心肌缺血再灌注时Gsα和Giα蛋白含量mRNA水平变化及意义

Changes and significance of levels of Gsα and Giα and their mRNA in myocardium undergoing ischemic reperfusion

目的:研究新生豚鼠心肌缺血再灌注时Gsα和Giα蛋白含量及其mRNA水平的变化以及与心功能变化的关系.方法:30只新生豚鼠随机分为3组(每组n=10),建立离体心脏左心做功模型.组Ⅰ:离体心脏缺血90min;组Ⅱ:缺血时予ThomasⅡ号液;组Ⅲ:缺血时予冷血心停搏液.各组均再灌注60min.检测心功能指标,Gsα和Giα蛋白含量及其mRNA水平的变化.结果:组Ⅰ和组Ⅱ在再灌注时的心功能明显受损(P<0.01),组Ⅲ在再灌注结束时无明显变化(P>0.05).组Ⅰ和组Ⅱ在缺血后和再灌注后Gsα蛋白含量分别为缺血前的37.5%,40.3%,36.6%和39.5%,GsαmRNA水平分别为缺血前的38.6%,41.4%,35.7%和40.1%,明显降低(P<0.01);Giα蛋白含量分别为缺血前的198.1%,175.4%,201.3%,181.4%,Gi2αmRNA水平分别为缺血前的215.4%,180.2%,210.3%和176.2%,显著升高(P<0.01).组Ⅲ在再灌注后Gsα和Giα蛋白含量及其mRNA恢复至缺血前的水平(P>0.05).结论:Gsα和Giα蛋白的平衡遭受破坏可能是未成熟心肌缺血再灌注损伤发生的机制之一.

AIM： To study the changes of the levels of α subunits of stimulatory （Gsα） and inhibitory （Giα） guanine nucleotide-binding protein and their mRNA in newborn guinea-pig myocardium undergoing global ischemic reperfusion and to explore the relation between these changes and cardiac functions. METHODS： Thirty newborn guinea-pigs were randomly assigned to three groups （ n = 10 in each group） and isolated perfused working heart models were established. The newborn hearts suffered global ischemia alone for 90 min in group Ⅰ , arrested by St. Thomas Hospital cardioplegic solution Ⅱ simultaneously in group Ⅱ and arrested by cold blood cardioplegia simultaneously in group III. All the hearts were reperfused for 60 min. Cardiac functions and the levels of Gsα and Giα and their mRNA were investigated. RESULTS： The cardiac functions were markedly deteriorated in group Ⅰ and group Ⅱ during reperfusion （P〈0.01）, whereas no pronounced changes of cardiac functions were found at the end of reperfusion in group Ul （ P 〉 0.0.5 ）. Significant decreases of the levels of Gsα and its mRNA （ P 〈 0.01 ） and notable increases of levels of Giα and its mRNA （P〈0.01） were found in group Ⅰ and group Ⅱ after ischemia and after reperfusion when compared with those before ischemia and in group Ⅲ, but recovery to the levels of Gsα and Giα and their mRNA before ischemia was achieved in group Ⅲ after reperfusion （ P 〉0.05 vs before ischemia ）. CONCLUSION： Ischemic repeffusion injury of immature guinea pig myocardium may result from the unbalance between Gsα and Giα.