Short-acting calcium antagonist clevidipine protects against reperfusion injury via local nitric oxide-related mechanisms in the jeopardised myocardium

Background: Calcium antagonists may, in addition to their classical actions . release nitric oxide (NO) from coronary arteries. The aim of this study w as to elucidate the possible interaction between the cardioprotective effec t of a short-acting calcium antagonist and NO during myocardial ischaemia a nd reperfusion. Methods: Anaesthetised pigs were subjected to 45 min ligati on of the left anterior descending coronary artery (LAD) followed by 4 h of reperfusion. Five groups were given vehicle (n=9), clevidipine (n=8), the NO synthase inhibitor L-NMMA (n=6), clevidipine in combination with L-NMMA (n=6) or clevidipine in combination with L-NMMA and NO precursor L-arginine (n=6) into the LAD during the last 10 min of ischaemia and the first 5 min of reperfusion. Results: There were no significant differences in LAD bloo d flow, mean arterial pressure, rate-pressure product or dP/dt between the groups before ischaemia or during reperfusion. The infarct size (IS) was 86 +/-2% of the area at risk in the vehicle group, Clevidipine reduced the IS to 59+/-3% (P<0.001). When clevidipine was administered together with L-NMM A, the protective effect of clevidipine was abolished (IS, 87+/-3%; P<0.001 vs. clevidipine), whereas addition of L-arginine restored its cardioprotec tive effect (IS 60+/-3%; P<0.001 vs, vehicle). L-NMMA did not affect IS per se (88+/-5%). Endothelium-dependent coronary vasodilation induced by subst ance P was significantly larger in the clevidipine group than in the other groups. Conclusion: Local administration of a calcium antagonist during the late ischaemia and early reperfusion reduces IS and preserves coronary end othelial function. The cardioprotective effect of clevidipine is suggested to be dependent on maintained local bioavailability of NO. (C) 2001 Elsevie r Science B.V. All rights reserved.