[Does the calcium antagonist verapamil protect from myocardial damage during tocolysis with beta-sympathicomimetics?...

Under general anaesthesia nine mongrel dogs were first injected with fenoteral 0.06 mg/kg/per minute and later with fenoteral 0.06 mg/kg/per minute and verapamil 2 mg/kg/per minute. A microtip manometer was placed into the left ventricle and cardiac pressures continously monitored. The resulting pressure curves were used in micro-computer to calculate the cardiac pressure parameters including the inotropic measurements and the myocardical oxygen consumption. The intravenous infusion of the beta-mimetic fenoterol resulted in marked increase of the cardiac rate and contractility as measured in the different measurement of the ionotrophy. A corresponding increase of the myocardical oxygen consumption was found. The addition of the calcium antagonist verapamil did have no influence of the measured parameters. A protective effect of the calcium antagonist on the myocaridium was excluded in the animal experiment. A protective effect during tocolysis with beta-sympathicomimetics cannot be expected because of the expected low serum concentrations.