Abstract: Objective To study the changes in proteomic profile of myocardium in rats with spontaneous hypertension（SH）.Methods Whole tissue protein was extracted from free wall of left ventriclar myocardium of rats with SH and normal control Wistar Kyoto（WKY） rats,and separated by 2-dimensional electrophoresis（2-DE）.After stained with Coomassie brilliant blue,7 differentially expressed protein spots were identified by flight mass spectrometry（MALDI-TOF） and then subjected to mass fingerprint analysis.Results 2-DE could separate 454±45 proteins with an average spot matching rate of 91.1%.Twenty-seven proteins were differentially expressed in myocardial tissue from rats with SH.The 6 proteins identified by MALDI-TOF were energy metabolism associated pyruvate dehydrogenase E1α and creatine kinase,cell stress associated glucose-regulated protein 50,alpha B-crystallin,cell growth associated tripartite motif protein 50 and 4,and a half LIM domain.Of these 6 proteins,the creatine kinase level was lower while the levels of the other 5 proteins were higher in rats with SH than in normal control rats.Conclusion Energy metabolism,stress and cell growth-related protein expression are significantly changed in rats with SH before the presence of increased blood pressure and myocardial hypertrophy.