Search PubMed⌕ Search

Biomedical subjects

J Figueroa

Publications and source records attributed to J Figueroa.

76 records · Page 5Linked to original sources

[Mechanisms of conduction disorders in digitalis poisoning].

Ever since the first papers on the mechanism of the arrhythmias of digitalis were first published, during the first two decades of this century, the issue has been a controversial one. Since the automaticity induced by digitalis intoxication has different characteristics when compared to normal automaticity, it has been suggested that probably the mechanisms for these two types of spontaneous activity are different. It has been recently proposed that the automaticity induced by digitalis intoxication could be secondary to the after potential oscillations described in isolated conducting fibers. In order to test this hypothesis we used two experimental models which allow for a careful analysis of the ectopic activity, without the interference of the sinus rhythm. These studies were done in two groups of animals: one, with electrically isolated atria, was used to analyze supraventricular arrhythmias. The other, with chromic atrioventricular block, was used to study ventricular arrhythmias. The results obtained from these experiments show: 1. High therapeutic doses of digitalis enhance the postpacing inhibition of normal pacemakers; 2. When the ectopic rhythms of digitalis intoxication appear, they show postpacing stimulation; 3. Ectopic activity shows a direct relationship with the rate of the conditioning stimulation, and both the coupling period and the number of premature beats depend on this rate. In view of the similarity between the behavior of these arrhythmias and that of the after potential oscillations, we conclude that these oscillations are responsible for the ectopic automaticity of digitalis intoxication.

Animals↗

[Effect of sub-pressor doses of dopamine on renin secretion in the anesthetized dog].

The effects of dopamine, its precursor L-dopa, and the dopaminergic agonist bromocriptine (BEC), on plasma renin activity (PRA), in pentobarbital anesthetized male dogs were investigated. Infusion of dopamine at a dose which did not change blood pressure ( 4 ug/kg/min) had no effect on the secretion of renin, nor did it produce modifications in the PRA response to furosemide (10 mg i.v.). L-dopa, in single dose of 500 mg (p.o), significantly augmented PRA two hours after administration, and the renin values remained elevated throughout the observation period of 120 minutes. However, BEC (2.5 mg p.o.) produced no changes in PRA during this time period. We conclude that at the dose utilized, dopamine apparently has no influence on the secretion of renin, and does not modify the increase in PRA provoked by diuretic. It is possible that the L-dopa induced augmentation in PRA is due to stimulation of the juxtaglomerular cells, by the noradrenaline formed in peripheral tissues from administered L-dopa.

Animals↗

A guide to common parasitic diseases.

The Primary Health Care Guide to UK Parasitic Diseases is aimed at health professionals working in primary care and offers an easy reference and practical advice on prevention, recognition and management of parasitic disease. Here, some of the key points are summarised.

Humans↗