Abstract: To investigate the effect of doxorubicin (DOX) on gene expression of the myocardial sarcoplasmic reticulum (SR) Ca²⁺ transport proteins and the mechanism of taurine (Tau) protecting cardiac muscle cells, 9 rabbits were injected with DOX, 8 rabbits with DOX and Tau, and 9 rabbits with normal saline. Cardiac function, concentration of calcium in cardiomyocytes (Myo[Ca²⁺]_i), activity of SR Ca²⁺-ATPase(SERCA2a), level of SERCA2a mRNA and Ca²⁺ released channels(RYR2)mRNA were detected. The left ventricle tissues were observed by electron microscopy. The results showed that cardiac index, left ventricular systolic pressure, activity of SR Ca²⁺-ATPase and level of SERCA2a mRNA decreased, while Myo[Ca²⁺]_i increased in DOX-treated rabbits. DOX could not affect the level of RYR2 mRNA. Tau intervention could alleviate the increase of left ventricular diastolic pressure, Myo[Ca²⁺]_i and the decrease of SERCA2a mRNA induced by doxorubicin. The results suggested that downregulation of SERCA2a gene expression was an important mechanism of DOX-induced cardiomyopathy and that Tau could partially improve the heart function by reducing calcium overload and alleviating downregulation of SERCA2a mRNA.

Key words: Doxorubicin, Ca²⁺-ATPase, Ryanodine receptor, Taurine, Gene expression

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