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Biomedical subjects

H R Brunner

Publications and source records attributed to H R Brunner.

At least 397 records · Page 22Linked to original sources
PubMed1985

Isolated perfused mesenteric arteries of hypertensive and normotensive rats; response to norepinephrine, lysine vasopressin and angiotensin II.

The aim of this study was to assess the pressure response of mesenteric arteries isolated from various hypertensive rat models to the 3 pressor agonists norepinephrine, lysinevasopressin and angiotensin II. The isolated mesenteric arterial beds were perfused with a Krebs-solution and then exposed to increasing doses of the 3 different pressor agents. Compared to Wistar Kyoto controls, spontaneously hypertensive rats exhibited a clearly enhanced vascular response to norepinephrine and lysine vasopressin but not to angiotensin II. In animals with hypertension produced by angiotensin II continuously released by an osmotic micropump, the vascular response to lysine vasopressin and angiotensin II was increased while that to norepinephrine was unchanged. Rats rendered hypertensive by the administration of deoxycorticosterone and salt exhibited an increased vascular response exclusively to angiotensin II. In all models taken together, the magnitude of the vascular response to norepinephrine and lysine vasopressin was related to the blood pressure of the intact animal but this was not the case for angiotensin II. These observations are not incompatible with the concept that changes in the vascular response are predominantly due to structural changes of the vascular wall. However, they suggest that more specific alterations of responsiveness of the vascular smooth muscle must also take place.

Angiotensin II↗
PubMed1985

Enhanced renin secretion in adrenalectomized rats with glucocorticoid-induced hypertension.

The role of circulating epinephrine in the regulation of renin release was studied in unanesthetized rats with glucocorticoid-induced hypertension. Biadrenalectomized Wistar rats were made hypertensive with methylprednisolone (20 mg/kg s.c. weekly) for 2 weeks and supplemented with deoxycorticosterone pivalate (10 mg/kg s.c. weekly). Sham-operated controls received the same treatment. Baseline weight, mean intra-arterial blood pressure and heart rate of the groups were the same. In both adrenalectomized and sham-operated rats plasma renin activity was determined after a 30 min infusion of the beta-adrenoceptor stimulant isoproterenol (40 ng/min) or its vehicle. Isoproterenol had no blood pressure effect and accelerated heart rate to a similar extent in rats with and without adrenals. Plasma renin activity was significantly higher in epinephrine-deficient than in sham-operated rats. Renin secretion was significantly enhanced by isoproterenol in both groups of rats. These data therefore indicate that in rats with glucocorticoid-induced hypertension the renin-angiotensin system is activated by adrenalectomy, despite the fact that adrenal insufficiency cannot develop. It also appears that rats lacking of circulating epinephrine for a prolonged period do not exhibit an abnormal responsiveness of renin secretion to the stimulation of renal beta-adrenoceptors.

Adrenalectomy↗
PubMed1985

Double-blind comparison of indapamide with a placebo in hypertensive patients treated by practicing physicians.

The antihypertensive effect of indapamide (2.5 mg/day) was compared to that obtained with a placebo in a controlled trial carried out by 11 physicians in their private practice. Thirty-one patients with uncomplicated essential hypertension were included. After a run-in period of 3 weeks without any treatment, either indapamide (n = 16) or a placebo (n = 15) were administered for 8 weeks in double-blind fashion. Blood pressure decreased in both groups. In patients treated with indapamide, systolic pressure was significantly lower than in those given the placebo at 3 out of the 4 follow-up visits; diastolic pressure, however, was significantly lower only at the end of the trial. Both the active drug and the placebo were well tolerated. No significant change in body weight, plasma potassium and uric acid occurred during the study in either group of patients. It appears therefore that indapamide, at a dose which apparently has no major diuretic effect, may be useful for practitioners in managing patients with mild to moderate hypertension.

Adult↗
PubMed1985

Plasma angiotensins under sustained converting enzyme inhibition with enalapril in normal humans.

