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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Seven patients with essential hypertension and seven patients with hypertension associated with renal artery stenosis received captopril (SQ 14225), an inhibitor of angiotensin I converting enzyme. There was a significant reduction in mean blood pressure, from 176/113 +/- 4/3 mm Hg during the control period to 140/90 +/- 5/3 mm Hg during captopril administration. Five patients received captopril alone and nine patients needed hydrochlorothiazide in addition to control their blood pressure. Captopril produced a significant increase in peripheral plasma renin activity. When measured 12 hours after the administration of captopril the angiotensin I converting enzyme activity was found to be similar to that during the control period even though the blood pressure was at or near normal. These findings indicate that although captopril is an effective antihypertensive agent, its action does not depend only on inhibition of plasma angiotensin I converting enzyme activity.
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PMID:Effect of captopril (SQ 14225) on blood pressure, plasma renin activity and angiotensin I converting enzyme activity. 22 56

An attenuation of adrenergic activity during the inhibition of endogenous angiotensin II formation was evaluated by determining plasma norepinephrine concentration after a single oral administration of captopril compared to that after nifedipine in essential hypertension. Captopril produced a fall in mean arterial pressure (-24 +/- 2 mmHg, p less than 0.01) which magnitude was the same as that gained by nifedipine (-22 +/- 3 mmHg, p less than 0.01). Reflex tachycardia due to hypotension was produced (+13 +/- 1 beats/min, p less than 0.01) after nifedipine but not after captopril (-1 +/- 2 beats/min, p greater than 0.05). Although the enhancement of plasma renin activity induced by captopril (+1.54 +/- 0.56 ng/ml/hr, p less than 0.05) was similar (p greater than 0.05) to that by nifedipine (+1.44 +/- 0.47 ng/ml/hr, p less than 0.05), plasma norepinephrine concentration increased less (p less than 0.01) after captopril (+100 +/- 23 ng/ml, p less than 0.05) than after nifedipine (+283 +/- 51 ng/ml, p less than 0.05). Thus, the diminished adrenergic activity is a likely candidate for the abolished reflex tachycardia after the inhibition of angiotensin I converting enzyme activity by captopril in essential hypertension.
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PMID:Captopril attenuates reflex adrenergic response in essential hypertension. 199 80

Patients with essential hypertension were studied to clarify the role of the kallikrein-kinin system in the hypotensive actions of angiotensin I converting enzyme inhibitors. Captopril, alacepril, ramipril, and altiopril administered in single doses rapidly decreased blood pressure and plasma angiotensin II levels, and increased plasma and urinary kinins as well as plasma renin activity. Following administration of captopril for 14 days, similar effects were observed. Urine volume and urinary sodium excretion were augmented after acute and chronic administration of captopril. The patients who received ramipril and altiopril were divided into renin subgroups. In the normal-renin group, the change in blood pressure was accompanied by an increase in plasma kinin level and a decrease in plasma angiotensin II level. However, in the low-renin group, although these drugs reduced blood pressure and increased plasma kinin, no significant change was observed in plasma angiotensin II levels. These findings suggest that (a) in patients with normal renin activity, the hypotensive effect of converting enzyme inhibitors might be caused by an increase in plasma kinin and a decrease in plasma angiotensin II, but in the low-renin group, the increase in plasma kinin levels may be more important; and (b) the augmentation of urine volume and urinary sodium excretion may also be related to the hypotensive effects of the converting enzyme inhibitors during long-term administration.
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PMID:Role of kallikrein-kinin system in the hypotensive mechanisms of converting enzyme inhibitors in essential hypertension. 247 7

The author reviews contemporary views on the pathogenetic participation of selected humoral factors (of the renin-angiotensin-aldosterone system, natriuretic hormone and atrial natriuretic factor) in the development of arterial hypertension in humans. Hypertension may be due to absolute or relative excess of factors with a pressor and antinatriuretic action or to deficiency of depressor and natriuretic substances. In essential hypertension and the majority of other types of hypertension the position is more complicated. Humoral substances are there involved in a complex way in dynamic interaction with other genetic, nervous, cardiovascular and other mechanisms. Investigation of humoral substances has helped to elucidate the causes of endocrine-hypertension, to expand our knowledge on the multifactorial genesis of essential hypertension, to differentiate its subtypes, and it led also practical therapeutic outcome such as the use of inhibitors of the angiotensin I converting enzyme or spirolactone.
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PMID:[Humoral mechanisms in the pathogenesis of arterial hypertension with emphasis on the renin-angiotensin-aldosterone system and natriuretic substances]. 252 99

