Nifedipine limits infarct size for 24 hours in closed chest coronary embolized dogs

We studied the ability of nifedipine, a calcium antagonist, to limit infarct size in the closed chest, coronary embolized dog. Immediately after embolization 141Ce labelled microspheres were administered into the left ventricle. Myocardium not receiving microspheres was considered to be the region at risk. The nifedipine group (10 dogs) received a bolus (16 micrograms/kg i.v. over 8 minutes as a loading dose) followed by continuous infusion (1,000 micrograms/24 hours) 10 min after embolization. The control group (9 dogs) received an equal volume of saline. Twenty-four hours after embolization the dogs were sacrificed, the heart sectioned into 4-mm slices and the slices were stained with tetrazolium to reveal the infarct. The region at risk was determined by autoradiography of the microspheres in the heart slices. Infarct and risk zone volume were determined by planimetric methods. The nifedipine group had a significantly smaller infarct volume to risk zone volume ratio than the control group (38.7 +/- 4.7% vs. 79.5 +/- 4.3%, p less than 0.001). We conclude that nifedipine produces a sustained limitation of infarct size following permanent occlusion of a dog's coronary artery.