beta-blockade, atrial natriuretic peptide and exercise

Changes in the release of atrial natriuretic peptide (ANP) and vasopressin (VP) may contribute to the final outcome of beta-adrenoceptor blocking therapy. Therefore, we administered 2 hours before a bicycle exercise test (a 30-minute exercise with 100 W work load) in a randomized, double-blind, placebo-controlled crossover study orally 50 mg atenolol, 80 mg propranolol or 10 mg pindolol to 15 healthy volunteers. Hormone release and sympathoadrenal activation were estimated by measuring plasma ANP-, VP-, adrenaline and noradrenaline concentrations. beta-blockade and -antagonism were estimated by measuring the reduction of exercise-induced tachycardia and the extent to which the drugs occupied rabbit lung beta 1- and rat reticulocyte beta 2-adrenoceptors in the circulating plasma. We noticed clear differences in the animal beta 1- and beta 2-receptor occupancy between these agents. The agents and placebo during the exercise augmented plasma ANP level similarly, on average by 34-72%. Pindolol administration enhanced the decline of plasma ANP level after exercise (ANCOVA rep meas, pindolol vs placebo, p < 0.05). Although pindolol increased the mean plasma VP level by 25% (ANCOVA rep meas for the increase, pindolol vs placebo, p < 0.05), drug effects on plasma VP-level were generally negligible. In conclusion, in healthy volunteers beta 1- and beta 2-antagonism by pindolol, atenolol and propranolol do not markedly potentiate plasma ANP- and VP-responses to physical exercise. The responses are, however, slightly influenced presumably by the beta-agonist activity of pindolol.