Abstracts for Oral and Poster Presentations

The purpose of this study is to investigate the effectiveness of pinacidil, an opener of ATP-sensitive K+ channels, in protecting myocardium of immature rabbit hearts from ischemic reperfusion injury. Methods: On Langendorff apparatus the hearts underwent 30 minutes of global normothermic ischemia followed by 30 minutes of reperfusion. 52 isolated hearts of 3–4 weeks old immature rabbits were divided into four groups randomly. During ischemia, three different cardioplegic solutions were administered intermittently by infusion every 15 minutes (20–25 ml every time) Group I control (n=13),; Group II: K-H solution with potassium (16 mmol/L) (n=13) ; Group III: K-H solution with potassium (16 mmol/L) and pinacidil (50 m mol/L) (n=13); Group IV: K-H solution with potassium (16 mmol/L), pinacidil(50 m mol/L) and glibenclamide (10 m mol/L) (n=13). The pre and postischemic myocardial function were assessed by the percentage recovery of left ventricular developed pressure (LVDP), left ventricular end-diastolic pressure (LVEDP), both positive and negative peak first derivative of left ventricular pressures(± dp/ptmax), coronary flow(CF), CK, LDH, AST in coronary sinus venous effluent and by myocardial ultrastructural changes. Results: Before myocardial ischemia, there were no significant difference in all above mentioned parameters in four groups. Postischemic recovery of LVDP, LVEDP, ± dp/dtmax, CF, the level of CK, LDH, AST and myocardial ultrastructural changes were better in group III than that in three other groups.