In order to investigate the role of plasma angiotensin I (pAI) converting enzyme on the activity of the renin-angiotensin system, we measured plasma renin activity (PRA), plasma angiotensin II (pAII), and plasma angiotensin I converting enzyme (pACE) activity in fourteen patients with essential hypertension before and after two hours of ambulation combined with intravenous furosemide administration. Significant increases were observed in the values of PRA (p less than 0.005), pAII (p less than 0.005) and ACE activity (p less than 0.05) after ambulation. The ratios of log pAII/log PRA were increased significantly after ambulation (p less than 0.005), and a significantly positive correlation was observed between log pAII/log PRA and ACE activity (p less than 0.01). These results suggested that not only PRA but also ACE activity contributed to the activity of renin-angiotensin system through the generation of AII.
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PMID:The role of plasma angiotensin I converting enzyme in regulation of renin-angiotensin system activity in patients with essential hypertension. 283 30

The activity of the angiotensin I converting enzyme was measured in 55 patients with untreated essential hypertension, 11 patients with untreated renovascular hypertension, five patients with untreated primary aldosteronism, and 23 normotensive subjects. Converting enzyme activity was significantly higher (p less than 0.025 or less) in essential hypertension (28 +/- 1 units/ml) and renovascular hypertension (28.5 +/- 3 units/ml) when compared with the activity in the normotensive subjects (21 +/- 1.5 units/ml). Seventeen (31 percent) of the patients with essential hypertension and three (27 percent) patients with renovascular hypertension had an elevated converting enzyme activity above the mean +2 standard deviations value of the normotensive subjects (32.8 units/ml), ranging from 33 to 55.8 units/ml. Converting enzyme activity was similar in black and white patients and in male and female patients, but it tended to decrease with increasing age in both the hypertensive and the normotensive subjects. In the untreated patients with essential hypertension (n = 55), converting enzyme activity was inversely related to mean arterial pressure and age (r = -0.34, p less than 0.01) and positively related to plasma renin activity (r = 0.31, p less than 0.05). Converting enzyme activity was always decreased during captopril therapy, and it was not affected by beta blockers, but it was increased by diuretics. These findings indicate that converting enzyme activity is elevated in patients with essential and renovascular hypertension.
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PMID:Angiotensin I converting enzyme activity in hypertension. Relationship to blood pressure, renin-sodium profiles, and antihypertensive therapy. 286 56

Hyperuricaemia carries with it a high risk of tophi development affecting connective tissue in kidney, skin and joints, its overt clinical expression being gout. Diuretics, which are invariably prescribed in congestive heart failure and widely used for the treatment of essential hypertension, may cause hyperuricaemia and predispose to gout by inducing renal retention of urate. The angiotensin I converting enzyme inhibitors captopril and enalapril have been found to augment renal urate excretion both in normal volunteers and in hypertensive patients. Current evidence appears to indicate that the uricosuric effect of captopril and enalapril could be due to the rises in renin and angiotensin I these drugs elicit by angiotensin I converting enzyme inhibition, and/or to pharmacological actions not related, at least directly, to the renin-angiotensin-aldosterone system. Serum urate levels have been significantly reduced by monotherapy with captopril in hypertensive patients suffering from hyperuricaemia. Diuretic-induced hyperuricaemia in hypertensive patients can be prevented or counteracted by the administration of captopril and enalapril. Available clinical data support the argument that captopril and enalapril should be used as first choice drugs for the treatment of hyperuricaemic hypertensive patients. When diuretic-induced hyperuricaemia develops in patients suffering from congestive heart failure, captopril or enalapril should be added to the therapeutic regime in doses capable of countering the shift in plasma urate concentration, provided the clinical condition of the patients permits such additional pharmacological treatment. Therapy with captopril and enalapril should preferably be instituted in a gradual manner, especially in patients with hyperuricaemia, in order to prevent the precipitation of urate in the kidney and in the urinary tract.
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PMID:Angiotensin I converting enzyme inhibitors and the renal excretion of urate. 315 8

Increased total peripheral resistance is the cardinal haemodynamic disorder in essential hypertension. This could be secondary to alterations in the mechanical properties of vascular smooth muscle. Adequate study has not been made of the tension-velocity (T-V) relationship in hypertensive resistance arterial smooth muscle. Increased narrowing in such arteries would result in increased resistance. The objectives of this investigation were to determine whether there is (i) increased narrowing capacity (-delta C/C omicron, where C stands for arterial internal circumference and C omicron is the optimal arterial internal circumference for maximum tension development); (ii) an increased maximum velocity of isobaric narrowing (Vmax) measured in C omicron per second; (iii) an increased wall thickness (h); and (iv) an increased active stress development (Tmax) in the spontaneously hypertensive rat (SHR; n = 5) compared with the normotensive Wistar Kyoto (WKY; n = 5) and MK-421 (an angiotensin I converting enzyme inhibitor) treated spontaneously hypertensive rat (MK-421 trt. SHR; n = 5) mesenteric resistance (diameter, less than 300 micron) arteries. Analysis of the data for arteries constricting isobarically against a range of pressures revealed that (a) the SHR -deltaC/C omicron values at pressures ranging from 20 to 120 mmHg (1 mmHg = 133.322 Pa) showed significantly increased narrowing compared with the MK-421 trt. SHR and WKY -deltaC/C omicron values in this same pressure range (p less than 0.01), and (b) the SHR derived Vmax of 0.83 +/- 0.08 C omicron/s was significantly faster than either the MK-421 trt.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tension-velocity relationships in hypertensive mesenteric resistance arteries. 404 6

