| Infrasound produced by the mechanic vibration of materials, is a kind of sound wave which frequency rate is between 0.0001-20HZ and exists widely in nature. As it has special physical properties, that is, lower frequency rate and longer ware length than the audible sound wave, infrasound travels longer distance in air and has stronger penetrating ability that usual sound-insulated and sound-absorpted materials, especially the helmets of astronauts, couldn't prevent its penetration.Stress is an unspecial physiologic response resulted from changes of neuroendocrine system reaction to the severe and harmful stimulation. But under some conditions, this response could become a kind of disease, namely stress disease. About 75%-90% of epidemic diseases in developed countries have been considered to have relations with the activation of stress system. Thosestimulations affecting human's health are named as the sources of stress. Infrasound is regarded as one of the sources of stress in environment and exists widely. So the stress induced by infrasound is an inevitable problem in human life and can exert unphysiologic effects on human body and is connected with some pathological changes. The basic mechanism of pathophysiologic response to stress induced by infrasound is worth further research because of its social significance. The importance of protection human from infrasound are as follows: protecting the wounded in the wartime in order to win the war at last and the workers from being injured in the peacetime to benefit national economic construction. In this paper, the aims of our studies are to investigate the concerned pathergenicity of stress response induced by infrasound and possible protection methods against stress disease.1 The changes of angiotensin II in the hypothalamus and plasma of rats were investigated by radioimmunoassay(RIA) after exposure to infrasound with different intensity and times. The results showed that: angiotensin II in plasma of the rats exposed to infrasound with 90dB for once, began to increase at 0.5h, and reached it's peak at 12h, which was 186 percent more than that of control group, and then began to decrease, to it's minimum point at 24h. For 7 times, it increased continuously to it's summit at 24h, which was 230 percent more than that of control group. For 14 times, it attained it's peak at 0.5h,which was 197 percent more than that of control group, and then decreased gradully. At 24h, there was no significant difference between experiment and control group. For 21 times, it achieved it's summit at 0.5h, which was 388 percent more than that of control group, and then decreased, to it's minimum point at 12h, and rised again to 24h. * ngiotensin II in plasma of the rats exposed to infrasound with 130dB for once,10increased continuously to it's peak at 24h, which was 323 percent more than that of control group. For 7 times, it achieved it's peak at 12h, which was 229 percent more than that of control group, and then decreased, lower than that of control group at 24h. For 14 times, it increased significantly at O.Sh, but there was no significant difference between 6h and 12h, and then increased continuously to it's peak at 24h, which was 256 percent thanthat of control group. For 21 times, it began to increase at 0.5h, and reached it's peak at 12h, which was 167 percent more than that of control group, and then decreased, no significant difference between experiment and control group at 24h.Angiotensin II in hypothalamus of the rats exposed to 90dB infrasound for once, increased significantly at O.Sh, to it's peak at 12h, which was 530 percent more than that of control group, and then decreased, higher than that of control group at 24h. For 7 times, increased significantly at O.Sh, and then decreased, to it's minimum point at 12h, and increased significantly again, to it's peak at 24h, which was 487 percent more than that of control group. For 14 times, it achieved it's summit at O.Sh, which was 212 percent more than that of control group, and then decrease...
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