Changes and significance of levels of Gs¦Á and Gi¦Á and their mRNA in myocardium undergoing ischemic reperfusion

    ZHONG Qianª²Jin, WANG Zengª²Wei, XIAO Yingª²Bin

    1Department of Cardiovascular Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China, 2Department of Cardiovascular Surgery, General Hospital of Shenyang Military Region, Shenyang 110016, China

    ¡¾Abstract¡¿ AIM: To study the changes of the levels of ¦Á subunits of stimulatory (Gs¦Á) and inhibitory (Gi¦Á) guanine nucleotideª²binding protein and their mRNA in newborn guineaª²pig myocardium undergoing global ischemic reperfusion and to explore the relation between these changes and cardiac functions. METHODS: Thirty newborn guineaª²pigs 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¢ñ, arrested by St. Thomas Hospital cardioplegic solution ¢òsimultaneously in group ¢ò and arrested by cold blood cardioplegia simultaneously in group ¢ó. All the hearts were reperfused for 60 min. Cardiac functions and the levels of Gs¦Á and Gi¦Á and their mRNA were investigated. RESULTS: The cardiac functions were markedly deteriorated in group ¢ñand group ¢ò during reperfusion (P<0.01), whereas no pronounced changes of cardiac functions were found at the end of reperfusion in group ¢ó (P>0.05). Significant decreases of the levels of Gs¦Á and its mRNA (P<0.01) and notable increases of levels of Gi¦Á and its mRNA (P<0.01) were found in group ¢ñand group ¢ò after ischemia and after reperfusion when compared with those before ischemia and in group ¢ó, but recovery to the levels of Gs¦Á and Gi¦Á and their mRNA before ischemia was achieved in group ¢ó after reperfusion (P>0.05 vs before ischemia). CONCLUSION: Ischemic reperfusion injury of immature guinea pig myocardium may result from the unbalance between Gs¦Á and Gi¦Á. ......