Abstract: Objective To investigate the change of apoptosis factors Bax,Bcl-2,cytochrome C,and caspase-3 and their role in the mechanism of myocardial cells injury under hypoxia combined with water and dietary depletion in rats.Methods Eighty wistar rats were placed in a self-designed normobaric hypoxic chamber with the oxygen concentration of 10%.In situ cell apoptosis detection,immunochemistry and in situ hybridization were used to detect the change of apoptosis index of myocardial cells and the expressions of Bax,Bcl-2,cytochrome C,and caspase-3 in the process at 1st,3rd,5th,and 7th day after the treatment.Results The apoptosis index of myocardial cells was increased at 1st and 7th day under the condition (62.63±14.97,20.19±3.26).The expressions of Bax,cytochrome C,and caspase-3 were increased from 1st to 7th day in hypoxia group and hypoxia combined with water and dietary depletion group,and from 3rd to 7th day for water and dietary depletion group.The expression of Bcl-2 was reduced from 1st to 7th day in hypoxia group and water and dietary depletion group and from 3rd to 7th day in hypoxia combined with water and dietary depletion group.The mRNA of caspase-3 was increased at 1st day(4.19±1.42,3.87±0.86)and 7th day(10.43±2.79,12.12±2.27)in hypoxia group and hypoxia combined with water and dietary depletion group,and at 1st day in water and dietary depletion group(3.85±0.88).Conclusion The hypoxia of 10% oxygen concentration combined with water and dietary depletion could result in apoptosis of myocardial cells which was correlated with the increase of promoting apoptotic factor(Bax)and the decrease of anti-apoptotic factor(Bcl-2).Furthermore,it might result in release of cytochrome C by mitochondria pathw ay,activation of caspase-3,and apoptosis of myocardial cells.