Myocardial protective effect of pinacidil pretreatment on isolated rabbit heart arrest induced with high potassium crystalloid cardioplegia at different temperatures

    YANG Shiª²Guang, YU Tian, YU Zhiª²Hao, LIU Xingª²Kui, YE Ying

    Department of Anesthesiology, Longgang Central Hospital , Shenzhen 518116, China

    ¡¾Abstract¡¿ AIM: To evaluate the myocardial protective effect of pinacidil pretreatment on isolated rabbit hearts arrested with high potassium crystalloid cardioplegic solution at different temperatures. METHODS: Twentyª²four rabbit hearts were randomly divided into 3 groups: control group (group C, hypothermic hyperkalemic cardiac cardioplegia) and pinacidil pretreatment groups [warm pretreatment group (WP) and cold pretreatment group (CP), i.e., normothermic pretreatment and hypothermic pretreatment respectively]. Isolated rabbit hearts (group C) were perfused with oxygenated Krebsª²Henseleits solution (Kª²H) by Langendorff apparatus for 10 min, followed with the standard 4¡æ St. Thomas solution (K+16 mmol/L at 37¡æ) cardioplegia. In group WP and group CP, when the hearts were perfused with Kª²H for 10 min, Kª²H solution containing pinacidil 10 ¦Ìmol/L (37¡æ in group WP, 4¡æ in group CP) pretreatment was carried out before the standard St. Thomas (37¡æ in group WP, 4¡æ in group CP) was perfused. The hearts were subjected to 45 min ischemia (group C and group CP, 26-28¡æ; group WP, 36-38¡æ) and followed by 20 min reperfusion with 37¡æ Kª²H solution. The time of heart arrest and rebeating, heart rate, heart rhythm, left ventricle pressure, left ventricle pressure (LVP), myocardial adenylate and malondialdehyde (MDA) level were analyzed respectively. The myocardial structure of microscopic structure was determined. RESULTS: The time of heart arresting was not different in the 3 groups. The rate of rebeating after aortic unclamping was faster in pretreatment groups than that in group C (P<0.05), but it was significant different between the 2 pretreatment groups. Recoveries of left ventricle pressure and LVP were more rapid in group CP than those in group WP or group C (P<0.05). The recovery of LVP was better in group WP than that in group C (P<0.05). The levels of ATP, TAN and EC were the highest in group CP, the lowest levels in group C, and inª²between in group WP. Myocardial microscope structure was the best in the group CP, then in group WP and group C in a descending order. MDA content was not significantly different in the 3 groups. CONCLUSION: Pinacidil pretreatment may remarkably enhance the myocardial protection against ischemia/reperfusion injury on the isolated hearts arrested with high potassium crystalloid and has a better protective effect on hypothermic cardiac cardioplegia. ......