Changes Of Connexin40 And Connexin45 Expression In Sinoatrial Node And Atriventricular Junction Arean Of Rats After Exhausted Exercises

Objective:To observe the rule of change on the morphology and the expression of Connexin40(Cx40) and Connexin45(Cx45) in Sinoatrial node(SAN) and Atrioventricular junction area(AJA) after repeated and single bout of exhausted training.Methods:Ninety male Sprague-Dawley rats were divided into control group,single bout of exhausted swimming groups and 2-week repeated exhausted swimming groups.Then each of two swimming groups were divided into immediate,6h,12h and 24h groups and should be killed at those moments after the last exercise.Then we applied respectively HE staining,Masson staining and immunohistochemistry straining to study the changes of morphology and the content of Cx40,Cx45 in SAN and AJA of rats.Results:(1) In training groups,it showed the ischemic and hypoxic morphologic change and abnormally proliferated of collagen fiber in SAN and AJA of rats.(2) After training the distribution of Cx40 and Cx45 lost their rule and they transferred to cytoplasm from cytomembrane and gathered.The expression of Cx40 and Cx45 deficited in training groups.(3) Intergrated optical density(IOD)of Cx45 declined after training.The declining of Cx45 IOD showed remarkable(p＜0.05) in 6h groups after two kinds of exhausted training in SAN.And it just significant decreasd in 6h group after 2-week repeated exhausted swimming(p＜0.05) in AJA.(4) Cx40 IOD reduced after training in SAN and AJA.In SAN it just had remarkable decreased in 6h group(p＜0.01),then rised in 24h group after single bout of exhausted swimming.After 2-week repeated exhausted swimming Cx40 IOD declined significantly in 6h(p＜0.01) and 12h(p＜0.05) groups and 6h group remarkable decreased than 12h and immediate groups (p＜0.05).Cx40 IOP in 6h group of 2-week repeated exhausted swimming remarkable declined than single bout of exhausted swimming(p＜0.05).In AJA Cx40 IOD had remarkable decreased in 6h and 12h groups(p＜0.01),then rised significantly in 24h group(p＜0.05) after single bout of exhausted swimming.After 2-week repeated exhausted swimming Cx40 IOP declined significantly in 6h(p＜0.01),12h(p＜0.05) and 24h groups(p＜0.05) and 6h group remarkable decreased than immediate and 24h groups(p＜0.05). Conclusion:Two kinds of exhausted training could result in declining of expression and distribution change of Cx40 and Cx45 and morphology of ischemic and hypoxic change in SAN and AJA,which contacts with exercise-induced myocardial microinjury.