Original Article: PDF OnlyWinslow E.; Kelly, M. E.; Law, E. A.Journal of Cardiovascular Pharmacology: July-August 1980 - p 425-434 Free Abstract The antidysrhythmic agent Org 6001 (3.9–31.2 mg/liter) was compared with lignocaine and propranolol (3.6–14.5 and 1.3 mg/liter, respectively) for effects on reperfusion dysrhythmias, coronary effuent potassium content and lactate dehydrogenase (LDH) release in isolated perfused rat hearts. Hearts were perfused using the Langendorff technique, and the epicardial electrocardiogram recorded. The main left coronary artery was ligated for 20 min and reperfused for 15 min. The coronary effluent was collected during 5 min intervals, and samples were analyzed for LDH content. Drug perfusion was started 5 min prior to or 2 min after ligation. All three drugs inhibited the development of reperfusion-induced fibrillation. However, isolated premature systoles were more resistant. None of the drugs inhibited the increase in LDH release evoked by ligation or reperfusion. Propranolol significantly increased LDH release during the first 5 min of occlusion. Changes in coronary effluent potassium were not demonstrable even in control hearts. In conclusion, in the concentrations used, Org 6001, lignocaine, and propranolol did not reduce very early ischemic damage in the isolated rat heart as determined by release of LDH, whereas all three drugs were effective in antagonizing dysrhythmias evoked by reperfusion. © Lippincott-Raven Publishers.