二氮嗪对长时程低温保存移植鼠心ATP酶的影响及意义

Effects and influences of diazoxide on ATPase of long-term preservation heart in orthotopic cardio-transplantation of rats

目的观察线粒体ATP敏感性钾离子通道开放剂二氮嗪(Diazoxide,DE)对移植鼠心心肌细胞膜Na+-K+-ATPase和肌浆网Ca2+-ATPase活性的影响,并探索DE处理后Celsior液对长时程低温保存鼠心的作用。方法SD雄性大鼠192只随机分为4组,即A组(单纯Celsior液保存5h)、B组(30μmol/L DE+Celsior液保存5h)、C组(30μmol/L DE+Celsior液保存8h)、D组(30μmol/L DE+Celsior液保存10h)。利用改良Heron法大鼠颈部异位心脏移植模型,供体鼠心按各组要求保存后移植于受体,观察移植心脏30s内复跳率、心率;检测心肌细胞膜Na+-K+-ATPase和肌浆网Ca2+-ATPase活性;观察心肌超微结构。结果(1)复跳率和心率:心脏移植术后30s复跳率各组均无显著性差异;B组、C组心率明显较A组、D组快,A组、D组心率差异无显著性意义。(2)两酶活性测定:B、C、D3组心肌细胞膜Na+-K+-ATPase活性随着保存时间的延长呈显著递减性降低,但仍高于A组,仅D组与A组差别无显著性意义;B组、C组肌浆网Ca2+-ATPase活性显著高于D组、A组,D组与A组差别无统计学意义。(3)心肌超微结构:各组心肌结构保护均较好,肌纤维排列整齐,肌节清,线粒体肿胀不明显;B、C、D3组线粒体嵴结构较为清楚。(4)D组和A组各指标差别均无显著性意义。结论移植鼠心在长时程冷缺血期间,DE对心肌组织ATP酶活性有较好的保护作用,此作用随着保存时间的延长而减弱。且DE处理后Celsior液冷保存鼠心10h仍与国际公认的Celsior液安全冷保存时间5h效果相当。

Objective To study whether diazoxide in the cardioplegia solution could improve the activities of sarcolemmal Na+-K+-ATPase and sarcoplasmic reticulum(SR)Ca2+-ATPase during different overtime hypothermic preservations of the rat's heart and to investigate the heart transplantation efficiency. Methods The modified Heron's technique for heterotopic cervical cardio-transplantation in rats with cuff vessel anastomosis was used. A total of 192 donor hearts were randomly stored in 4°C Celsior cardioplegia solution(group A) or Celsior solution containing diazoxide (30 μmol/L) for 5 (group B), 8 (group C) or 10 (group D) hours. The restorative rate of heartbeat and heart rate were recorded, the activities of sarcolemmal Na+-K+-ATPase and SRCa2+-ATPase were measured, and the myocardial ultrastructure was determined. Results No significant difference in the restorative rate of heartbeat was found among the 3 groups and the heart rate was better in groups B and C than that in groups A and D. Diazoxide improved the activities of sarcolemmal Na+-K+-ATPase and SRCa2+-ATPase in groups B and C. The level of sarcolemmal Na+-K+-ATPase in groups B, C, and D was significantly decreased with the preservative time prolonged, but were still higher than that in group A. No significant differences in the two ATPase were noted in group A and D. No observable histological changes were noted in any group. The protection of myocardial fibers and mitochondrial structure in group B were the best. No significant difference in any index was found in groups A and D. Conclusions Diazoxide could improve the activities of sarcolemmal Na+-K+-ATPase and SRCa2+-ATPase in the cardioplegic period and the effect was decreased gradually with the time prolonged. Celsior solution with diazoxide could safely and effectively preserve the heart for 10 hours.