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Biomedical subjects

H R Brunner

Publications and source records attributed to H R Brunner.

At least 451 records · Page 25Linked to original sources
PubMed1982

Enalapril maleate and a lysine analogue (MK-521) in normal volunteers; relationship between plasma drug levels and the renin angiotensin system.

1 Two single doses of 10 mg each of the converting enzyme inhibitor enalapril maleate or MK-421 and of its lysine analogue (MK-521) were administered p.o. to twelve male volunteers. 2 The active diacid metabolite of MK-421 and the lysine analogue were determined by radioimmunoassay and MK-421 by the active metabolite method following in vitro hydrolysis. 3 Peak serum levels of MK-421, active metabolite and lysine analogue were reached within 1, 3 to 4, and 6 h respectively. Practically all MK-421 had disappeared from serum within 4 h. 4 A close correlation between percent inhibition of plasma converting enzyme activity and the serum concentration of active metabolite was observed ( r = 0.98, n = 171, P less than 0.001). Similarly, converting enzyme blockade as expressed by the ratio plasma angiotensin II/angiotensin I was closely correlated with serum active metabolite levels (r = 0.93, n = 15, P less than 0.001).

Adult↗
PubMed1982

Escape from mineralocorticoid excess: the role of angiotensin II.

Escape from the sodium-retaining action of mineralocorticoids coincides with the suppression of plasma renin and angiotensin II levels. The purpose of this study was to evaluate whether blockade of the renin system accelerates this escape. Eight male normotensive volunteers, aged 24--33 yr, were maintained during two subsequent periods of 12 days each, separated by 3--4 weeks, on a constant intake of sodium and potassium of 140 mmol/day. During both periods, fludrocortisone acetate (0.2 mg) was administered orally three times a day on days 4--12. In addition, on days 3--12, either a converting enzyme inhibitor (MK 421;20 mg orally, twice daily) or a placebo was added in double blind fashion and randomized sequence. During both periods, blood pressures were similar; they tended to increase slightly toward day 12. The weight increase did not differ between the two periods. With MK 421, angiotension II levels were significantly lower than with placebo on days 3--6 (P less than 0.001). On the same days, PRA was increased due to converting enzyme blockade. Despite the significantly different angiotensin II levels on days 3--6, daily urinary sodium excretion on all individual days as well as cumulative sodium balance were the same during both periods. Therefore, we could find no evidence in man that suppression of circulating angiotensin II levels is causally related to escape from mineralocorticoid excess.

Adult↗
PubMed1982

Effects of the new oral angiotensin converting enzyme inhibitor MK-421 in human hypertension.

"MK-421" a new oral converting enzyme inhibitor was administered to 16 hypertensive patients in doses ranging between 2.5-40 mg once daily for periods of 6-18 weeks. The blood pressure, plasma renin activity, plasma angiotensin II, aldosterone and angiotensin converting enzyme activity were assessed before and during treatment. Blood pressure normalized in 11 patients and decreased significantly in the remaining 5, without significant changes in heart rate or orthostatic hypotension. At 24 hrs after the first effective dose, plasma renin activity remained elevated to 228% whereas plasma angiotensin II was suppressed to 58%, aldosterone was suppressed to 40% and angiotensin converting enzyme activity was suppressed to 16% of the baseline. Magnitude of blood pressure decrement achieved with the maximal dose did not correlate with baseline plasma renin activity levels. No side-effects were noted during the 6-18 week period of observation.

Administration, Oral↗
PubMed1982

Evidence for a sodium-induced activation of central neurogenic mechanisms in one-kidney, one-clip renal hypertensive rats.

