| AimThe liver suffers a pathophysiologic process of c during hepatic section and liver graft. Liver hasnt much tolerance to ischemia, and after hepatic ischemia reperfusion, many adverse events, such as lipid peroxide reactions and a massive generation of reactive oxygen species (ROS) , induce hepatocellular injury and metabolizable unbalance. Heat shock protein 70 (HSP70) is a kind of endogenous and protective protein and expresses to enhance cellular tolerance when the body suffers stress stimulations. It has confirmed that HSP70 protects the liver from ishemia reperfusion injury, but the protective mechanism is unclear so far. In this study, the rats were randomly divided into heat stress pre-treatment group and non - heat stress pretreatment group, in which the expression of HSP70, the content of SOD and MDA in liver, the levels of serum enzymes of aspartate aminotransferase ( AST) , alanine aminotransferase ( ALT) and the pathological changes of the liver were detected at 0,4,8,12 and 24h after ischemia reperfusion (I/R). We discuss the protective mechanism of HSP70 induced by the heat stress pretreatment on the hepatic ischemia reperfusion injury-Methods1. Animal grouping and model preparation(1) Animal groupingThe rats were randomly divided into heat stress pretreatment group ( HP +IR) and non - heat stress pretreatment group (IR).(2) Model preparationHepatic ischemia reperfusion model: To establish the models the ischemia reperfusion injury using Pringles maneuver . All rats were anesthetizes with 10% urethane(5ml/Kg ,i. p. ). The abdomen was opened in a median laparatomy, and the hepatoduodenal ligament was detached and champed for 30min using an atraumatic microvascular clip. Reperfusion was accomplished by removing the clip.Heat stress pretreatment: After being anesthetized, the rat liver was expo-sured, then the head of thermal sensor was placed under the left lobar of the liver to observe the changes of hepatic temperature. Local heating with hair drier raised the body temperature to 42 +0.5C ,and maintained this temperature for 15 min, and then the abdomen was closed after heating.2. Measured items(1) The expression of HSP70 in hepatic tissue: Using strept avidin - biotin - enzyme complox ( SABC ) assay. The negative control was performed with PBS that insteaded of anti - HSP70 antibody.( 2 ) The activing of SOD and the content of MDA: The activity of SOD in hepatic tissue was measured by xanthine oxygenation enzyme assay, and the content of MDA was detected by TBA. The serum levels of AST and ALT were measured by auto - biochemical analyzer.(3) Hepatic histology studyLiver samples were fixed in 10% neutral buffered formalin, paraffine -embedded , and cut into sections, and stained with hematoxylin - eosin according to the standard procedures. The histopathologically hepatic alterations were observed with the microscope.Other liver samples were fixed in 2. 5% glutaraldehyde to study the histopathologically hepatic changes with the transmission electron microscope.3. Image processingUsing the image quantitative analysis system technique, after offering images with digital camera, then imputing the images into the computer, measuring average gray and integrated optic density value of positive HSP70 in the samecondition.4. Statistical analysisThe date were expressed as mean SEM. The Student test was performed to evaluate the significant difference between groups.Results1. In hepatic tissue, the positive product of HSP70 presented in many brown - yellow pellets with immunohistochemical assay. These pellets existed in the nucleolus during the heat shock phase, while they appeared in the cytoplasm after heat shock reaction. The results of image quantitative analysis indicated that the expression of HSP70, because of heat stress, increased and peaked at 12h,and then decreased as time went.2. The expression of HSP70 in hepatic tissue gradually decreasedwhile the duration of ischemia and reperfusion extended in both gr...
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