Giα2和Giα3蛋白在心脏缺血预处理中的作用

EFFECTS OF CARDIAC Giα2 and Giα3 PROTEINS DURING ISCHEMIC PRECONDITIONING

目的：研究离体大鼠心脏缺血预处理对Ｇ蛋白的影响。方法：免疫印迹法测定心肌细胞膜Ｇｉα２、Ｇｉα３和Ｇｓα含量；放射免疫法测定腺苷酸环化酶活性。结果：与对照组相比，缺血再灌注组心功能受到明显损伤，缺血预处理组心功能显著恢复。各组心脏Ｇｓα含量无明显变化；缺血再灌注组Ｇｉα含量明显升高，腺苷酸环化酶活性降低；缺血预处理组与缺血再灌注组相比Ｇｉα２和Ｇｉα３含量分别下降４１．３％和３４．５％，腺苷酸环化酶活性升高。结论：缺血再灌注可引起腺苷酸环化酶信号转导系统功能障碍，缺血预处理可明显减轻缺血再灌注损伤，使细胞膜信号转导功能恢复。

ABSTRACT Objective: To study the alteration of G proteins in ischemic preconditioning. Methods: Levels of Gsα, Giα2 and Giα3 in sarcolemma were measured by Western blot analysis. Adenylyl cyclase activities were determined by radio immunoassay. Results: Cardiac function parameter decreased significantly during ischemiareperfusion, and increased significantly during ischemic preconditioning. Expressions of Gsα were unchanged. During ischemiareperfusion, contents of Giα2 and Giα3 increased, and adenylyl cyclase activities decreased. During ischemic preconditioning, contents of Giα2 and Giα3 decreased 41.3% and 34.5% respectively compared with ischemiareperfusion. Adenylyl cyclase activities increased. Conclusion: Ischemiareperfusion may contribute to the dysfunction of adenylyl cyclase signal transduction system. Ischemic preconditioning can attenuate ischemiareperfusion injury and improve the function of adenylyl cyclase signal transduction system.