Local blood flow regulation in normotensive man during prolonged treatment with propranolol.

The influence of propranolol on blood flow in peripheral tissues was studied in 10 normotensive subjects. Adequacy of beta-blockade was ascertained by an ergometric test. Perfusion of the subcutaneous tissue and skeletal muscle was measured by the local 133Xe-washout technique. The arteriolar dilatation underlying the autoregulatory response to a decrease in arterial perfusion pressurehead was not affected by beta-blockade. Propranolol did not change the magnitude of arteriolar constriction elicited by the local sympathetic veno-arteriolar reflex. Thus, the locally induced increase in the discharge rate along the peripheral sympathetic adrenergic fibres did not lead to measurable change in beta-receptor activity. The present results indicate that local bloodflow regulatory mechanisms are not affected by propranolol. They also indicate that the direct peripheral effects of propranolol are of no clinical importance in normotensive subjects in the supine position, when the general activity in the sympathetic nervous system is low.