The role of prostaglandins in the antiarrhythmic effect of ischemic preconditioning

The role of prostaglandins in the antiarrhythmic effect of ischemic precond itioning (IP) was investigated in pentobarbital-anesthetized rats. In 5 unp reconditioned control rats, 30 min of occlusion of the left coronary artery elicited ventricular tachycardia (VT) and fibrillation (VF), with an avera ge duration of VT and VF of 51 +/- 6 and 43 +/- 4 s, respectively. Frequent ventricular premature beats (VPBs; average 1,249 +/- 145) were also docume nted in these animals. Thirty minutes of reperfusion after the prolonged co ronary occlusion in these animals caused more severe arrhythmias, including irreversible VF. In animals pretreated with IP (n = 5), which was achieved by 3 cycles of 3 min of occlusion followed by 6 min of reperfusion, 30 min of coronary artery occlusion caused neither VT nor VF, but occasional VPBs (average 2 +/- 1, p < 0.001 vs. control). Only occasional VPBs were observ ed during 30 min of reperfusion in this group. In animals pretreated with i ndomethacin (1 mg/kg i.v., n = 5) followed by IP, prolonged ischemia and re perfusion led to frequent VPBs but no VT or VF. The average number of VPBs during ischemia and reperfusion in this indomethacin-treated group was less than that of the controls but greater than the IP-only group (p < 0.01). I n conclusion, prostaglandins appear to play a role in the protective effect of IP against VPBs during acute ischemia and reperfusion. Copyright (C) 20 01 National Science Council, ROC and S. Karger AG, Basel.