缺血预处理及低温对幼兔心肌缺血/再灌注损伤的影响

EFFECTS OF ISCHEMIC PRECONDITIONING ON THE HYPOTHERMIC ISCHEMIA/REPERFUSION INJU RY OF IMMATURE RABBIT HEARTS

目的 :探讨缺血预处理 (ischemicpreconditioning ,IP)及低温对幼兔心脏缺血 /再灌注损伤的影响。 方法 :采用Langendorff离体心脏灌注模型 ,取 3～ 4周龄幼兔心脏 ,分别给予不同次数的IP后使其在 2 0℃低温下缺血或给予同样次数的IP后使其分别在不同低温下缺血。常温再灌注 30min。记录心脏缺血 /再灌注前后左心室功能指标 ,测定再灌注末心肌组织中ATP和丙二醛 (MDA)含量 ,超氧化物歧化酶 (SOD)及Ca2 + ATP酶的活性。结果 :再灌注末 ,IP2组左心室各功能指标的恢复率及心肌组织的ATP含量及Ca2 + ATP酶的活性均显著高于Con组和IP3组 ;SIP1、SIP2组的左心室各功能指标的恢复率及心肌组织的ATP含量均分别显著高于SCon1组和SCon2组 ,其心肌组织MDA含量亦分别低于SCon1组和SCon2组。结论 :IP可减轻低温缺血的幼兔心肌缺血 /再灌注损伤 ,其效应与IP的次数和低温程度有关。

Aim: To study effects of ischemic preconditioning on the hypothermic ischemia/reperfusion injury of immature rabbit hearts. Methods: The isolated immature rabbit (3～4 weeks) hearts were perfused on Langendorff a pparatus. After 30 min perfusing with 37℃ K-H perfusate, the hearts in part on e were yielded 0, 1, 2 or 3 times of IP respectively before 120 min ischemia at 20℃ hypothermia, and the hearts in part two were yielded 0 or 2 times of IP bef ore being arrested by infusion of St.Thomas Ⅱ crystalloid cardioplegic solution , then the arrested hearts were yielded ischemia for 30, 90 or 120 min at 32℃, 25℃ and 20℃ hypothermia respectively.Then all the hearts were reperfused for 3 0 min at 37℃ normothermia. Heart rate (HR), left ventricular developed pressure (LVDP), ±dp/dt max were recorded at baseline, preischemia and 1, 3, 5, 10 , 20, 30 min after reperfusion. Also contents of ATP and MDA and activity of SOD and Ca 2+ -ATPase of myocardium were measured. Results: At th e end of reperfusion, the recovery rate of left ventricular function in IP2 grou p were significantly higher than that of control group and IP3 group(P<0.01 ,P< 0.05 ),also the IP2 group showed a higher content of ATP and activit y of Ca 2+ -ATPase than control group and IP3 group(P<0.01,P< 0. 05 ). When the ischemic hearts were at different hypothermia accompanied with CCS, the recovery rate of left ventricular function and contents of ATP in SIP1 and SIP2 group were significantly higher than that of SCon 1 group and SCon 2 gr oup respectively(P<0.01,P<0.05),the contents of MDA in the two IP gr ou ps were lower than that of the two control groups. Conclusion: IP ca n attenuate the hypothermic ischemia/reperfusion injury of immature rabbit heart s, the cardioprotective effects are dependent on the mode of IP and the possible mechanisms may involve the following aspects: decrease the consumption of ATP, inhibit lipid peroxidation and maintain the activity of Ca 2+ -ATPase of ca rdiac myocyte.