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Expression and distribution of connexin 43 in myocardium of rats after repeated positive acceleration exposures

Zhou Ying, Sun Xiqing, Wang Bing, Geng Jie, Wang Yongchun

Key Laboratory of Aerospace Medicine,Ministry of Education,Faculty of Aerospace Medicine,the Fourth Military Medical University.Xi'an 710032,Shaanxi

Abstract

The present study was designed to observe the expression and distribution of connexin43 (Cx43) in myocardium of rats after repeated positive acceleration (+Gz) exposures. Thirty six male Sprague-Dawley rats were randomly divided into 3 groups (n=12): control group, +6Gz group and +10Gz group. The rats in +6Gz group were exposed to +6Gz for 3 min daily, 1 week, while rats of +10Gz group were subjected to +10Gz for 3 min daily, 1 week. All animals were anaesthetized and necropsied immediately, 1 d, 3 d and 7 d after the last exposure. The expression and distribution of Cx43 in the ventricles of hearts were examined by immunohistochemistry and Western blot analysis. The immunohistochemistry results showed that in control group abundant expression of Cx43 was observed with intense punctate labelling confined to the intercalated disks between cardiomyocytes. After +Gz exposure, there was a loss of the immunoreactivity of Cx43, which was consistent with Western blot results, and distribution changes of Cx43, with an increase in side-side Cx43 and a decrease in end-end Cx43. Western blot analysis revealed that Cx43 expression was modified in response to different exposure program and different recovery time. The protein expressions of Cx43 were lower at 4 time points after exposure in either +6Gz or +10Gz groups compared with that in the control group (P<0.001). Densitometry analysis of immunoblots revealed a decrease in the total amount of Cx43 signals immediate after exposure while an increase during the recovery time. After 7-day recovery, the amounts of Cx43 of two exposure groups were still lower than that in the control group (P<0.001). The decrease of Cx43 expression in +10Gz group was more significant that in +6Gz group. The results demonstrated that the decrease and distribution disturbance of Cx43 in the ventricle of rats after repeated +Gz exposures could be recovered. These findings facilitate our understanding of the mechanisms of arrhythmias caused by +Gz and provide new protective measures.

Key words: acceleration;Myocardium;connexin 43;Immunohistochemistry;Western blot

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Citing This Article：

Zhou Ying, Sun Xiqing, Wang Bing, Geng Jie, Wang Yongchun. Expression and distribution of connexin 43 in myocardium of rats after repeated positive acceleration exposures. Acta Physiol Sin 2008; 60 (3): 320-326 (in Chinese with English abstract).