The Effects of Infrasound on Pituitary Adrenocortical Response and Gastric Microcirculation in Rats

Abstract

To clarify the effects of infrasound on the body, rats were exposed acutely to infrasound. Responses of the pituitary adrenocortical system of the rats to infrasound were evaluated with their frequency characteristics according to changes of the plasma ACTH and corticosterone (corti.) concentrations. The gastric mucosal blood flow of rats was determined by the inhaled hydrogen gas clearance method, and changes in the microcirculation of the gastric mucosa by infrasound were evaluated. The frequency characteristics of the responses of the rat pituitary adrenocortical system were parallel to, and about 30 dB above, the threshold of sensation in the humans, and corresponded to about 80 phon on the equal-loudness curves. The gastric mucosal blood flow of the rats exposed to 16 Hz infrasound at 120 dB for 20 minutes was significantly reduced by 19.1% (p<0.01) 10 minutes after the beginning of the exposure as compared with the pre-exposure level. The percent changes of the bood flow were significantly smaller (p<0.01) in the exposure group 10 minutes after the beginning, and 10 minutes after the end, of the exposure than in the control group. From the results above, it seems probable that exposure to infrasound might influence the endocrine system and even autonomic nervous system.