EFFECT OF ISOFLURANE ON EPINEPHRINE-INDUCED ARRHYTHMIAS IN ISCHEMIC-REPERFUSED DOG HEARTS

Although isoflurane protects the myocardium and facilitates functional recovery after ischemia and reperfusion, its mechanism of action is s till unclear. We hypothesized that isoflurane maintains intracellular Ca2+ homeostasis, thus attenuating epinephrine-induced arrhythmogenici ty in in vivo models of myocardial ischemia and reperfusion. Adult mon grel dogs, anesthetized with urethane and chloralose, underwent 15 min utes of left anterior descending coronary artery occlusion followed by reperfusion. In addition to a sham group (without occlusion, n = 5) a nd a control group (with occlusion, n = 7), a third group (n = 5) rece ived 1.5% isoflurane before ischemia was induced; a fourth (n = 7), is oflurane after reperfusion; and a fifth (n = 5), isoflurane and verapa mil (100 mu g/kg) after reperfusion. Isoflurane administered before is chemia increased the arrhythmogenic dose of epinephrine (ADE), but had no effect on ADE when administered after reperfusion. The addition of verapamil further increased the ADE. These results indicate that isof lurane has a cardioprotective effect during ischemia and reperfusion b y, at least in part, the reduction of Ca2+ influx.