Body temperature dependent decrease of gastric blood flow in restraint and water-immersion stressed rats.

The effects of restraint and water-immersion stress (RWIS) on the cardiovascular system (including blood pressure, heart rate, blood flow in the gastric region, and blood flow in the common carotid artery and descending aorta) and body temperature were studied in rats. The blood pressure of RWIS rats did not differ from that of restraint stress (RS) rats. The heart rate, blood flow in the gastric region, common carotid artery and descending aorta as well as body temperature were significantly decreased by RWIS, but not by RS. The decrease in heart rate in RWIS rats was not influenced by pretreatment with atropine, hexamethonium or vagotomy. The reduction of gastric regional blood flow was not influenced by pretreatment with atropine and phenoxybenzamine. The changes in these three parameters were closely correlated in all the RWIS rats tested. These results suggest that the decrease in gastric regional blood flow is due to a lowering of the body temperature via decreasing cardiac output.