We studied the possible interplay between plasma bradykinin (P-BK) and the renin-angiotensin axis in essential hypertension, the effect of catecholamine on P-BK by standing and norepinephrine (NE) infusion, and the possible role of bradykinin in the hypotensive mechanism of angiotensin I converting enzyme inhibitor (captopril) in renin-independent essential hypertension. Plasma bradykinin was measured by sensitive radioimmunoassay in 44 hypertensive patients and compared with that of 24 normotensive subjects. P-BK was not significantly reduced in hypertensive patients, and when subjects were divided by age range, the P-BK was reduced by aging in normotensive subjects but not in hypertensive patients, and the elder (60 approximately 80 yr) age normotensive group showed significantly (p less than 0.05) lower P-BK compared with the elder hypertensive group. 28 essential hypertensive patients (EHT) who were classified as WHO stageI (n=15) and WHO stageII (n=13) were given 80 mg of furosemide orally and kept upright for 4 hours. Plasma renin activity (PRA), P-BK, plasma aldosterone (P-Ald) and serum angiotensin converting enzyme activity (ACEA) were measured before and after furosemide administration. Twelve normotensive subjects served as controls. PRA, P-Ald and ACEA showed a significant increase (p less than 0.05) in all groups in response to furosemide. In normotensives, basal P-BK was 11.1 +/- 1.3 pg/ml which increased to 15.6 +/- 1.8 pg/ml (p less than 0.02) after furosemide. These changes of P-BK were in parallel with PRA, P-Ald and ACEA. In the WHO stageI EHT group, baseline P-BK was 9.7 +/- 1.3 pg/ml which increased to 15.6 +/- 1.8 pg/ml (p less than 0.02) and PRA, P-Ald and ACEA showed a similar increase as in normotensives. In the WHO stageII EHT patients, however, P-BK showed only a slight increase from 9.8 +/- 1.0 pg/ml to 12.0 +/- 1.1 pg/ml after furosemide. These changes were smaller either than normotensives or the WHO stageI EHT group. There was a slight but significant correlation between PRA and P-BK in normotensives and in the WHO stageI EHT. There was no correlation between PRA and P-BK in the WHO stageII EHT. The present results do not support the view that there may be a direct linkage between the kallikrein kinin system and the renin angiotensin axis mediated by kininase II or angiotensin converting enzyme in human peripheral blood.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[The effect of alterations of the renin-angiotensin system and the sympathetic nervous system on plasma bradykinin concentration in patients with essential hypertension]. 609 86

In order to investigate the possible role of bradykinin in the hypotensive mechanism of angiotensin I converting enzyme inhibitor (Captopril) in renin-independent essential hypertension (EHT), we studied the effects of the single administration of 100 mg captopril on plasma bradykinin levels by sensitive radioimmunoassay in 21 EHT, who showed agonistic responses to 1Sar, 8Ile-angiotensin II (A IIA). Fourteen of the patients were low renin and 7 were normal renin EHT. There was no correlation between the baseline plasma renin activity (PRA) and the fall in mean blood pressure (MBP) following captopril administration. When the patients were analyzed according to MBP response, the responders (R) showed a significantly greater bradykinin increment (delta BK, +64%) (p less than 0.05), whereas the nonresponders (NR) did not show such an increase. There was a positive correlation between delta BK and the MBP reduction after captopril in the R group (r = 0.623, p less than 0.05). Plasma aldosterone (PA) decreased profoundly in the R group (-36% from baseline, p less than 0.05). Pretreatment ACE activity was significantly higher in the R group than in the NR group (p less than 0.05). Pressor response to A IIA showed a significantly (p less than 0.05) greater response after captopril administration in the R group. There were no significant differences in blood concentration of captopril between the R and NR groups. The present results suggest that bradykinin may be involved in the hypotensive action of captopril in the EHT subgroup, where the renin-angiotensin system appears to play an inert role for the elevation of blood pressure.
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PMID:[Antihypertensive mechanism of oral angiotensin I converting enzyme inhibitor (captopril) in renin-independent essential hypertension]. 631 35


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