The effect of the vasoselective calcium antagonist felodipine on myocardial necrosis was studied in 14 anesthetized pigs subjected to 45-min occlusion of the left anterior descending coronary artery (LAD) followed by 24-h reperfusion. Felodipine (7 nmol/kg, n = 7), or the corresponding amount of vehicle diluted in 300 ml saline (n = 7) was infused in the great cardiac vein for 30 min beginning 5 min before onset of reperfusion. Regional myocardial function was measured as percentage of systolic segment shortening (%SS) by sonomicrometry. The recovery in ischemic myocardium was significantly already better among felodipine-treated animals after 30-min reperfusion (mean +/- SD = 9.1 +/- 6.1 vs. 0.1 +/- 3.2%, p < 0.05). The improved recovery in the felodipine group persisted throughout the observation period; %SS was 8.5 +/- 5.9% after 24-h reperfusion. No significant improvement was observed in the vehicle group after 24 h (%SS = 2.7 +/- 2.0%, p < 0.05). The area of the infarct was measured by triphenyl tetrazolium chloride staining. When expressed as percentage of the left ventricle, the infarct was smaller in the felodipine group (8.2 +/- 4.0%) than in the vehicle group (14.6 +/- 3.5%; p < 0.01). The corresponding values for infarct size expressed as percentage of the area at risk was 38.6 +/- 18.9% in the felodipine group and 69.8 +/- 6.7% in the vehicle group (p < 0.01). Peak plasma felodipine concentration was reached 30 min after onset of reperfusion (4.9 +/- 1.2 nM).(ABSTRACT TRUNCATED AT 250 WORDS)