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[Calpain mediates cardiac troponin I degradation in tail-suspended rats.] [Ariticle in Chinese]

XU Peng-Tao, SONG Zhen, LI Quan, ZHANG Lin, WANG Yun-Ying, YU Zhi-Bin^*

Department of Aerospace Physiology, the Fourth Military Medical University, Xi'an 710032, China

Abstract

The aim of the present study was to investigate the expressions of calpain and calpastatin in the myocardium of simulated
weightlessness rats, and to elucidate the underlying mechanism of cardiac troponin I (cTnI) degradations. Tail-suspended (SUS) rats were
used as a simulated weightlessness model on the ground. The myocardium of rats was homogenized, and the expressions of calpain-1,
calpain-2, calpastatin and cTnI were analyzed by Western blotting technique. Calpastatin expression was significantly decreased in 2-
and 4-week SUS groups compared with that in the synchronous controls (P<0.05). Calpain-2 expression was slightly decreased, whereas
calpain-1 expression was unaltered in SUS groups. However, calpain-1/calpastatin and calpain-2/calpastatin ratios were increased after tailsuspension,
being significantly higher in 2- and 4-week SUS groups than those in the synchronous controls (P<0.05, P<0.01). Cardiac TnI
degradation was significantly increased after tail-suspension (P<0.01), but cTnI degradation in both SUS and control groups was
significantly inhibited by a non-specific inhibitor of calpain, PD150606 (P<0.01). These results suggest that an increase in calpain activity
may enhance cTnI degradation in the myocardium of tail-suspended rats.

Key words: calpain; calpastatin; cardiac troponin I; simulated weightlessness; protein degradation

Received: 2010-07-06　　Accepted: 2010-08-04

Corresponding author: 余志斌　　E-mail: yuzhib@fmmu.edu.cn

Citing This Article：

XU Peng-Tao, SONG Zhen, LI Quan, ZHANG Lin, WANG Yun-Ying, YU Zhi-Bin. [Calpain mediates cardiac troponin I degradation in tail-suspended rats.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (5): 415-420 (in Chinese with English abstract).