production with ED50 values of 9 nM and 50 microM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Evidence, from combined segregation and linkage analysis, that a variant of the angiotensin I-converting enzyme (ACE) gene controls plasma ACE levels.

The hypothesis of a genetic control of plasma angiotensin I-converting enzyme (ACE) level has been suggested both by segregation analysis and by the identification of an insertion/deletion (I/D) polymorphism of the ACE gene, a polymorphism contributing much to the variability of ACE level. To elucidate whether the I/D polymorphism was directly involved in the genetic regulation, plasma ACE activity and genotype for the I/D polymorphism were both measured in a sample of 98 healthy nuclear families. The pattern of familial correlations of ACE level was compatible with a zero correlation between spouses and equal parent-offspring and sib-sib correlations (.24 +/- .04). A segregation analysis indicated that this familial resemblance could be entirely explained by the transmission of a codominant major gene. The I/D polymorphism was associated with marked differences of ACE levels, although these differences were less pronounced than those observed in the segregation analysis. After adjustment for the polymorphism effects, the residual heritability (.280 +/- .096) was significant. Finally, a combined segregation and linkage analysis provided evidence that the major-gene effect was due to a variant of the ACE gene, in strong linkage disequilibrium with the I/D polymorphism. The marker allele I appeared always associated with the major-gene allele s characterized by lower ACE levels. The frequency of allele I was .431 +/- .025, and that of major allele s was .557 +/- .041. The major gene had codominant effects equal to 1.3 residual SDs and accounted for 44% of the total variability of ACE level, as compared with 28% for the I/D polymorphism.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1979

Physicochemical properties of non-activated and activated renin from human amniotic fluid.

The main physicochemical and enzymic properties of non-activated and activated human amniotic renin (EC 3.4.99.19) were studied in order to clarify the relationships between the two enzymes. Human amniotic renin was activated by dialysis against acidic buffer (pH 3.3), direct acidification or trypsin treatment. All procedures produced similar activation. The physicochemical characteristics of non-activated and activated renin were compared to those of human renal renin. Non-activated renin had a molecular weight of 45,500. A similar molecular weight was obtained by gel eluate activation and by acid treatment of renin prior to gel filtration. Similar isoelectric points were also found for non-activated and activated renin. One major renin peak focused at pH 6.6, whereas no similar renin peak was detected in extracts from normal human kidney. In addition, non-activated and activated renin forms were found to have the same optimal pH, the same Km and the same inhibiting pepstatin concentrations.

Amniotic Fluid↗
PubMed1979

[Phaeochromocytoma: localisation by computerised scanner tomography. 5 cases (author's transl)].

In five patients with a phaeochromocytoma, axial computerised scanner tomography made it possible to localise the tumour without ambiguity, even when intravenous urography had been interpreted as normal. Although all the tumours diagnosed were relatively large (between 3 and 9 cm), this is nevertheless a non-invasive examination, free of danger and worthy of consideration in the preoperative assessment of a case of phaeochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1979

Multiple forms of human renin. Purification and characterization.

Human renin was purified from a juxtaglomerular cell tumor with a high renin content, 24.2 Goldblatt units/mg of protein. The purification procedure comprised three steps: gel filtration, DEAE-cellulose chromatography, and preparative isoelectric focusing. Five forms of renin amounting to 5.3 mg of enzyme were obtained with isoelectric points of 4.95, 5.10, 5.35, 5.55, and 5.70. They were all glycoproteins. The three major fractions had very similar specific activities, 868, 860, and 809 Goldblatt units/mg of protein. These fractions produced a single band on analytical isoelectric focusing and a single arc on immunoelectrophoresis. On polyacrylamide gel electrophoresis at pH 7.8, each fraction consisted of two renin bands with the same molecular weight, but different net charges. The molecular weight determined by gel filtration and Fergusson plot analysis on polyacrylamide gel was 38,000 to 42,000. The optimum pH determined on N-acetyltetradecapeptide substrate was 6.5, and the Km was 6.8 x 10(-6) M. These parameters were identical with those for standard human kidney renin. Antibodies raised against tumor renin completely inhibited the activity of both tumor and standard renin. Under dissociating conditions (sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel electrophoresis in the presence of 6 M urea), part of the purified enzyme dissociated into two smaller fragments (Mr = 20,000 and 25,000) containing renin activity.

