超极化停搏对家猫体外循环时心肌细胞膜脂区域流动性的影响

Effect of hyperpolarized cardiac arrest on regional fluidity of myocardial cell membrane during cardiopulmonary bypass in felines

目的 探讨超极化停搏对猫体外循环（CPB）时心肌细胞膜脂区域流动性的影响。方法 家猫75只，体重3～4kg，随机分为3组（n=25），CPB组：CPB建立后不阻断上腔静脉、下腔静脉和主动脉，仅行CPB 150min；去极化停搏组：主动脉阻断60min，再灌注60min，心脏停搏液使用高钾St Thomas液；超极化停搏组：心脏停搏液使用含吡那地尔的低钾St Thomas液，余处理与去极化停搏组相同。应用自旋标记-电子自旋共振技术测定CPB时心肌细胞膜脂区域流动性。结果 与CPB组比较，去极化停搏组主动脉阻断30min后心肌细胞膜脂S和τc均升高，超极化停搏组主动脉阻断60min后心肌细胞膜脂S和τc均升高（P〈0．01）；与去极化停搏组比较，超极化停搏组主动脉阻断30min后心肌细胞膜脂S和τc均降低（P〈0．01）。结论与去极化停搏相比，超极化停搏能够更好地维持家猫CPB时心肌细胞膜脂的区域流动性。

Objeetive To investigate the effect of hyperpolarized cardiac arrest on regional fluidity of myocardial cell membrane during cardiopulmonary bypass （CPB） in felines. Methods Seventy-five felines of both sexes weighing 3-4 kg were randomized into 3 groups （n = 25 each） ： group Ⅰ CPB control; group Ⅱ depolarized cardiac arrest and group Ⅲ hyperpolarized cardiac arrest. The animals were anesthetized with intramuscular pentobarbital 20-30 mg/kg, tracheostomized and mechanically ventilated. An in vivo CPB model was used. In CPB control group CPB was instituted without aortic cross-clamping （ACC）. Cardioplegia was induced with St Thomas solution containing KCl 16 mmol/L in depolarized cardiac arrest group and with hypokalemic St Thomas solution containing pinacidil 50 mmol/L in hyperpolarized cardiac arrest group respectively： Five animals were killed before ACC, at 30 and 60 rain after ACC and 30 and 60 rain of reperfusion respectively and myocardial specimens were obtained from left ventricle. An electron spin resonance （ESR） technique was employed to monitor membrane regional fluidity of cardiomyocyte. Results S and τc of myocardial cell membrane was significantly increased at 30 rain after ACC in depolarized cardiac arrest group and at 60 rain after ACC in hyperpolarized cardiac arrest group as compared with CPB control group. S and τc of myocardial cell membrane was significantly decreased at 30 rain after ACC in hyperpolarized cardiac arrest group as compared with depolarized cardiac arrest group. Conehtsion The regional fluidity of myocardial cell membrane is better maintained in hyperpolarized cardiac arrest than depolarized cardiac arrest.