EFFECT OF LONG-TERM ORAL NISOLDIPINE ON INFARCT SIZE AND COLLATERAL DEVELOPMENT IN PIGS UNDERGOING GRADUAL OCCLUSION OF THE LEFT CIRCUMFLEX ARTERY

We examined the effects of nisoldipine on infarct size and collateral development in pigs, whose coronary circulation is similar to that of humans, using an experimental protocol reproducing as closely as possible the usual clinical setting. Fifteen pigs undergoing left circumflex Ameroid-occlusion were randomized into a control group (n = 8) and a group (n = 7) treated with oral nisoldipine 0.03 mg/kg every 6 h for 1 month starting on the second postoperative day. Infarct size (tetrazolium red) was 37.2 ± 9.2% of the circumflex distribution in the control group and 10 ± 3.2% in the treated group (p < 0.01). Endocardial and transmural blood flows (microspheres) in the circumflex distribution were significantly higher (p < 0.05) in the treated group (control endocardial 1.25 ± 0.1 ml/g/min, treated endocardial 1.77 ± 0.26 ml/ g/min; control transmural 1.39 ± 0.08 ml/g/min; treated transmural 1.78 ± 0.23 ml/g/min). Epicardial flow and the ratio of subendocardial to subepicardial blood flow (endo/ epi) were nonsignificantly higher in treated pigs. No differences were observed in heart rate (HR) and aortic pressure (AP). We conclude that in pigs undergiong left circumflex Ameroid-occlusion, long-term oral nisoldipine reduces infarct size and enhances collateral circulation to the ischemic myocardium. © 1990 Raven Press, Ltd., New York.