The mechanisms sustaining high blood pressure in conscious one-kidney, one-clip Goldblatt rats were evaluated with the use of SK&F 64139, a phenylethanolamine N-methyltransferase inhibitor capable of crossing the blood-brain barrier and of captopril, an angiotensin converting enzyme inhibitor. The rats were studied 3 weeks after left renal artery clipping and contralateral nephrectomy. During the developmental phase of hypertension, two groups of rats were maintained on a regular salt (RNa) intake, whereas two other groups were given a low salt (LNa) diet. On the day of the experiment, the base-line mean blood pressure measured in the LNa rats (177.4 +/- 5.2 mm Hg, mean +/- S.E., n = 15) was similar to that measured in the RNa rats (178.7 +/- 5.4 mm Hg, n = 16). SK&F 64139 (12.5 mg p.o.) induced a significantly more pronounced (P less than .001) blood pressure decrease in the RNa rats (-25.6 +/- 3.6 mm Hg, n = 8) than in the LNa rats (-4.3 +/- 3.3 mm Hg, n = 7) during a 90-min observation period. On the other hand, captopril (10 mg p.o.) normalized blood pressure in LNa rats (n = 8), but produced only a 13.4 mm Hg blood pressure drop in RNa rats (n = 8). RNa rats treated with SK&F 64139 were found to have decreased phenylethanolamine N-methyltransferase activity by an average 80% in selected brain stem nuclei when compared with nontreated rats. No significant difference in plasma catecholamine levels was found between the RNa and LNa rats. These results suggest that, in this experimental model of hypertension, the sodium ion might increase the model of hypertension, the sodium ion might increase the vasoconstrictor contribution of the sympathetic system via a centrally mediated neurogenic mechanism while at the same time it decreases the renin-dependency of the high blood pressure.

Animals↗
PubMed1982

Hypertension in a patient with hypercalcemia: captopril and verapamil.

A 38-year-old woman with hypercalcemia, severe hypertension, and high renin levels was treated with the angiotensin-converting enzyme inhibitor captopril. This therapy, together with spironolactone, normalized blood pressure (BP), but even with three daily administrations of the converting enzyme inhibitor, intermittent rebound hypertension could not be avoided. The administration of only verapamil, an antagonist of calcium transport, did not induce BP control, but when verapamil therapy was combined with administration of captopril and spironolactone, BP could be normalized with only twice-daily administration of the converting enzyme inhibitor. Thus, high plasma calcium levels seem to sensitize the arterioles to the intermittent increase of angiotensin II levels that accompanies captopril therapy.

Adult↗
PubMed1981

Antihypertensive effect of the new oral angiotensin converting enzyme inhibitor "MK-421".

The effects of the new oral converting enzyme inhibitor "MK-421" on blood pressure, plasma renin activity, plasma angiotensin II, aldosterone, and angiotensin converting enzyme were assessed in 16 hypertensive patients. Maximum (maintenance) doses ranged from 2.5 mg-40 mg daily. Blood pressure decreased from 177 +/- 7/111 +/- 4 mm Hg to 145 +/- 6/94 +/- 3 mm Hg supine and from 174 +/- 7/177 +/- 4 mm Hg to 142 +/- 6/101 +/- 3 mm Hg upright (mean +/- SEM, p less than 0.001 for both). Heart rate did not change significantly. Plasma renin activity rose during treatment, whereas plasma angiotensin II, aldosterone, and angiotensin converting enzyme remained suppressed at 24h after the maximum dose. Magnitude of blood pressure reduction after the maximum dose did not correlate with baseline plasma renin activity levels. No side-effects were noted during the 2-10 week observation period. MK-421 is similar to its predecessors in efficacy and clinical and biochemical correlates, the main difference being its higher potency and longer duration of action.

Administration, Oral↗
PubMed1981

[Treatment of refractory ascites by means of the LeVeen shunt].

Amongst the surgical treatments that have been suggested for refractory ascites, the one that has met with the greatest success is the LeVeen shunt. It nevertheless involves certain risks and might even be fatal. The authors' brief experience in this domain has confirmed its positive immediate effects and has also brought to light some of its drawbacks. The large number of potential complications leads one to conclude that the LeVeen shunt should be reserved for refractory ascites and hepato-renal syndrome, and should not be prematurely employed in other situations.

Aldosterone↗
PubMed1981

Three new long-acting converting-enzyme inhibitors: relationship between plasma converting-enzyme activity and response to angiotensin I.

Three new angiotensin converting-enzyme inhibitors were given orally to 20 men in single doses ranging from 1.25 to 40 mg. Two of them induced comparable marked inhibition of both the blood pressure response to exogenous angiotensin I and plasma converting-enzyme activity. Onset of action was relatively slow, but 21 to 24 hr after drug plasma converting-enzyme activity was still clearly reduced. The third was less active. There was a close correlation between blood pressure response on administration of angiotensin I and plasma converting-enzyme activity. There were no adverse effects. These new drugs are interesting because of their long duration of action. The measurement of plasma converting-enzyme activity seems useful for monitoring efficacy of converting-enzyme blockade and compliance to therapy.

