The haemodynamic effects of prenalterol, a new sympathomimetic agent, have been studied in anaesthetized open-chest pigs with acute myocardial ischaemia provoked by left anterior descending coronary artery ligation. A group of eight animals was infused with saline and served as control (C). In both groups the ligation of the left anterior descending coronary artery determined a significant (P less than 0.05) reduction of aortic flow, maximum left ventricular (LV) dp/dt with no changes in heart rate. The infusion of a first dose of 30 micrograms/kg of prenalterol restored the depressed haemodynamics but increased significantly the heart rate in the prenalterol group while the saline infused group did not show any significant changes. The haemodynamic effects of prenalterol were still evident 25 min after the infusion. The subsequent administration of a second dose of 60 micrograms/kg of prenalterol resulted in a further improvement of the aortic flow, LV dp/dt and heart rate which reached values higher than in the basal condition. The positive inotropic effect was not associated with changes in stroke volume, therefore the increase in aortic flow was essentially due to an increase of the heart rate. It is concluded that prenalterol is a powerful inotropic agent in acutely infarcted animals. Its action on aortic flow appears to be related to an increase in heart rate in contrast to some previous observations.

Animals↗

PubMedDate not supplied

Effects of moderate salt restriction on intralymphocytic sodium and pressor response to stress in borderline hypertension.

The effects of a moderate dietary salt restriction on intralymphocytic sodium content and pressor response to stress (mental arithmetic, handgrip, and bicycle exercise) were tested in 25 young subjects with borderline hypertension. The study was performed by a randomized, cross-over, within-patient, experimental design. Diet did not significantly reduce blood pressure at rest but did so significantly in both systolic and diastolic blood pressure during stress and exercise. Variations in diastolic blood pressure induced by stimulation correlated significantly with intralymphocytic sodium content both before and during low-salt diet whereas no correlation was found in the case of systolic blood pressure and heart rate variations. These findings suggest that in young subjects with borderline hypertension, sodium homeostasis and blood pressure regulation are somehow interrelated, and that a moderate dietary salt restriction reduces both intralymphocytic sodium content and pressor response to adrenergic stimulation. This could be useful in preventing the development of sustained hypertension.

Adolescent↗

PubMedDate not supplied

[Rehabilitation of the patient with myocardial infarct].

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Humans↗