Alprazolam decreases isoproterenol induced myocardial damage in the rat.

Myocardial trauma and damage were induced by two doses of isoproterenol 40 mg.kg-1 in rats. Isoproterenol injections alone caused the expected cardiotoxicity. Two doses of alprazolam 0.5 mg.kg-1 decreased the severity of electrocardiographic changes after isoproterenol injection and the amount of myocardial tissue damage. The frequency of ischaemic ST-T changes, flat or inverted T waves, Q wave appearance, and heart block was significantly reduced in the alprazolam group. The alprazolam treated group had a significantly smaller proportion of infarcted tissue in the ventricular section (2.3%) and in the apical sections (1.8%) than the vehicle injected rats (6.5% and 14.7% respectively). There was no difference in wet heart weight or in heart rate between the alprazolam group and the control group. These results show that alprazolam has a cardioprotective effect in rats treated with cardiac damaging doses of isoproterenol.