Protective effects of befunolol on hypoxic respiration-induced alterations in myocardial energy metabolism of rats.

The present study was undertaken to elucidate beta-adrenoceptor blocking effects of befunolol (BFE 60, CAS 39543-79-8) on changes in the myocardial metabolites induced by hypoxic respiration. When rats were subjected to hypoxic respiration, a significant increase in heart rate (about 13% increase) and a slight decline in mean aortic blood pressure (about 12% decrease) were observed at 1 min and 6 min after the onset of hypoxic respiration. The hypoxic respiration also elicited decreases in the myocardial ATP and creatine phosphate levels (each 18% decrease) and increases in the myocardial lactate (13% increase) and cyclic-AMP (20% increase) levels. In contrast, these changes were never observed throughout hypoxic respiration when rats had been treated with both reserpine and alpha-methyl-p-tyrosine methylester 20 to 22 h before experiment, suggesting that these metabolic alterations are mediated through beta-adrenoceptor stimulation. These hypoxic respiration-induced hemodynamic and metabolic changes were found to be suppressed by treatment with 1 and 10 micrograms/kg befunolol or 10 micrograms/kg propranolol to an appreciable degree. The results demonstrate protective action of befunolol, like propranolol, on hypoxia-induced changes in the myocardial energy metabolism.