During converting enzyme inhibition, a striking difference is found between plasma immunoreactive angiotensin (ANG) II and ANG-(1-8)octapeptide as specifically measured after high performance liquid chromatography (HPLC). The relative contributions to this difference of cross-reacting ANG I and shorter ANG peptides other than (1-8)octapeptide are not known. Eight normal volunteers were given a daily single oral dose of enalapril (20 mg) for 4 days. Plasma levels of ANG-(1-8)octapeptide, (2-8)heptapeptide, (3-8)hexapeptide and (4-8)pentapeptide as well as blood concentrations of ANG I and plasma angiotensin converting enzyme activity were measured before and 4 h post drug on the first and the last day of treatment. Plasma peptides were extracted with bonded-phase silica and separated by isocratic reversed-phase HPLC before radio-immunoassay. Significant cross-reactivity of an antiserum permitted the individual measurement of different ANG peptides and metabolites in plasma. During converting enzyme inhibition, the plasma levels of ANG metabolites tended to decrease, but they remained measurable. Thus, depending on the specificity of the antiserum used, conventional measurement of immunoreactive ANG II underestimates to various degrees the inhibition of angiotensin converting enzyme.

Adult↗
PubMed1985

Response of plasma vasopressin to changes in extracellular volume and/or plasma osmolality in patients on maintenance hemodialysis.

The effect of changes in extracellular volume versus changes in plasma osmolality on arginine vasopressin (AVP) release was studied in 6 patients with terminal renal failure maintained on chronic hemodialysis. The day of the study, the patients were treated by sequential ultrafiltration lasting 1 hour followed by a 3-hour conventional hemodialysis session. The ultrafiltration resulted in the removal of 460 to 1,170 ml (mean = 860 ml) of volume. Body weight during the combined procedures fell by 1.6 +/- 0.4 kg (mean +/- s.e.m.) while mean arterial pressure decreased only slightly. Plasma osmolality was unaffected by sequential ultrafiltration, but decreased from 313 +/- 4 mosm/kg H2O to 291 +/- 4 mosm/kg H2O during hemodialysis. Initial plasma AVP concentration was high at 4.45 +/- 0.25 pg/ml and remained unchanged during the sequential ultrafiltration at 4.55 +/- 0.37 pg/ml, but it fell during the hemodialysis to 2.47 +/- 0.45 pg/ml. A hypotensive episode observed in one patient towards the end of hemodialysis resulted in a sharp increase in plasma AVP concentration from 5.5 to 18 pg/ml. During the combined procedures, plasma AVP and plasma osmolality showed a close and linear correlation (r = 0.63, n = 23, p less than 0.001). These findings suggest that in patients on maintenance hemodialysis, changes in plasma osmolality play a predominant role in determining AVP secretion whereas a marked decrease in volume without ensuing hypotension has no effect on AVP release.

Blood Pressure↗
PubMed1984

[Role of vasopressin in reducing the cutaneous blood flow induced by cigarette smoke].

The authors demonstrate that skin vasoconstriction induced by cigarette smoking in normal volunteers is due to a concomitant enhancement of arginine vasopressin release. The skin blood flow reduction after smoking was more pronounced in the subjects reaching the highest levels of arginine vasopressin, and this effect no longer developed after administration of a specific vasopressin antagonist acting at the vascular site.

Adolescent↗
PubMed1984

[Role of bradykinin in hypotension induced by the active factor derived from factor XII].

The active fragment derived from factor XII (factor XIIf) was purified from human plasma and administered intravenously to normotensive conscious rats. Factor XIIf-mediated hypotension was dose-dependent and augmented by pretreatment with captopril, an inhibitor of the angiotensin I- and bradykinin-processing enzyme. In contrast, factor XIIf-induced hypotension was not enhanced by blockade of the renin-angiotensin system by saralasin, a competitive antagonist of angiotensin II at the vascular receptor level. These results suggest that factor XIIf-mediated hypotension is due to the formation of bradykinin.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1984

Deterioration of renal function in hypertensive patients with scleroderma despite blood pressure normalization with captopril.