Humans↗
PubMed1979

[Plasma renin and noradrenalin levels during hypotensive therapy using acebutolol (author's transl)].

The effects of acebutolol (800 mg per day for three days) on pulse rate, blood pressure, plasma noradrenaline and plasma renin activity were measured in nine patients with essential hypertension, at rest in a horizontal position, after five minutes standing upright and after walking for one hour. Acebutolol reduced pulse rate, blood pressure and plasma renin activity in all three positions. Treatment has no influence on plasma noradrenaline in a horizontal position, but significantly reduced its orthostatic stimulation. The inhibition of noradrenergic response to an orthosatic position is compatible with a central or presynaptic effect of acebutolol. This effect would not appear to be essential to its antihypertensive action since acebutolol reduced blood pressure but not plasma noradrenaline in a horizontal position. Blood pressure response to treatment was positively correlated to initial values of plasma renin activity measured after walking for one hour and plasma noradrenaline measured after five minutes in an orthostatic position. On the basis of this correlation, measurement of these two hormonal indices is of predictive value, within the limits of a short period of treatment with acebutolol and strictly defined hospital conditions.

Acebutolol↗
PubMed1979

Abnormal regulation of antidiuretic hormone in idiopathic edema.

Idiopathic edema is characterized by impaired water excretion, particularly in the upright posture. Indirect evidence has shown that antidiuretic hormone is involved in this disease. For this reason, we measured urinary arginine vasopressin by radioimmunoassay before and during water loading (15 ml/kg) in 10 normal women and in 10 subjects with idiopathic edema in both the supine and upright postures. Daily sodium intake was 100 meq. Renin and aldosterone were concomitantly investigated, and abnormally high values were observed both in the recumbent and upright postures. Basal values for urinary arginine vasopressin were identical in control subjects and in patients with idiopathic edema. The water load significantly reduced urinary arginine vasopressin in normal women in both positions, but in those with idiopathic edema only in the supine position. In those with idiopathic edema, assumption of the upright posture was accompanied by a transient decrease in glomerular filtration, a major decrease in osmolar clearance and no decrease in urinary arginine vasopressin after water loading. Significant correlations were established between urinary arginine vasopressin and osmolar or volemic parameters in normal women, but these correlations were not found in those with idiopathic edema in either position. Arginine vasopressin regulation was abnormal in idiopathic edema, and this hormone was believed to play a part in the pathogenesis of this disease.

Adult↗
PubMed1979

Comparative effects of canrenoate-K and prorenoate-K upon aldosterone biosynthesis in perifused frog interrenal glands.

To investigate the possible direct effect of two aldosterone antagonists (Canrenoate-K and Prorenoate-K) upon mineralocorticoid biosynthesis a perifusion system technique has been developed. Frog interrenal tissue was selected for its ability to secrete huge amounts of aldosterone (twice as much as corticosterone in resting conditions). Throughout the experiment, secretion of aldosterone was measured every ten minutes by means of a sensitive and highly specific radioimmunoassay method. Increasing concentrations of both Canrenoate-K and Prorenoate-K (ranging from 10(-4)M to 10(-3)M) caused a dose-related inhibition of aldosterone output. At a dose of 3.16 x 10(-4)M, Prorenoate-K appeared to be somewhat more potent (57.8% inhibition) than Canrenoate-K (47.8% inhibition). Infusion of both Canrenoate-K and Prorenoate-K at a dose of 5 x 10(-4)M during 1 or 2 hours induced a similar sharp decrease in mineralocorticoid secretion. Thus, it appears that Canrenoate-K and Prorenoate-K beside their well known effects at renal tubular receptor sites do also inhibit aldosterone biosynthesis. These results indicate that in vivo administration of aldosterone antagonists may first involve a transient decrease in aldosterone secretion. Furthermore, they suggest that mineralocorticoid biosynthesis might be regulated by a short loop feedback mechanism.

Adrenal Glands↗