| Abstract: | Plasma atrial natriuretic peptide (ANP) was measured during dynamic exercise in 10 patients with coronary heart disease before and after single dose atenolol 50 mg and acebutolol 200 mg, respectively. Systolic blood pressure, heart rate and the rate-pressure product increased during exercise before and after β-blockade, but levels were lower after β-blockade. Plasma ANP levels at rest were unchanged after atenolol, but rose after acebutolol (p<0.01). During exercise plasma ANP increased significantly both before and after β-blockade, but plasma ANP levels were higher after acebutolol at all workloads (p<0.05), whereas plasma ANP levels after atenolol were higher at 125 W exclusively (p<0.05). The augmented ANP levels during exercise after β-blockade probably reflect catecholamine-stimulated ANP release, whereas the elevated plasma ANP levels after acebutolol at rest might be a β-adrenoceptor-mediated ANP release due to the intrinsic sympathomimetic effect of acebutolol. |
