2.1 MPa和4.1 MPa氢氧环境下鼠生存的生物学评价

目的对处于高压氢氧环境下的小鼠和大鼠进行生物学毒性鉴定及生物效应评价。方法将实验鼠在2．1MPa和4．1MPa氢氧环境下暴露1～10h，以常压和对应高压氦氧环境作为对照。脑组织过氧化损伤、电生理和脑组织兴奋性毒性指标在高压下动态测定，各器官组织学、细胞应激和过氧化损伤指标在高压暴露前后测定。结果进行高压实验的动物全部存活。小鼠在10h的氢氧暴露期间以及返回常压后，脑电（EEG）密度谱并未改变。4个月后电镜下脑、肝未见异常。2．1MPa氢氧环境下小鼠脑干听觉诱发电位（BAEP）潜伏时比常压下略有延长；在4．1MPa氦氧和氢氧环境下BAEP潜伏时进一步延长，以氢氧环境更为明显。2．1MPa氦氧和氢氧环境下，大鼠血浆热应激蛋白（HSP-70）含量和小鼠脑细胞外液丙二醛（MDA）含量均略有升高。在大鼠心、肾、肝、脑中，只有肾脏MDA含量在氢氧暴露后出现异常升高。在2．1MPa氢氧与氦氧环境下，小鼠脑细胞外液谷氨酸含量未见差异，大鼠脑组织NO含量未呈现差异。结论在4．1MPa高压氢氧环境中，静水压与H2均有阻碍突触传递的作用，并且二者作用是叠加的。在2．1MPa高压氢氧环境中，除了肾脏的过氧化负担增加外，脑细胞兴奋性毒性、皮层电活动、细胞应激和细胞形态学指标均说明1～10h以内的暴露是安全的。

Biological evaluation of mice and rats exposed to 2.1 MPa and 4.1 MPa H2-O2

Objective To make bio-toxicological evaluation and investigate the effects of hyperbaric H2-O2 exposure on mice and rats, using H2-O2 as diving breathing gas. Methods Experiments were performed with mice and rats exposed to 2. 1 MPa or 4. 1 MPa H2-O2 for 1 - 10 h, while identical He-O2 and normal pressure were used in the control group. Dynamic indices of intracerebral peroxidation lesion, excitotoxicity, and electro-physiology were measured during exposure. Indices of histology, cell stress and peroxidation of various organs were measured before and after exposures. Results After a 10 h H2-O2 exposure at 2. 1 MPa, EEG power density was identical to that of the He-O2 exposure. Electron microscopy revealed there were no significant abnormal changes in the brain and liver. Latencies of brainstem auditory evoked potential measured at 2. 1 MPa were lengthened, which was more prominent at 4. 1 MPa. At 2. 1 MPa, the content of heat stress protein in the plasma and malonaldehyde in the brain extracellular fluid were elevated slightly. The content of MDA only in the kidney rather than in the brain, liver and heart was shown to be higher. No differences in the concentrations of extracellular glutamate or cerebral nitric oxide could be detected. Conclusions Synaptic transmission was synergistically suppressed in 4. 1 MPa H2-O2 environment by both pressure and hydrogen. Acute exposure to 2. 1 MPa H2-O2 for a duration of less than 10 h was harmless in terms of excitotoxicity, cell stress response, cerebral electric activity and cell histomorphology, except for a little increase in the load of peroxidation in the kidney.