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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The antihypertensive mechanism of orally active angiotensin I-converting enzyme inhibitor, SQ 14225 (SQ), in low renin hypertension was investigated. In the SQ-responder with low renin hypertension, the hypotensive effect of SQ was abolished after the inhibition of endogenous prostaglandin (PG) synthesis with indomethacin, while no significant change in blood pressure was found in the SQ-responder with normal renin hypertension. These results suggest that SQ may potentiate the vasodilating PG system, contributing to the antihypertensive mechanism in SQ responders with low renin hypertension.
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PMID:Indomethacin inhibits the antihypertensive effect of captopril, SQ 14225, in low renin hypertension. 701 Jun 81

Antihypertensive effect of an orally active angiotensin I-Converting enzyme inhibitor, SQ 14225 (Captopril) was assessed in 18 hypertensive patients, of whom 13 had essential hypertension, 2 had malignant hypertension, 2 had hypertension associated with chronic renal failure, and 1 had renovascular hypertension. Blood pressure decreased markedly not only in patients with high renin levels but also in those with low renin levels. Nevertheless, the magnitude of blood pressure reduction was correlated with the pre-treatment plasma renin activity (r =-0.64, p less than 0.01 systolic, r =- 0.60, p less than 0.05 diastolic). There was a significant correlation between the fall in mean blood pressure and the decrease in plasma aldosterone concentration 3 weeks after treatment (r = 0.64, p less than 0.05). The serum potassium elevated from 4.2 +/- 0.4 to 4.8 +/-0.9 mEq/L (p less than 0.05), and the change correlated inversely with the reduction of plasma aldosterone concentration (r = 0.71, p less than 0.02), while serum sodium slightly decreased from 140-+/- 2 to 138 +/- 3 mEq/L. There was neither finding of orthostatic hypotension nor escape from the antihypertensive effect. These results indicate that chronic inhibition of angiotensin I-converting enzyme with an orally active compound offers an effective and well-tolerated approach to treatment of hypertension.
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PMID:Antihypertensive effect of the oral angiotensin I-converting enzyme inhibitor in long-term treatment of hypertensive patients. 704 Jul 24

Using ion-exchange chromatography of dialyzed human urine from healthy and hypertensive patients, we detected two peaks of angiotensin I-converting enzyme (ACE) activity on hippuryl-His-Leu eluted at ionic strengths of 0.7 (F1 peak) and 1.25 (F2 peak) mS. These hydrolytic activities decreased gradually in the urine of patients submitted to isradipine treatment, F2 and F1 disappearing after 12 and 24 hours, respectively. By Western blot analysis, the urine fractions corresponding to both peaks from healthy and untreated patients presenting ACE activity and from treated patients (24 hours) without this activity were recognized by an ACE-specific antibody. These results indicated that ACE was present but inhibited in the urine of isradipine-treated patients. In vitro assays with ACE isolated from human urine and guinea pig plasma demonstrated that the enzyme is inhibited by isradipine and other commercially available calcium channel blockers, such as felodipine, nifedipine, and verapamil. A noncompetitive inhibition was observed with all calcium channel blockers studied. In conclusion, these results suggest that besides the primary effect on calcium channels, the more commonly used calcium channel blockers are also ACE inhibitors. The development of efficient calcium channel blockers with higher ACE inhibitory activity could result in interesting bifunctional antihypertensive drugs.
Hypertension 1995 Dec
PMID:Calcium channel blockers as inhibitors of angiotensin I-converting enzyme. 749 85

Chronic hypertension is associated with impaired endothelial function [i.e., reduced synthesis/release of endothelium-derived relaxing factor (EDRF) and increased synthesis/release of endothelium-derived contracting factor (EDCF)] in both animals and humans. Although it is not known whether endothelial dysfunction is the consequence and/or an important pathogenetic cause of hypertension, the goal of effective antihypertensive therapy should include restoration of normal endothelial function as well. Because angiotensin I-converting enzyme (ACE) inhibitors are effectively used in the treatment of hypertension, the aim of the present study was to test whether in vivo treatment of spontaneously hypertensive rats (SHRs) with the ACE inhibitor cilazapril improves endothelial function in the isolated thoracic aorta of SHRs. Treatment of SHRs with cilazapril (10 mg/kg/day orally for 2 weeks) resulted in a significant decrease in blood pressure and normalization of endothelium-dependent relaxation evoked by acetylcholine (ACh) and adenosine diphosphate (ADP). However, cilazapril treatment had no significant effect on endothelium-dependent contractions evoked by 5-hydroxytryptamine (5-HT; serotonin) and prostaglandin F2 alpha (PGF2 alpha). In contrast, in vitro treatment of isolated thoracic aortas with indomethacin (10(-5) M) normalized endothelium-dependent relaxations to ACh and ADP as well as inhibited endothelium-dependent contractions to 5-HT and PGF2 alpha. These results suggest that the ACE inhibitor cilazapril increases the synthesis/release of EDRFs whereas indomethacin prevents the synthesis/release of cyclo-oxygenase-derived EDCFs in the endothelium of rat aorta. The exact mechanism of action of ACE inhibitors on endothelial dysfunction remains to be determined.
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PMID:Effect of cilazapril and indomethacin on endothelial dysfunction in the aortas of spontaneously hypertensive rats. 750 48

