PROTECTIVE EFFECT OF VERAPAMIL ON REGIONAL MYOCARDIAL ISCHEMIC-INJURYIN DOG

Ischaemic injury was produced in the dog heart by occluding the left a nterior descending coronary artery just below the second diagonal bran ch for 3 h. Verapamil 5.0 mg/kg was injected intravenously 10 min befo re the occlusion. There was some decrease in ATP and creatine phosphat e levels in the hearts of ''no drug'' animals as compared to sham-oper ated dogs. Verapamil significantly increase the level of these metabol ites. The ATP/ADP ratio decreased from 8.5 +/- 0.60 in hearts from sha m-operated dogs to 3.5 +/- 0.30 in the ''no drug'' group. Verapamil pr etreatment resulted in values of the ATP/ADP ratio which were lower th an, but not significantly different from, those observed in the contro l group. In ischaemic mitochondria the calcium content (Ca++) increase d 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 t he Verapamil group.