蛋白激酶B参与门静脉高压症高动力循环的研究

Effect of AKT on splanchnic hyperdynamic circulation in portal hypertension

目的探讨蛋白激酶B(AKT)与肝硬化门静脉高压症(portal hypertension,PHT)高动力循环的关系,特别是AKT与肝门静脉高压症内脏血管收缩反应性降低的关系。方法将SD大鼠随机分为4组:正常对照组(N组,n=7)、四氯化碳诱导的肝硬化门静脉高压组(PHT组,n=7),经AKT特异性阻滞剂LY294002处理的门静脉高压组(LY组,n=7)和注射二甲基亚枫(DMOS)的门静脉高压组(DMOS组,n=7),分别测量门静脉压力(portal vein pressure,pp),离体肠系膜分支动脉对缩血管物质去甲肾上腺素(norepinephrine,NE)的反应性,应用LY294002对离体微动脉收缩反应性的影响以及肠系膜动脉内皮细胞内AKT、内皮一氧化氮合酶(eNOS)的蛋白表达变化。结果①与N组相比,PHT组PP明显增高(P<0.01),应用LY294002后,PP无明显降低(P>0.05);②PHT组肠系膜微动脉对NE的反应性较N组明显降低(P<0.01),LY294002可改善这种低反应性(P<0.01);③AKT在PHT肠系膜动脉内皮中的表达明显上调(P<0.05),eNOS的表达PHT组和N组无明显差别(P>0.05),但p-eNOS的表达在PHT组动脉内皮中明显增高(P<0.05)。结论肝硬化门静脉高压症的内脏动脉中,AKT的表达上调,通过促进eNOS的活化和降低血管收缩反应性,参与内脏高动力循环的形成。

Objective To investigate the role of AKT in hyperdynamic circulation of PHT,and to analyze its effect on the contractility of splanchnic arteries and the possible mechanism.Methods All the rats involved in this experiment were divided into four groups,as normal rats （group N,n=7）,CC14 induced portal hypertension rats （group PHT,n=7）,rats with portal hypertension treated by LY294002 （group LY,n=8） and portal hypertensional rats treated by DMOS （group DMOS,n=7）.The levels of portal vein pressure （PP） were tested respectively.Vascular reactivities of isolated mesenteric microcirculational arteries to norepinephrine （NE） were determined by a vessel perfusion system.The expressions of AKT and eNOS were detected with Western blotting.Results ① The pp of group PHT was apparently higher than that of the group N （P＜0.01）,LY294002 had little effects in reducing pp of PHT rats （P＞0.05）; ② Compared with group N,the contractility of group PHT to NE decreased obviously （P＜0.01）,LY294002 could partially attenuate this vasohyporesponsiveness （P＜0.01）; ③ There was no significant difference in levels of eNOS in both groups （P＞0.05）,but the protein levels of AKT and p-eNOS were highly upregulated in group PHT,compared with group N （P＜0.05）.Conclusion The excessive expression of AKT in mesenteric arteries may participate in development of splanchnic hyperdynamic of PHT,the possible mechanism may be invdving the activation of eNOS and impair of the contractility of mesentery artery to NE.