Prevention of adrenaline-induced metabolic systemic and myocardial alterations by the beta-blocking agent metipranolol in the dog.

We investigated the effectiveness of the beta-blocking agent metipranolol in preventing detrimental systemic and myocardial alterations induced in healthy dogs by adrenaline (AD) infused at a rate which mimics spontaneous secretion after coronary occlusion. Metipranolol (0.3 mg/kg) was infused intravenously concurrently with AD (1.2 micrograms/kg/min) for 4 h and blood values of free fatty acids (FFA) and triiodothyronine(T3) were measured initially, after 2 and 4 h of infusion and compared with those obtained in dogs infused with AD alone and with saline. Metipranolol suppressed a rise in free fatty acid, reversed AD-induced histoenzymatic changes in succinic dehydrogenase and ATPase activity and considerably inhibited the development of mitochondrial alterations detected in dogs infused with AD alone. A tendency to attenuate AD-induced fall in serum T3 was also detected in metipranolol-treated dogs. Results suggest that this drug might be of value in preventing consequences of increased adrenergic activity in the acute stage of myocardial infarction.