Body temperature dependency of gastric regional blood flow, acid secretion and ulcer formation in restraint and water-immersion stressed rats.

The effect of water temperature during restraint and water-immersion stress (RWIS) on gastric regional blood flow, acid secretion and ulcer formation were compared to those of restraint stress (RS) alone in rats. RS had no effect on the gastric regional blood flow. In contrast, the gastric regional blood flow was significantly decreased by RWIS. A water temperature dependent reduction of gastric regional blood flow induced by RWIS was observed between 20 degrees C and 30 degrees C. The decrease in gastric regional blood flow for RWIS rats was related to a lowering of the body temperature, which almost coincided with the temperature of water for the immersion. The gastric acid output was not influenced by RS. However, RWIS significantly increased the gastric acid output. The temperature of water in order of increasing acid output induced by RWIS was 25 degrees C greater than 30 degrees C greater than 20 degrees C. Little ulcer formation was found in RS rats, while exposure to RWIS caused marked ulceration. The temperature of water in order of severity of ulceration by RWIS was 25 degrees C greater than 20 degrees C greater than 30 degrees C. The severity of ulceration was not related to the decrease in gastric regional blood flow or increase of acid output, but was correlated to the ratio of the gastric blood flow/the acid output. These findings suggest that the decrease of gastric regional blood flow is in good agreement with the fall of body temperature, and the combined effects of the gastric blood flow and the acid secretion are involved in the ulceration caused by RWIS.