Changes in pulmonary hemodynamics induced by experimental myocardial ischemia in nitroglycerin- or acetylcholine-treated rabbits.

The responses of cardiovascular parameters to left-ventricular myocardial ischemia induced under control conditions and after administration of nitroglycerin or acetylcholine were examined in rabbits. In nitroglycerine-treated rabbits, experimental myocardial ischemia produced less pronounced depressor BP shifts in the pulmonary artery than those produced by ischemia in controls (prior to pharmacological treatment) or by experimental ischemia provoked after acetylcholine infusion. Control and experimental ischemia (provoked after nitroglycerin or acetylcholine administration) induced the same drop in pulmonary blood fl ow accompanied with insignificant changes in vascular pulmonary resistance. Experimental ischemia produced smaller pressure increase in left atrium of nitroglycerine-treated rabbits (evidencing a smaller drop in left ventricular contractility) than the control ischemia performed prior to pharmacological treatment, or the experimental ischemia in acetylcholine-treated rabbits, which attested to protective effect of nitroglycerin against ischemia.