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With the development of society, the purpose of the development of marine resources, archaeological adventure or military operations, underwater activities more and more common and frequent. Personnel to enter the underwater gas equal to the surrounding water pressure must be breathing. Respiratory gas separated inert gas (inert gas refers to the physiological pressure increased, the most common is the nitrogen), with the dive time and increase in depth, while continuously dissolved in the body tissue, which requires subsequent decompression must follow certain rules, or inert gas may be too quickly overflow, tissue and blood \The DCS can cause various manifestations of skin itching, joint pain, respiratory and circulatory disorders, and nervous system damage, severe cases can cause divers to rapid death. Prevention DCS core areas of underwater operations security. Hyperbaric oxygen (hyperbaric oxygen, HBO) is the primary means of treatment of DCS. In recent years, the study found, HBO preconditioning can effectively prevent a variety of hypoxic ischemic injury. DCS also has the characteristics of the pathophysiology of ischemia and hypoxia, HBO preconditioning of DCS also has a preventive effect? ??Purpose of this project is to observe the HBO preconditioning rats DCS prevention effect and its mechanism. The study is divided into two parts. The first part, establish a rat model of air diving decompression sickness. Appropriate \min. Learn from the overall behavior, gross and microscopic pathology, inflammatory response screening assessment index system. Control the exposure of high-pressure pressure - time - decompression rate and tumble sport, can be prepared with stable incidence of decompression sickness model in rats, and observing rat behavior change; including behavioral, lung and central nervous system pathologic and microscopic pathology as well as inflammatory indicators, including the model evaluation system. The second part of the HBO preconditioning effect and its mechanism for the prevention of DCS in rats. The study was divided into two. The ① HBO preconditioning effect observed. Adult SD rats HBO (250 kPa-60min) (n = 33), 18 h after simulated air diving (700kPa-100min), rapid decompression (200 kPa / min) animals in the cage to 3 m / min rate of 30 min, a DCS incidence was observed. The control animals of each of the atmospheric air (n = 30) or normoxia high nitrogen gas mixture (11 = 13) Pretreatment. The results showed that the incidence of HBO preconditioning group (30.3%) was significantly lower than that of the air control group (63.3%) (p lt; 0.05); normoxic high nitrogen preconditioning on DCS incidence of no significant impact (61.5%). The ② HBO preconditioning mechanism studies, this section is divided into two steps. First, the nitric oxide (nitric oxide, NO) in the HBO preconditioning role in the effects observed. Detected immediately after the HBO exposure and 18h ??rat brain, spinal cord and lung NO content; observe the application of nitric oxide synthase (nitric oxide synthetase, NOS) inhibitor N-nitroso-L-arginine methyl ester (NG-Nitro-L-arginine Methyl Ester, L-NAME) HBO preventive effect. HBO exposure immediately after the rat brain, spinal cord and lung NO content was significantly higher (p lt; 0.05), L-NAME could inhibit this effect; 18h organization NO after exposure showed no significant change. L-NAME significantly confrontation HBO DCS prevention, the incidence rate rose again to 71.4% (p lt; 0.05). Second, heat shock proteins (heat shock protein, HSP) 70 on HBO through and NO prevention DCS observation. Detected 18 h after HBO exposure of rat brain, spinal cord and lung HSP70 expression observed L-NAME and HSP inhibitor quercetin (Quercetin, Q) induced HSP70 expression and Q HBO preventive effect for HBO . HBO after exposure to 18 h, rat brain, spinal cord and lung HSP70 expression was significantly higher L-NAME and Q can inhibit HSP70 increased. Q can be effective against the the HBO DCS prevention, animal DCS incidence significantly rebounded to 69.2% (p lt; 0.05). These results draw the following conclusions: 1.18 h before HBO preconditioning can effectively prevent the occurrence of rats DCS; 2.HBO NO-induced HSP70 expression, and thus play a protective effect of DCS injury.
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