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Biomedical subjects

F Rengo

Publications and source records attributed to F Rengo.

At least 199 records · Page 11Linked to original sources
PubMed1979

[Changes in plasma renin activity induced by acute administration of nifedipine in hypertensive patients (author's transl)].

In the present study we assessed plasma renin activity (PRA) variations induced by Ca++ antagonist antihypertensive drug Nifedipine in 8 normoreninaemic or hyporeninaemic hypertensive patients. On two successive days three venous blood samples were sampled, two in clinostatic position and the last one 120 min later in orthostatic position; on the second day 20 mg of nifedipine were administered sublingually. Nifedipine increases significantly PRA after orthostatic position compared with starting conditions (p < 0.01) and compared with the values recorded without the drug at the same times (p < 0.01). Both systolic and diastolic blood pressure decreased 15 and 120 min after nifedipine administration while heart rate increased at the same times. Acute nifedipine administration augments PRA in hypertensive subjects; explanatory hypoteses are proposed.

Humans↗
PubMed1978

Relation between cholinergic and histaminergic components in reflex vasodilatation in the dog.

Previous studies have shown that phentolamine is able to reverse the reflex vasodilatation produced by transitory baroreceptor stimulation by blocking sympathetic, histaminergic, and cholinergic components. A direct anticholinergic action of phentolamine has never been described; however, since it is known that this drug is capable of inhibiting histamine release during the reflex vasodilatation, it is possible that its ability to block the cholinergic component of the reflex is related to the latter property. Therefore, this study was undertaken in an attempt to identify possible relationships between cholinergic and histaminergic components of the reflex vasodilatation. Accordingly, in mongrel dogs the gracilis muscle was isolated and perfused and then loaded with 14C-labeled histamine. A transitory systemic hypertension was induced by intravenous injection of norepinephrine; this produced a reflex vasodilatation, shown by the fall in perfusion pressure, which was accompanied by an increase of histamine release from the muscle. Vagal block induced by atropine pretreatment reduced the fall in perfusion pressure induced by the systemic hypertension and produced a reduction of histamine release during the vasodilatation. In another group of animals a vasodilatation in the perfused muscle was induced by injection of acetylcholine. This response was accompanied by an increase in histamine release from the gracilis muscle. Alpha-receptor blockade, which has been shown to inhibit histamine release, reduced this acetyl-choline-induced vasodilatation. These results, while confirming the participation of the cholinergic system in the reflex vasodilatation elicited by transitory stimulation of the arterial baroreceptors, seem to demonstrate that this component is mediated almost exclusively by histamine release.

Acetylcholine↗
PubMed1978

Studies on the mechanism of reflex vasodilatation. The cholinergic component in the baroreceptorial reflex in the dog.

This study was designed to investigate whether the cholinergic system is involved in the genesis of the reflex vasodilatation which follows the systemic hypertension induced by fast intravenous injection of norepinephrine in the dog. Accordingly, in 7 dogs the gracilis muscle was isolated and perfused and the reflex evoked. The analysis of the integrated areas of vasodilatation after atropine pretreatment showed a significant decrease of the reflex response in the perfused circulation. In fact, the mean value of the integrated areas of vasodilatation which was 66 +/- 8 mm Hg/min in the control condition, was reduced to 45 +/- 4 mm Hg/min after administration of atropine in the gracilis artery; meanwhile the integrated areas of systemic hypertension did not show any change. Phentolamine intra-arterial administration completely abolished the reflex. These results suggest the existence of a cholinergic component in the reflex vasodilatation induced by transitory baroreceptorial stimulation.

Animals↗
PubMed1978

Correlation between systolic time intervals and roentgen findings in normal subjects and cardiopathic patients.

This study was designed to evaluate the usefulness of non-invasive parameters in the follow-up of cardiopathic patients without valvular cardiac diseases. In 49 patients suffering from heart disease we have studied the changes of radiologic cardiac measurements and systolic time intervals (STI) in the 4 functional classes of the NYHA classification, investigating also the existence of any relationship between these different parameters. Only the patients in the 3rd and the 4th functional classes showed significant changes in STI and radiologic measurements, as compared with the control group. Moreover, significant negative correlations have been observed between relative heart volume and LVET (r = 0.69, P less than 0.001) and LVETc (r = 0.82, P less than 0.001) and positive correlations between relative heart volume and PEP (r = 0.59, P less than 0.01) and PEP/LVET ratio (r = 0.75, P less than 0.001). These results, while confirming the close correlation between STI and cardiac performance, seem to demonstrate that relative heart volumetry is a fairly accurate index of the cardiac conditions in non-valvular heart diseases.

Adult↗
PubMed1978

[Efficacy and tolerability of a cardioselective beta-blocking drug (atenolol) in the treatment of essential hypertension. A double blind study (author's transl)].

The antihypertensive effect of atenolol, a new beta 1 receptor blocking agent, was studied in a double blind non cross-over trial in 40 patients (pts) affected by mild to moderately severe essential hypertension with normal plasma renin activity. After a run-in period (15 days) of placebo treatment pts were assigned to two groups. The first (group A) continued placebo treatment for 30 days, the second (Group B) were given atenolol (ICI 66082) 100 mg daily for 30 days also. Atenolol significantly reduced systolic and diastolic blood pressure in recumbent and standing position and heart rate at rest. No significantly changes of the same parameters were observed in group A. Body weight and plasma renin activity was unchanged in both groups. Atenolol treatment never was discharged in order to side effects. These results seem to suggest that atenolol can be an useful drug in the treatment of systemic blood hypertension.

Adult↗
PubMed1978

[Effects of nifedipine in the treatment of effort stable angina: a double blind study (author's transl)].

The effectiveness of chronic treatment with nifedipine in patients (pts) with a history of stable angina on effort has been evaluated in a double-blind study in 15 subjects of both sexes, aged 45 to 65 years. All pts underwent diagnostic cardiac catheterization and selective coronary angiography, which showed stenosis of one or two main coronary vessels between 50 and 70%. The pts, after 2 weeks of observation, underwent erect bicycle exercise test with increasing workloads. After 4 weeks of treatment with nifedipine or placebo the stress test was repeated. Nifedipine treatment reduced the weekly number of anginal attacks as well as the weekly number of nitroglycerin tablets consumed by the pts, increased maximum workload tolerated and reduced the S-T segment depression for the same workload, meanwhile heart rate and blood pressure did not change significantly either at rest or during exercise. The result of this study indicate that nifedipine is useful in the treatment of pts with stable angina on effort.

Angina Pectoris↗