Adult↗
PubMed1981

Effects of the oral angiotensin-converting enzyme inhibitor MK-421 in human hypertension.

1. The effects of the new oral angiotensin-converting enzyme (ACE) inhibitor MK-421 on blood pressure, plasma renin activity, angiotensin-II, aldosterone and converting enzyme activity were assessed in 16 hypertensive patients followed for 6--18 weeks. 2. After an initial titration period, maintenance doses of 2.5--40 mg once daily produced satisfactory blood pressure control in 11 and a partial but significant decrease in the remainder. 3. Treatment was associated with no change in heart rate and no orthostatic hypotension. At 24 h after the first effective dose, blood pressure was still decreased, plasma ACE was suppressed to 16% of the baseline, plasma angiotensin to 58%, aldosterone to 42%, and plasma renin activity was elevated to 228% of the baseline. 4. Magnitude of blood pressure fall was significantly correlated with the height of pretreatment blood pressure but not with baseline levels of plasma renin activity.

Adult↗
PubMed1981

Effect of a new angiotensin converting enzyme inhibitor MK 421 and its lysine analogue on the components of the renin system in healthy subjects.

1 MK 421 and its lysine analogue are two new inhibitors of angiotensin converting enzyme. Ten mg of both compounds were each given p.o. to 12 normotensive volunteers to determine their effect on the various components of the renin angiotensin aldosterone system. 2 Plasma converting enzyme activity decreased to very low levels within 3 to 4 h to recover only slowly over the next 72 h. Plasma angiotensin II and aldosterone also fell but returned to baseline within 24 h, whereas plasma renin activity rose reflecting the low angiotensin II levels. 3 There was a close correlation between both angiotensin II and aldosterone levels and the logarithm of plasma converting enzyme activity demonstrating that angiotensin II and aldosterone fell only when converting enzyme activity was reduced to very low levels. 4 Mean hourly urinary sodium excretion increased markedly 6 to 10 h post-drug, while blood pressure decreased slightly. Both drugs were well tolerated. 5 Thus 10 mg of MK 421 or its lysine analogue given orally are effective and long acting angiotensin converting enzyme inhibitors.

Adult↗
PubMed1981

RHC 3659: a new orally active angiotensin converting enzyme inhibitor in normal volunteers.

1 The new converting enzyme inhibitor RHC 3659 was tested in 15 male volunteers. The study consisted of two parts: first, the ability of a single oral dose (5, 10, 20, 40 or 80 mg) to inhibit the pressor response to exogenous angiotensin I was tested with blood pressure and heart rate monitored continuously through an intraarterial catheter. A dose-related shift to the right of the pressor response curve to angiotensin I was observed with a peak occurring within 0.5 to 1 h. The pressor response to angiotensin II was unaffected. 2 In the second part, plasma renin and converting enzyme activity, angiotensin II and aldosterone were measured serially before and up to 8 h after administration of a single oral dose of RHC 3659. As expected. plasma angiotensin II and aldosterone fell within 30 min while plasma renin activity increased. Plasma converting enzyme activity was suppressed at 0.5 h in a dose-related manner with levels still below 30% of control 4 h following 80 mg of the inhibitor. 3 However, in vitro the enzyme-inhibitor complex seemed quited fragile since during storage of the plasma samples at -20 degrees C, converting enzyme activity increased significantly already within days (P less than 0.001, n = 28) and continued to rise for more than 2 months. This fragility may explain the seemingly lower potency of RHC 3659 when compared to captopril. No side effects were observed.

Adult↗
PubMed1981

Role of vasopressin, catecholamines, and plasma volume in hypertonic saline-induced hypertension.

