Li Jia, Wu Feng, Zhang Haifeng, Fu Feng, Ji Lele, Dong Ling, Li Qiuxia, Liu Wenchong, Zhang Yuan, Lv Anlin, Wang Haichang, Ren Jun, Gao Feng
Department of Physiology and Cardiology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
J Mol Cell Cardiol. 2009 Oct;47(4):512-9. doi: 10.1016/j.yjmcc.2009.07.010. Epub 2009 Jul 16.
Clinical evidence indicates that intensive insulin therapy during critical illness protects the endothelium and contributes to prevention of organ failure and death but the mechanisms involved remain unclear. This study was designed to test the hypothesis that insulin inhibits adherence of polymorphonuclear leukocytes (PMNs) to endothelial cells in myocardial ischemia/reperfusion (MI/R) and to investigate the underlying mechanisms. Anesthetized rabbits were subjected to MI/R (45 min/4 h) and randomly received saline, glucose-insulin-potassium (GIK) or GK respectively (2 mL/kg/h, i.v.). In vitro study was performed on cultured endothelial cells subjected to simulated ischemia/reperfusion. In vivo treatment with GIK but not GK attenuated myocardial injury as evidenced by reduced plasma creatine kinase activity, myocardial apoptosis and infarct size in MI/R rabbits compared with the saline group. Interestingly, GIK but not GK significantly decreased coronary endothelial expression of P-selectin and intercellular adhesion molecule-1 (ICAM-1), inhibited adherence of PMNs to coronary endothelium (107.7+/-7.4 vs. 155.0+/-9.2 PMNs/mm(2) in saline group, n=8, P<0.01), and therefore decreased myocardial PMNs accumulation. In cultured endothelial cells subjected to simulated ischemia/reperfusion, insulin (10(-)(7) M) increased Akt activity and eNOS phosphorylation with subsequent NO production, and concurrently exerted an anti-adhesive effect as manifested by reduced endothelial P-selectin and ICAM-1 surface expression and PMNs adherence (13.7+/-1.3% vs. 22.2+/-1.9% in vehicle, n=9, P<0.01), all of which are abolished by the specific Akt inhibitor. Furthermore, inhibition of insulin-stimulated NO production using either the selective eNOS inhibitor cavtratin or the NOS inhibitor L-NAME blocked the anti-adhesive effect of insulin. These results demonstrate that insulin reduces endothelial P-selectin and ICAM-1 expression, and thus inhibits leukocyte-endothelium adherence in MI/R rabbit hearts. The anti-adhesive property by insulin may be mediated by the Akt-mediated and NO-dependent pathway.
临床证据表明，危重病期间强化胰岛素治疗可保护内皮细胞，并有助于预防器官衰竭和死亡，但其涉及的机制仍不清楚。本研究旨在验证胰岛素抑制心肌缺血/再灌注（MI/R）时多形核白细胞（PMN）与内皮细胞黏附的假说，并探究其潜在机制。将麻醉的兔子进行MI/R（45分钟/4小时），并分别随机接受生理盐水、葡萄糖-胰岛素-钾（GIK）或GK（2毫升/千克/小时，静脉注射）。对培养的内皮细胞进行模拟缺血/再灌注的体外研究。与生理盐水组相比，MI/R兔子体内用GIK而非GK治疗可减轻心肌损伤，表现为血浆肌酸激酶活性降低、心肌细胞凋亡和梗死面积减小。有趣的是，GIK而非GK显著降低冠状动脉内皮细胞P-选择素和细胞间黏附分子-1（ICAM-1）的表达，抑制PMN与冠状动脉内皮的黏附（生理盐水组为155.0±9.2个PMN/平方毫米，GIK组为107.7±7.4个PMN/平方毫米，n = 8，P < 0.01），因此减少心肌PMN积聚。在进行模拟缺血/再灌注的培养内皮细胞中，胰岛素（10⁻⁷ M）增加Akt活性和eNOS磷酸化并随后产生NO，同时发挥抗黏附作用，表现为内皮P-选择素和ICAM-1表面表达降低以及PMN黏附减少（载体组为22.2±1.9%，胰岛素组为13.7±1.3%，n = 9，P < 0.01），所有这些均被特异性Akt抑制剂消除。此外，使用选择性eNOS抑制剂cavtratin或NOS抑制剂L-NAME抑制胰岛素刺激的NO产生可阻断胰岛素的抗黏附作用。这些结果表明，胰岛素可降低内皮P-选择素和ICAM-1表达，从而抑制MI/R兔心脏中的白细胞-内皮黏附。胰岛素的抗黏附特性可能由Akt介导且依赖NO的途径介导。
