| Background:Heart is the important target organ of ischemia and hypoxia during the early stage of burns. Cardiac inadequacy could directly cause or deteriorate the damage of ischemia and hypoxia within all body organs, and also the main cause of functional disturbance in other body organs. Previous researches showed that in the early stage of serious burns, organic lesion of cardiac muscle had been existed. Thus it is profoundly meaningful to investigate how cardiocyte damage is caused by ischemia and hypoxia after serious burns, and how to block its damage mechanism in order to protect cell function. By doing all these mentioned above, the multiple organ failure after serious burns could be decreased, and survival rate of patients could be raised. Recently, how to protect cell function by endogenous anti-damage method has received more and more attention of scholars both domestically and abroad.Heat shock protein90 (HSP90) is the essential molecular chaperones during the process of maintaining the stability of intra-cellular protein conformation as well as the normality of its function. HSP90 is also the received protective molecule which closely related to stress tolerance. Through catalyzing the redoubling of damaged and degenerative protein, HSP90 promotes the disaggregation of protein and refrains molecule from damage caused by stress. Besides that, HSP90 interacts with various key molecules in the path ways of stress signal transduction. Both serine threonine kinase (AKT), which plays an important role in anti-apoptosis, and upriver phosphoinositide–dependent kinase-1 (PDK1) are HSP90's substrate proteins.objective:To investigate the effect of HSP90 on the expression of AKT in hypoxic cardiocytes, to observe the effect of HSP90 and AKT on the molecular vital impulse and apoptosis, and further more to investigate the molecular mechanism that HSP90 endogenously protect cardiocyte from damage after hypoxia . Methods:By setting up the model of hypoxic cadiocyte of neonatal rat, the effect of HSP90 was restrained by Geldanamycin (GA), the specific blocking agent of HSP90. The level of AKT in cardiocyte was determined by Wester-blot and the cardiocyte vital impulse at different time of hypoxia was dectected by MTT. The change of cardiocyte ultrastructure was obsevered by TEM. Cardiocyte apoptosis was detected by TUNEL.Results:(1) The expression of AKT in hypoxic cardiocyte begined to increase from 3h after hypoxia, reached to the peak at 6h, and deceased at 24h. After GA was added, the total expression of AKT begined to decrease at 6h after hypoxia, and reached to the bottom at 24h.(2) MTT showed that cardiocyte vital impulse first begined to decrease at 12h after hypoxia, and decreased significantly at 24h-48h in GA+hypoxia group; compared with hypoxia group, cardiocyte vital impulse in GA+ hypoxia group dropped significantly ( p < 0. 05 ).(3) Transmission electron microscope showed the evident damage of hypoxic cardiocyte ultrastructure after blocking HSP90: caryotheca crenation, chromatin margination and mitochondria vacuole. (4)Apoptotic index (AI) in normal control group was (1.9±0.3) %; AI in hypoxia group was (10.7±1.2) %, which obviously higher than in normal control group (p < 0. 05); AI in GA+ hypoxia group was (26.3±5.3) %, which also obviously higher than in normal control group(p < 0. 01).Conclusions:As a molecular chaperones of AKT, HSP90 took part in the adjustment of PI3K/AKT signal path way to stress and played an important role in maintaining molecular vital impulse and preventing apoptosis.
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