葡萄糖酸镁对离体大鼠心肌缺血再灌注细胞凋亡的影响

Effects of magnesium gluconate on the apoptosis in myocardial cells of rats with ischemia reperfusion injury in vitro

目的观察葡萄糖酸镁对离体大鼠心肌缺血／再灌注（I／R）细胞凋亡的保护作用及可能机制。方法选用48只雄性SD大鼠随机等分为3组：对照组，I／R组，葡萄糖酸镁组。实验1：每组取8只大鼠，对照组用改良的K—H液持续灌注110min；I／R组用改良的K—H液灌流20min后，停灌30min，再灌注60min；葡萄糖酸镁组改良的K—H液中加入葡萄糖酸镁2．4mmol／L，余同I／R组。检测心肌灌流液中肌酸激酶（CK），乳酸脱氢酶（LDH）含量，心肌组织中Ca^2＋和一氧化氮（NO）含量。实验2：每组其余8只大鼠，实验过程类似实验1，不同点再灌时间120min。实验结束检测心肌细胞凋亡指数。观察实验l、2再灌注20min内心律失常发生情况。结果与I／R组比较，葡萄糖酸镁组心律失常发生率显著下降（P〈0．01）；再灌流出液中CK、LDH含量明显降低（P〈0．01）；心肌组织Ca^2＋和NO含量及细胞凋亡指数明显降低（P〈0．01）。结论葡萄糖酸镁可通过增加NO含量减轻钙超载从而减少凋亡。

Objective To observe the protective effect of magnesium gluconate on myocardial apoptosis by ischemia reperfusion injury in isolated rat hearts, and study the possible mechanism. Methods The hearts of 48 Sprague-Dawely rats were isolated, linked to Langendorff perfusion apparatus, and randomly divided into 3 equal groups（ n = 16 each） ： Control group, isehemia/reperfusion （I/R） group and magnesium gluconate group. 8 rats in each group were perfused. Control group was perfused with modified KH buffer for 110min. I/R group was perfuesd with modified KH buffer for 20 min, then exposed to ischemia for 30 min, and then reperfused with modified KH buffer for 60 min. Magnesium gluconate group was perfumed with modified KH buffer with magnesium gluconate for 20 min, then exposed to ischemia for 30 min and then reperfused with modified KH buffer with magnesium gluconate for 60 min. Lacate dehydrogenase （LDH） and creatine kinase （CK） in the effluent liquid from the heart were measured after reperfusion. The concentration of Ca^2＋ and NO in the left ventricle were determined. The other 8 rats in each group were reperfused for 120 minutes as the method described before. After reperfusion, the myocyte apoptosis was examined by Annexin-V-FITC/PI. After the two experiments the incidence of ventricular arrhythmias during reperfusion was assessed. Results Compared with I/R, magnesium gluconate decreased the incidence of ventricular arrhythmias（ P 〈 0. 01 ）. The contents of CK and LDH in the effluent liquid from the heart in magnesium gluconate group was lower than that of I/R group （ P 〈0. 01 ）. The contents of Ca^2＋ and NO in the left ventricle in magnesium gluconate group was decreased than that of I/R group （ P 〈0. 01 ）. The index of myocyte apoptosis were significantly lower in magnesium gluconate group than that of I/R group （ apoptosis index ：27.79 ± 1.59 vs 33.61 ± 2.10, P〈0. O1 ） . Conclusion Magnesium gluconate has protective effect on myocardial ischemia reperfusion injury in rats. The protective effect may be related to decreasing myocyte apoptosis by increasing the content of NO and relieving calcium overload.