Objective:To investigate the mechanism of effects of endoplasmic reticulum stress on apoptosis of cardiomyocyte in hyperlipidemia rats. Methods:Rat model of established with fatty dieting.After twelve weaks

the serum triglycerides(TG)and cholesterol (TC)were oberserved by completely automatic biochemistry meter;The pathological changes of myocardial tissue were detected by HE staining;The apoptosis of cardiomyocyte were tested by TUNEL. The expression of endoplasmic reticulum stress associated molecular glucose regulated protein 78 in myocardial tissue were tested byimmunohistochemistry and RT-PCR. Results :The levels of TC and TG in blood sera of control group did not change after 12 weeks

while TC and TG in model group significantly increased along with the te mporal prolongation compared with those in control group ( P <0.01 ) . The expression of GRP78 mRNA and protein in myocardiocyte of rats in model group significantly increased with those in control group ( P<0.05 ) . Enhanced expression of GRP78 could be induced by fatty diet. Couclusion:The hyperlipidemia maybe can induce myocardiocyte apoptosis through endoplasmic reticulum pathways.