Abstract: ObjectiveTo investigate the role of Ca²⁺ cell signaling molecules in cardiac injury caused by 10% hypoxia combined with water and dietary depletion in rats.MethodsEighty Wistar rats were randomly divided into a control group,hypoxia group,food and water depletion group,and hypoxia combined with water and food depletion group.The rats with hypoxia were placed in a normbaric chamber with the air containing 10% oxygen.Biochemical methods were adopted to observe the changes of serum metabolic enzymes and transmission electron microscope was used to detect the change of cardiac ultrastructure and immunohistochemistry to detect the expessions of calmodlin(CaM)and cyclic adenosine monophosphate(cAMP) response element binding protein(CREB)at 1st,3rd,5th and 7th day of the experiment in the rats.ResultsAt 7th day of the experiment,the serum lactic dehydrogenase(LDH)(1628.40±460.8 U/L)and aspartate aminotransferase(AST)(394.60±187.18 U/L)increased in the rats of hypoxia combined with water and food depletion compared to those of the control group(578.40±135.04 and 136.40±14.59 U/L);the myocardial cells presented irregular shape nucleus,marginated chromatin,increased perinuclear space,swelled mitochondria,increased empty or compensatory mitochondria,Z lines derangement even dissolvement,sarcoplasmic reticulum mild dilation and sarcolemma swelling with finger-like processes;in addition,degeration or apoptosis of interstitial cells and vascular endothelial cells were also observed.The expressions of CaM(4.22±0.84)in the cytoplasm of myocardial cells were increased and those of phophorylated CREB(3.57±0.55)in the nucleus were incresed at 7th day in the rats of hypoxia combined with water and food depletion group compared to those of the control group(CAM:0.73±0.41,CREB:0.90±0.41).ConclusionHypoxia(10% oxygen)combined with water and food depletion might result in damages of struture and function of cadiac cells and the activation of Ca²⁺ cell signaling transduction(increased expression of CaM and phosphorylated CREB may play an important role in the damages.