A structural analogue of gamma-butyrobetaine 3-(2,2,2-trimethylhydrazine)propionate (THP) administered orally in doses of 50 and 150 mg/kg for 10 days prevented isoproterenol-induced increase of the activity of the hepatic isoform of lactate dehydrogenase in the rat blood serum and in a dose of 150 mg/kg prevented an increase of creatine phosphokinase activity. Against a background of the course administration of THP isoproterenol failed to cause the accumulation of acyl-insoluble acylcarnitine in the myocardium. In this case a dose-dependent decrease of free carnitine concentration and accumulation of fatty acids in the myocardium were noted. The cardioprotective effect of THP manifested itself in prevention of a decrease of ATP and ADP concentrations, accumulation of AMP and a reduction of energy charge under the influence of isoproterenol. The ability of THP to decrease the intracellular concentration of free carnitine and to depress as a result carnitine-dependent oxidation of free fatty acids may underlie the anti-ischemic effect of THP.