Nifedipine on cardiovascular leukotriene D4 actions in the anaesthetized dog

Open-chest dogs were used to study the effects of intracoronary leukotriene (LTD4; 0.5 microgram/kg) on haemodynamics, coronary blood flow in the left circumflex artery and coronary resistance in the absence or presence of nifedipine (10 micrograms/kg, i.v.). LTD4 increased ventricular filling pressure by 133% (P less than 0.001), the S-T segments and coronary resistance by 490% (P less than 0.001) and abolished coronary flow for 3 min. Nifedipine pretreatment inhibited the cessation of coronary flow. No change in filling pressure and no ischemia signs in the peripheral ECG were noted. However, nifedipine did not inhibit the LTD4-induced decrease in left ventricular dP/dtmax. Haemodynamic LTD4 actions thus could be partially reversed by i.v. nifedipine, suggesting that leukotriene effects on the coronary and peripheral circulation are mediated by calcium release.