Effects of stress and of autonomic blockers on gastric mucosal microcirculation in rats

Changes in gastric mucosal microcirculation in rats were studied by using the method of intra-aortic injection of India ink, followed by microdissection of the mucosa. Acute stress, induced by restraint and exposure to cold for 2 hr, caused marked and significant vasodilatation in the gastric mucosa. This vasodilatation was prevented by pretreatment with atropine or chlorpromazine, but not by alpha- or theta-adrenoceptor blocking agents. Phentolamine caused significant vasoconstriction in the gastric mucosa of non-stressed rats, but when animals were stressed phentolamine induced a greater vasodilatation than was obtained with stress alone. These observations provide added support for the hypothesis that stress induces vagal overactivity, probably of central origin. The resulting strong contractions of the gastric wall, and compression of the intramural vessels, are probably responsible for degeneration of the mucosal cells leading to the formation of stress-induced ulcers in the rat.