Exercise‐induced myocardial ischemia in pigs: Cardiovascular actions of nisoldipine with or without β‐adrenoceptor blockade

We evaluated the effects of oral nisoldipine with or without propranolol on exercise‐induced myocardial ischemia in conscious pigs with a coronary artery stenosis. Treadmill‐running up to 4 km/hr increased cardiac output (90%), heart rate (90%), maxLVdP/dt (80%), left ventricular systolic (15%) and end‐diastolic (13±3 mmHg) blood pressures, while systolic wall thickening (SWT) of the poststenotic left ventricular myocardium was reduced from 29%±8% to 19%±6%. Nisoldipine neither affected the systemic hemodynamic profile during exercise nor the exercise‐induced reductions in SWT. Propranolol attenuated both the positive chronotropic and inotropic effects and the deterioration of wall function caused by the treadmill exercise. Combined treatment with the two drugs resulted in a cardiovascular profile similar to propranolol during exercise, but the loss of wall function was now completely prevented. We conclude that, unlike propranolol, nisoldipine alone was not effective against the exercise‐induced myocardial ischemia but, in combination with β‐adrenoceptor antagonists, nisoldipine may further decrease the exercise‐induced reductions in SWT of the poststenotic myocardium.