We have previously identified a locus on rat chromosome 10 as carrying a major hypertension gene, BP/SP-1. The 100:1 odds support interval for this gene extended over a 35-centimorgan (cM) region of the chromosome that included the angiotensin I-converting enzyme (ACE) locus as demonstrated in a cross between the stroke-prone spontaneously hypertensive rat (SHRSPHD) and the normotensive Wistar-Kyoto (WKY-0HD) rat. Here we report on the further characterization of BP/SP-1, using a congenic strain, WKY-1HD. WKY-1HD animals carry a 6-cM chromosomal fragment genotypically identical with SHRSPHD on chromosome 10, 26 cM away from the ACE locus. Higher blood pressures in the WKY-1HD strain compared with the WKY-0HD strain, as well as absence of linkage of the chromosome 10 region to blood pressure in an F2 (WKY-1HD x SHRSPHD) population suggested the existence of a quantitative trait locus, termed BP/SP-1a, that lies within the SHRSP-congenic region in WKY-1HD. Linkage analysis in the F2 (WKY-0HD x SHRSPHD) cross revealed that BP/SP-1a is linked to basal blood pressure, whereas a second locus on chromosome 10, termed BP/SP-1b, that maps closer to the ACE locus cosegregates predominantly with blood pressure after exposure to excess dietary NaCl. Thus, we hypothesize that the previously reported effect of BP/SP-1 represents a composite phenotype that can be dissected into at least two specific components on the basis of linkage data and congenic experimentation. One of the loci identified, BP/SP-1a, represents the most precisely mapped locus affecting blood pressure that has so far been characterized by random-marker genome screening.
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PMID:Dissection of a quantitative trait locus for genetic hypertension on rat chromosome 10. 756 16

The effect of treatment with two different antihypertensive agents on the function of small arteries from 17 patients with essential hypertension randomly assigned to receive either the angiotensin I-converting enzyme inhibitor cilazapril or the beta-blocker atenolol was investigated. Subcutaneous small arteries obtained from gluteal fat biopsies were studied on a wire myograph before treatment and at 1 and 2 years of treatment. Blood pressure was mildly elevated in both groups of patients (mean, 150/100 mm Hg) and was well controlled throughout the 2 years of treatment (mean, 130/85 mm Hg). We previously reported, in arteries from patients treated with cilazapril, an improvement at 1 year of treatment of the vasoconstrictor effect of endothelin-1, which had been significantly attenuated in the untreated hypertensive patients compared with normotensive subjects. After 2 years of treatment, this normalization of endothelin-1 response was still present in small arteries of patients treated with the angiotensin I-converting enzyme inhibitor, whereas in patients treated with atenolol, responses were still unchanged after 2 years of treatment. Endothelial function was tested by examining the response of norepinephrine-precontracted arteries to acetylcholine. Untreated hypertensive patients exhibited a slightly but significantly blunted vasorelaxation in response to 10 mumol/L acetylcholine compared with normotensive subjects. After 1 and 2 years of effective antihypertensive treatment, cilazapril-treated patients exhibited responses to acetylcholine that were not different from those of normotensive subjects, whereas atenolol-treated patients still had impaired responses.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1995 Apr
PMID:Comparison of effects of angiotensin I-converting enzyme inhibition and beta-blockade for 2 years on function of small arteries from hypertensive patients. 772 19

The determination of the angiotensin I-converting enzyme activity (ACE, kininase II, peptidyldipeptide hydrolase, EC 3.4.15.1) is necessary to control the course and the treatment of sarcoidosis, as well as to monitor the therapeutic use of enzyme inhibitors such as captopril in hypertension or congestive heart failure. Numerous synthetic substrates are known with which to measure the enzyme activity. A discontinuous method using hippuryl-L-histidyl-L-leucine was tested and improved. The cleavage product, hippurate, reacts with cyanuric chloride to give a yellow complex which can be measured at 405 nm using a spectral line photometer. Enzyme activity, kinetic constants and activation energy are dependent on the chloride ion concentration. Optimal test concentrations are 1.1 mol/l potassium chloride and 3.0 mmol/l hippuryl-L-histidyl-L-leucine at pH 8.3. Higher substrate concentrations effect an inhibition of the enzyme reaction. A Michaelis constant of 0.9 mmol/l was found with serum as enzyme source. An activation energy of 57 kJ/mol was obtained from the relation between the logarithm of velocity of enzyme reaction and reciprocal value of absolute temperature. Furthermore, a linear dependence on chloride ion concentration was observed. The histogram of the enzyme activities in sera from 146 healthy volunteers shows a non-gaussian distribution. The reference interval at 25 degrees C is characterized by a median of 24 units/l with the 2.5th and the 97.5th percentiles at 13 units/l and 42 units/l, respectively. The corresponding values at 37 degrees C are 27 units/l and 86 units/l with a median of 48 units/l. No significant sex and age dependence could be found. A potent ACE inhibitor such as captopril leads to a rapid decrease of the enzyme activity within 60 min after oral administration. In the following hours, the enzyme activity slowly increases.
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PMID:Optimized determination of angiotensin I-converting enzyme activity with hippuryl-L-histidyl-L-leucine as substrate. 795 11

