Effect of explosive noise on gastrointestinal transit and plasma levels of polypeptide hormones

To investigate the effect of firing noise on gastrointestinal transit and probe its mechanism by measuring the levels of plasma polypeptide hormones. A total of 64 SD rats were randomly divided into a control group and three stimulating groups. Firing noise of different intensity by sub-machine guns was used as inflicting factor. The effect of firing noise on liquid substance gastrointestinal transit and solid substance gastrointestinal transit was observed by measuring the ratio of carbon powder suspension transmitting and barium sticks transmitting respectively. Plasma levels of polypeptide hormones were measured by radio-immunoassay. The noise accelerated gastrointestinal transit of solid food by more than 80 db;and accelerated gastrointestinal transit of liquid food significantly by more than 120 db. Meantime, plasma levels of plasma motilin (MTL)(157.47+/-16.08; 151.90+/-17.08), somatostatin (SS)(513.97+/-88.77; 458.25+/-104.30), substance P (SP)(115.52+/-20.70; 110.28+/-19.96) and vasoactive intestinal peptide (VIP) (214.21+/-63.17; 251.76+/-97.24) remarkably changed also. Within a certain intensity range, the firing noise changes the levels of rat plasma gastrointestinal hormones, but the gastrointestinal transit is still normal. Beyond the range, the noise induces plasma hormone levels disturbance and gastrointestinal transit disorder.