Elevation of blood pressure induced by an acute sodium and fluid load in the anephric state has been attributed to intravascular fluid volume expansion. The present experiments were designed to study the role of vasopressin and catecholamines in this type of hypertension. Normotensive anephric rats, adrenergically intact or pretreated with alpha- and beta-adrenoceptor blockade, and deoxycorticosterone (DOC)-salt-treated anephric rats, intact or pretreated with alpha- and beta-adrenoceptor blockade, received an infusion of 2 ml containing 3 meq NaCl, followed by intravenous administration of an analogue antagonist of the vasopressor effect of arginine-vasopressin (AVP). Pressure increments induced by hypertonic saline were abolished by an AVP antagonist partly in the adrenergically intact animals (leaving a small residual pressure elevation) and completely in adrenergically blocked animals, which had a larger AVP component. Volumes expansion did not necessarily accompany increase in blood pressure after saline infusion. In fact some DOC-salt-treated animals with the highest blood pressures and norepinephrine levels exhibited contraction of plasma volume. Increments in blood pressure were negatively correlated with plasma volume changes (r = -0.687, P less than 0.05) in these animals and positively with norepinephrine levels in all adrenergically intact animals (r = 0.818, P less than 0.001). It is concluded that the hypertensive response elicited by acute hypertonic saline load is due to vasoconstriction mediated partly by vasopressin and partly by the sympathetic system, which may in some way attenuate the effect of vasopressin.

Animals↗
PubMed1981

The opposing effects of chronic angiotensin-converting enzyme blockade by captopril on the responses to exogenous angiotensin II and vasopressin vs. norepinephrine in rats.

To study the influence of acute and chronic angiotensin-converting enzyme blockade on the pressor response to exogenous angiotensin II, vasopressin and norepinephrine, we gave normal female Wistar rats 100 mg of captopril or 1 ml of 5% glucose twice daily by gavage for 2 weeks. On the 15th day, rats were anesthetized with pentobarbital, and dose-response curves to angiotensin II, lysine-vasopressin, and norepinephrine were obtained before and after intraperitoneal injection of 100 mg/kg of captopril or 1 ml of 5% glucose. Acute as well as chronic converting enzyme blockade enhanced the pressor response to exogenous angiotensin II. Similarly, sensitivity to exogenous vasopressin was increased by both acute and chronic converting enzyme inhibition. In contrast, chronic converting enzyme blockade significantly blunted the response to exogenous norepinephrine, whereas acute blockade tended to accentuate its pressor effect. These results suggest that chronic angiotensin-converting enzyme blockade may partly inhibit sympathetic activity which, in turn, might contribute to the antihypertensive efficacy of this therapeutic approach. These results also point to an important physiological interaction between the two pressor hormones, angiotensin II and vasopressin.

Angiotensin II↗
PubMed1981

Immersion and venous occlusion plethysmography in patients with idiopathic orthostatic hypotension.

In 3 patients suffering from idiopathic orthostatic hypotension (Shy-Drager's syndrome) venous distensibility was measured by occlusion plethysmography in supine and upright position. In this latter position, venoconstriction was absent, contrasting with the marked venoconstriction observed in normal volunteers studied under identical conditions. Venous occlusion plethysmography therefore seems to be useful to detect the autonomic defect leading to venous pooling. These patients were also immersed in water to the mid-abdomen while standing. This maneuver fully abolished orthostatic hypotension. Immersion is useful in motivating these patients to accept treatment by counterpressure garments, and makes early active physiotherapy possible.

Aged↗
PubMed1981

Uncontrollable hypertension in patients on hemodialysis: long-term treatment with captopril and salt subtraction.

It has been suggested that an inappropriate relationship between renin and exchangeable sodium is responsible for the hypertension of patients with chronic renal failure. Long-term blockade of the renin system by captopril made it possible to test this hypothesis in 8 patients on maintenance hemodialysis. Captopril was administered orally in 2 daily doses of 25 to 200 mg. Previously, blood pressure averaged 179/105 +/- 6/3 (mean +/- SEM) pre- and 182/103 +/- 7/3 mm HG post-dialysis, despite intensive ultrafiltration and conventional antihypertensive therapy. The 4 patients with the highest plasma renin activity normalized their blood pressure with captopril alone, whereas in the 4 remaining patients, captopril therapy was complemented by salt subtraction which consisted in replacement of 1-2 liters of ultrafiltrate by an equal volume of 5% dextrose until blood pressure was controlled. After an average treatment period of 5 months, blood pressure of all 8 patients was reduced to 134/76 +/- 7/5 mm Hg (P less than 0.001) pre- and 144/81 +/- 9/5 mm Hg (P less than 0.001) post-dialysis without a significant change in body weight. The present data suggest that captopril alone or combined with salt subtraction normalizes blood pressure of patients on chronic hemodialysis with so called uncontrollable hypertension.

Adolescent↗