Coronary artery ligation in anesthetized rats as a method for the production of experimental dysrhythmias and for the determination of infarct size.

Coronary artery ligation in anesthetized rats was assessed as a method for the production of experimental dysrhythmias and for the determination of infarct size. Following occlusion of the left main coronary artery, very marked ventricular dysrhythmias occurred in two distinct phases, an early and a late phase, at 0-30 minutes and at 1 1/2--4 hours after ligation respectively. Infarct size was measured at 4 hours after ligation using nitroblue tetrazolium to stain for the depletion of two cytoplasmic enzymes, lactate dehydrogenase and NADPH diaphorase. In this model, lignocaine (10 mg/kg plus an infusion of 5 mg/kg/hr) and ORG 6001 (10 mg/kg plus an infusion of 2.5 mg/kg/hr) had marked antidysrhythmic activity but neither drug influenced infarct size. The model, because of its simplicity, reproducibility, and low cost, should be useful for the screening of potential antidysrhythmic agents and may also be used to determine infarct size following coronary artery ligation.