Subacute effects of propranolol and B 24/76 on isoproterenol-induced rat heart hypertrophy in correlation with blood pressure.

We compared the potential beta-receptor blocker, B 24/76 i.e. 1-(2,4-dichlorophenoxy)-3[2-3,4-dimethoxyphenyl)ethanolamino]-prop an-2-ol, which is characterized by beta 1-adrenoceptor blocking and beta 2-adrenoceptor stimulating properties with propranolol. The studies were performed using an experimental model of isoproterenol-induced heart hypertrophy in rats. A correlation of the blood pressure was neither found in the development nor in the attempt to suppress the development of heart hypertrophy with the two beta-receptor blockers. Both beta-blockers influenced the development of hypertrophy to a different, but not reproducible extent. It was possible to suppress the increased ornithine decarboxylase activity with both beta-blockers in hypertrophied hearts, but there was no effect on the heart mass. Neither propranolol nor B 24/76 could stop the changes in the characteristic myosin isoenzyme pattern of the hypertrophied rat heart. Thus, the investigations did not provide any evidence that the beta-receptor blockers propranolol and B 24/76 have the potency to prevent isoproterenol from producing heart hypertrophy.