Protective effect of verapamil on regional myocardial ischaemic injury in dog.

Ischaemic injury was produced in the dog heart by occluding the left anterior descending coronary artery just below the second diagonal branch for 3 h. Verapamil 5.0 mg/kg was injected intravenously 10 min before the occlusion. There was some decrease in ATP and creatine phosphate levels in the hearts of "no drug" animals as compared to sham-operated dogs. Verapamil significantly increase the level of these metabolites. The ATP/ADP ratio decreased from 8.5 +/- 0.60 in hearts from sham-operated dogs to 3.5 +/- 0.30 in the "no drug" group. Verapamil pretreatment resulted in values of the ATP/ADP ratio which were lower than, but not significantly different from, those observed in the control group. In ischaemic mitochondria the calcium content (Ca++) increased significantly as compared to the control and the Verapamil group. A significant increase in free fatty acid content in myocardial membrane preparations was also observed as compared to the sham-operated and the Verapamil group.