Effect of peroral administration of sotalol on the hemodynamics of the baboon.

Abstract

We investigated the effect of oral administration of sotalol on coronary and renal blood flow and other hemodynamic parameters of the baboon. Measurements were made in anesthetized baboons under basal conditions and during the intravenous infusion of isoproterenol at rates of 0.5, 1.0, 2.0 microgram. min-1 in an experimental (n = 20) and a control (n = 6) group. Subsequently, sotalol (dose 1-4 mg.kg-1, mean 2.25 mg.kg-1) or placebo was administered. After 2 h the procedure was repeated. Measurements included renal (RBF) and coronary (COR BF) blood flow, cardiac output (CO), heart rate (HR), stroke volume (SV), left ventricular systolic pressure (LVSP), maximum positive dP/dt (dP/dt max), aortic diastolic (APD) and mean (APM) pressures, heart rate-left ventricular systolic pressure product (RPP), and left ventricular stroke work index (LVSWI). RBF and COR BF were determined indirectly from the rate of 133 Xe clearance. In the control group, changes before and after the administration of placebo did not differ significantly for all parameters. In the experimental group, changes after sotalol administration were significantly lower for COR BF, CO, HR, LVSP, dP/dt max, APD, APM and RPP, but were not significantly different for RBF, SV and LVSWI. Beta-blockade had no effect on RBF. The reduction in COR BF was associated with a reduction in RPP (myocardial oxygen consumption). However, the oxygen supply-demand relationship was maintained. Decrease in CO was largely due to reduction in HR since SV (and LVSWI) were unaffected by Beta-blockade.