The Effect of Indoramin on Exercise Performance in Mild Hypertension

Abstract

The alpha 1-adrenoceptor antagonist indoramin is proposed to reduce arterial blood pressure without a concomitantly significant increase in heart rate (HR). The present study involves assessment of the effect of alpha 1-adrenoceptor antagonism in patients with mild hypertension on the HR/oxygen consumption (Vo2) relationship, which has previously been shown to indicate improvement in cardiorespiratory fitness following exercise training. A total of 16 patients with a systolic blood pressure of 140-200 mm Hg and diastolic blood pressure of 95-110 mm Hg were examined. A double-blind, placebo-controlled study design was utilized. Following initial observations, the patients were randomized into one group (a) of seven patients who were given a placebo, indoramin, and finally placebo, and a second group (b) of nine patients who were given the two agents in the reverse order, i.e., indoramin, placebo, indoramin; each intervention lasted for 2 weeks and indoramin was given in a dose of 75 mg/day. Indoramin caused a reduction in the elevation of the computed regression line relating HR to Vo2 (a shift to the right), such that at the same HR a greater Vo2 was attained in 11 of the 16 patients in comparison with the baseline exercise test. Pooled results showed a shift of the HR/Vo2 regression line to the right when indoramin was compared with baseline (p less than 0.05) or placebo. In the same patients, indoramin caused a decrease in arterial blood pressure during exercise relative to baseline or placebo periods, and a decrease in the HR during exercise relative to baseline period, but not when compared with placebo periods.(ABSTRACT TRUNCATED AT 250 WORDS)