The orally active angiotensin-converting enzyme inhibitor captopril was administered for up to 11 weeks to three patients with progressive systemic sclerosis presenting with hypertension and plasma creatinine levels of 3.1, 7.2 and 10.4 mg/100 ml. Only one patient had malignant phase hypertension. In this patient a diuretic had to be added to captopril in order to keep blood pressure under control. Despite sustained blood pressure control during captopril administration, renal function deteriorated and hemodialysis treatment had to be started in all patients. Up to that time no substantial improvement in skin lesions was observed. During the period of dialysis, blood pressure was normal in all patients even though administration of captopril was discontinued. All three patients died of respiratory failure while on chronic hemodialysis for 3 to 4 weeks. These observations confirm that angiotensin-converting enzyme inhibition may be helpful in controlling blood pressure of patients with scleroderma. However, in contrast to some earlier reports, they also indicate that converting enzyme inhibition does not always prevent the multivisceral vascular lesions of scleroderma.

Acute Kidney Injury↗
PubMed1984

[Acute renal insufficiency following inhibition of the angiotensin conversion enzyme by various agents].

At a two years' interval, a patient with severe hypertension was treated with captopril and MK 521, two different angiotensin converting enzyme inhibitors. Each time the blood pressure decreased to normal levels after addition of diuretic therapy but the patient developed acute renal failure. On both occasions the interruption of the inhibitors restored renal function very rapidly. In this woman, considered to suffer from essential hypertension on the basis of a normal intravenous pyelogram, arteriography showed bilateral renal-artery stenosis.

Acute Kidney Injury↗
PubMed1984

A potent converting enzyme inhibitor CGS 13928C. Drug profile in normal volunteers.

The converting enzyme inhibitor CGS 13928C was evaluated in 15 healthy male volunteers. First the efficacy of a single oral dose of 0.5, 1, 2 or 5 mg in antagonizing the pressor response to exogenous angiotensin I was tested with continuous monitoring of the blood pressure and heart rate by an intraarterial catheter. CGS 13928C 1, 2 and 5 mg consistently reduced the response to angiotensin within 2 to 3 h and for a period exceeding the 4 h of monitoring. The 2 mg dose was hardly more effective than 1 mg and 5 mg did not further enhance the blockade. Subsequently, plasma renin and converting enzyme activity, angiotensin I, angiotensin II and aldosterone were measured serially before and up to 72 h following oral administration of either 1 mg (n = 7) or 2 mg (n = 8) CGS 13928C. As expected, plasma renin activity and angiotensin I rose, while plasma converting enzyme activity, angiotensin II and aldosterone fell following both doses of the drug. No side-effects occurred. In normal volunteers CGS 13928C is an effective and extremely potent, orally active converting enzyme inhibitor.

Adult↗
PubMed1984

Ambulatory blood pressure recording to identify hypertensive patients who truly need therapy.

Ambulatory blood pressure profiles were obtained with the Remler system, a portable semi-automatic blood pressure recorder, in 245 untreated patients considered by their physician to be hypertensive. The average blood pressures recorded during the usual daily activities of the patients were greater than 140 mmHg for the systolic and greater than 89 mmHg for the diastolic in only 96 (39%) and 107 (44%) of them respectively. Blood pressure monitoring in ambulatory patients appears to be useful for the practitioner to detect those patients who require antihypertensive therapy. Possibly, unnecessary therapy of only seemingly hypertensive patients may be avoided by this technique.

Adolescent↗
PubMed1984

Effect of centrally acting antihypertensive drugs on the renin-angiotensin system and vasopressin.

Such compounds as clonidine, guanabenz and guanfacine, which stimulate central alpha-adrenoceptors, reduce blood pressure predominantly by reducing sympathetic outflow. Notwithstanding, they also tend to reduce renin secretion, aldosterone, and even vasopressin levels. In some clinical settings, inactivation of the renin-angiotensin system may contribute to their antihypertensive effect. In addition, the absence of sodium retention, which appears to be a special feature of guanabenz, may also have a beneficial effect on blood pressure. In contrast, it is unlikely that a decrease in vasopressin secretion has any major influence on blood pressure.

Adrenergic alpha-Agonists↗
PubMed1984

Response of plasma arginine vasopressin levels to rapid changes in altitude.

Plasma arginine vasopressin levels were studied in 15 normal working men exposed at 4-day intervals to a rapid increase or decrease in altitude of 2000 m. Plasma arginine vasopressin levels were significantly lower (P less than 0.001) at the higher altitude though plasma osmolality did not change. It is concluded that the important diuresis known to physiologically occur in response to high altitude may be related to a decrease in antidiuretic hormone release.

Adaptation, Physiological↗