Abstract:

Abstract:Objective
To establish rat model of smoking-dosage cadmium and  study the effect of smoking-dosage cadmium on myocardial injury in rats,and to explore its molecular mechanism.Methods The rat models of smoking-dosage cadium were established as model group,control group was set up at the same time.The rats in 20,36 and 52 weeks were killed,then the contents of cadmium in heart and the changes of heart organ coefficient in rats were investigated.The contents of creatine kinase(CK),lactate dehydrogenase(LDH),glutathion(GSH),malonaldehyde(MDA) and activity of superoxide anion dismutase(SOD) in myocardial tissues were detected.The histopathological changes of myocardium were observed by light microscope with HE staining.RT-PCR was performed to examine the caspase-3,bcl-2 and bax mRNA expressions.Western blotting was used to determine the caspase-3,bax,caspase-9 and Fas protein expressions.Results Compared with control group,the contents of cadmium in model group were increased in 36 and 52 weeks（P<0.05）,the organ coefficient of heart in model group was significantly decreased in 52 weeks（P<0.05）,and the contents of CK and LDH in model group were increased obviously in 20,36 and 52 weeks（P<0.05）,and the activities of SOD in model group were decreased in 36 and 52 weeks（P<0.05）,the contents of GSH in model group were decreased in 20,36 and 52 weeks（P<0.05）,the contents of MDA in model group were increased in 20,36 and 52 weeks（P<0.05）.The myocardial cell disorder and focal hyperplasia of connective tissue were observed in model group by light microscope with HE staining.The results of  RT-PCR and Western blotting showed that  the expressions of caspase-3,bax and Fas were increased（P<0.05） and the expression of bcl-2 was decreased （P<0.05）.Conclusion Smoking-dosage cadmium can do harm to rat heart through  decreasing the cardiac enzymes and oxidative stress,at last result in the apoptosis of myocardial cells.

Key words: smoking-dosage cadmium;rats,Wistar;heart;apoptosis