七氟醚预处理对大鼠心肌缺血再灌注时缝隙连接蛋白43的影响

Effects of sevoflurane preconditioning on myocardial connexin 43 during myocardial ischemia-reperfusion in rats

目的评价七氟醚预处理对大鼠心肌缺血再灌注时缝隙连接蛋白43的影响。方法健康成年雄性Wistar大鼠，体重220～250g，采用改良Langendorff灌注装置制备离体心脏灌注模型。取离体心脏模型16个，采用随机数字表法，将其随机分为2组（n=8）：缺血再灌注组（I／R组）和七氟醚预处理组（sP组）。平衡灌注30min时，I／R组继续灌注K-H液20min；SP组将2．4％七氟醚持续吹入K—H液中，用预充2．4％七氟醚的K-H液持续灌注15min，然后用K—H液洗脱5min。之后两组均行全心缺血40min，再灌注60min。分别于平衡灌注末、缺血前即刻、再灌注30和60min时，记录HR、左室发展压（LVDP）、左心室内压最大上升速率（＋dp／dtmax）及左心室内压最大下降速率（-dp／dtmax）。于再灌注60min时，取部分心尖组织，观察心肌病理学改变；取左室部分心肌，观察缝隙连接蛋白43的分布情况，测定缝隙连接蛋白43的表达。结果与平衡灌注末比较，I／R组和sP组缺血前即刻＋dp／dtmax和-dp／dtmax降低，再灌注30和60min时HR、LVDP、＋dp／dtmax和-dp／dtmax降低（P〈0．01）；与缺血前即刻比较，I／R组和sP组再灌注30和60min时HR、LVDP、＋dp／dtmax和-dp／dtmax降低（P〈0．05或0．01）；与I／R组比较，sP组缺血前即刻HR、LVDP、＋dp／dtmax和-dp／dtmax降低，再灌注30和60min时HR、LVDP、＋dp／dtmax和-dp／dtmax升高（P〈0．01），病理学损伤减轻。缝隙连接蛋白43I／R组分布不均，闰盘处少见；SP组分布规律呈条带状，主要位于闰盘处。两组缝隙连接蛋白43表达比较差异无统计学意义（P〉0．05）。结论七氟醚预处理减轻大鼠心肌缺血再灌注损伤的机制可能与抑制缝隙连接蛋白43的再分布有关，而与缝隙连接蛋白43的表达无关。

Objective To investigate the effects of sevoflurane preconditioning on myocardial connexin 43 （Cx43） during myocardial ischemiareperfusion （I/R） in rats. Methods Male adult Wistar rats weighing 220-250 g were anesthetized with intraperitoneal pentobarbital 40 mg/kg and heparin 500 IU/kg. Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95%O2-5%CO2 at 37℃ for 30 min. Sixteen isolated rat hearts were randomly assigned into 2 groups （ n = 8 each） ： I/R group and sevoflurane precon- ditioning group （group SP）. At 30 rain of equilibration, group I/R received perfusion for another 20 min, the hear- ts were purfused with K-H solution saturated with 2.4% sevoflurane for 15 min followed by 5 min washout with K-H solution in group SP. Then all the hearts underwent 40 min of ischemia followed by 60 min of reperfusion. HR, left ventrieular developed pressure （LVDP）, ＋ dp/dtm~ and - dp/dtm= were reeorded at the end of equilibration, immediately before ischemia and at 30 and 60 min of reperfusion. Myocardial tissues were obtained from apex for microscopic examination and from left ventricle for observation of distribution of Cx43 and determination of Cx43 expression. Results Compared with the baseline value at the end of equilibration, ＋ dp/dtmax and - dp/dtmax immediately before ischemia and HR, LVDP, ＋ dp/dtm= and - dp/dt,= at 30 and 60 min of reperfusion were signifi- cautlydecreased in groups I/R and SP （P 〈 0.01 ）. Compared with that immediately before ischemia, HR, LVDP, ＋ dp/dtmax and - dp/dt,= were significantly decreased at 30 and 60 min of reperfusion in groups I/R and SP （ P 〈 0.05 or 0.01）. Compared with group I/R, HR, LVDP, ＋ dp/dtm= and - dp/dt,= were significantly decreased immediately before ischemia, HR, LVDP, ＋ dp/dtmax and -dp/dt,= were significantly increased at 30 and 60 min of reperfusion （ P 〈 0.01 ）, and pathological injury was attenuated in group I/R. Myocardial Cx43 was unevenly distributed in group I/R, while evenly distributed in group SP. There was no significant difference in Cx43 expression between the two groups. Conclusion The mechanism by which sevoflurane preconditioning protects myocardium against I/R injury may be related to redistribution of Cx43, but not Cx43 expression.