The cardioprotective effect of verapamil.

1. Prolonged periods of normothermic ischaemia and reperfusion produce changes in the ultrastructure of the myocardium. Experiments were undertaken to establish whether the prophylactic use of verapamil provided protection. 2. Rabbits were pretreated with verapamil (2 mg/kg twice daily s.c. for 4-5 days). The hearts were isolated, perfused aerobically, made ischaemic or made ischaemic and then reperfused. The hearts were then perfusion fixed and sectioned for electronmicroscopy. 3. Verapamil pretreatment decreased the ultrastructural damage caused by ischaemia and reperfusion.