1. Stroke-prone spontaneously hypertensive rats (SHRSP) were fed a diet with fish meal as the protein source (fish diet) during the progressive stage of hypertension, and its effects on the activity of angiotensin I-converting enzyme (ACE) in serum and vascular tissues and on the aortic elastin content were studied. The effects of the antihypertensive drugs captopril and hydralazine were also studied. 2. Stroke-prone spontaneously hypertensive rats fed the fish diet showed a distinctly lower level (P < 0.05) of serum ACE activity than the control group fed a commercial stock chow. 3. ACE activity was enhanced in the SHRSP which was administered with captopril. 4. Serum ACE activity was similar in the SHRSP receiving the hydralazine treatment and the control group. 5. The thoracic aorta ACE activity was lowered more (P < 0.05) in the fish diet group and the captopril-treated group than in the control group. In the hydralazine-treated group however, the activity was similar to the control group. 6. The ratio of aorta weight to bodyweight was significantly lower (P < 0.05) in the fish diet group and the captopril-treated group than in the control group, but there was no difference in the hydralazine group. Higher levels of aortic elastin were observed in the drug-treated groups (P < 0.05). 7. No differences were seen between the fish diet and captopril-treated groups by electron-microscopy. 8. The results suggest that suppression of hypertrophy and ameliorations of reduction in elasticity of the vascular wall in the SHRSP fed a fish diet were due to inhibition of vascular tissue ACE activity.
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PMID:The vascular tissue angiotensin I-converting enzyme activity and aortic elastin content in stroke-prone spontaneously hypertensive rats fed fish diet. 798 75

In order to clarify the therapeutic policy for hypertension in the elderly, we mailed a questionnaire to 147 specialists in Japan and received 123 replies. The upper age limit for antihypertensive treatment was considered to be 80-85 years old by about 50% of the specialists, but the other 50% did not consider an upper age limit. The range of the systolic blood pressure (BP) for which drug treatment was indicated in those without cardiovascular complications was considered to be increased with age, being 160 mmHg and higher in those aged 60-69, 160-170 mmHg and higher in those aged 70-79, and 170-180 mmHg and higher in those aged 80-89, while the level of diastolic BP requiring treatment was considered to be 90-95 mmHg and higher in all age ranges. The goal of BP control was considered to be less than 150/90 mmHg in those aged 60-69, and less than 160/90 mmHg in those aged 70-79 by the majority of the specialists, and to be higher in those aged 80-90, i.e. less than 170-180/95-100 mmHg by more than 20% of the specialists. As the initial selection of antihypertensive regimen, calcium antagonists followed by angiotensin I-converting enzyme inhibitors (ACEI) were selected by the majority, while diuretics, beta-blockers and alpha 1 blockers were chosen by the minority.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Therapeutic policy for elderly hypertensives in Japan--a questionnaire survey of specialists]. 807 11

The angiotensin I-converting enzyme (ACE) gene is found on the locus that has been linked to high blood pressure after sodium loading in rats, so in the present study we investigated the role of vascular ACE for the pathophysiology of hypertension in the corresponding parental strains, Wistar-Kyoto (WKY) rats and stroke-prone spontaneously hypertensive rats (SHRSP), in basal conditions at different ages and after sodium loading. Blood pressure was already significantly enhanced in SHRSP from 4 weeks of age, and sodium loading induced an additional increase only in the hypertensive strain. In the aorta, basal ACE gene expression, analyzed by quantitative polymerase chain reaction, and ACE activity were similar in both strains, whereas mRNA levels were elevated in SHRSP after salt compared with WKY rats and correlated with an increase in enzymatic activity. In mesenteric arteries, ACE mRNA levels were significantly enhanced in SHRSP at all ages, although ACE activity was not different between the strains. These results were not modified after sodium loading. These data demonstrate that the level of ACE activity in plasma and vascular tissue can be controlled in a different manner within a rat strain and that in contrast to the soluble form, the membrane-bound ACE may be the one responsible for determining the vasoactive effects of angiotensin II. In addition, ACE undergoes a different regulation in vascular tissues of SHRSP compared with WKY rats, which might be involved in the regulation of blood pressure in these animals.
Hypertension 1994 Sep
PMID:Differential regulation of vascular angiotensin I-converting enzyme in hypertension. 808 33


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