Endoscopic assessment of mucosal hemodynamic changes in a canine model of gastric ulcer.

In studying the side effects of sclerosants injected into the gastric submucosa in dogs (N = 7), we noted that 3 ml of absolute ethanol induced a large gastric ulceration. We describe the time course of change in the ulcer size, and suggest that such ulceration can be used for the endoscopic assessment of factors important in ulcer genesis and healing. Endoscopic reflectance spectrophotometric measurement of indices of mucosal hemoglobin concentration (IHB) and oxygen saturation (ISO2) were performed in a separate group of dogs (N = 4) with ethanol-induced gastric ulceration. We found a significant difference (p less than 0.05) in IHB and ISO2 immediately before (97 +/- 8 and 37 +/- 3, respectively) and after (138 +/- 7 and 21 +/- 5, respectively) the ethanol injection. At 24 hours after the ethanol injection, the IHB at the lesion margin (141 +/- 14) was significantly higher (p less than 0.05) than that at the adjacent mucosa (101 +/- 4), whereas the ISO2 measurements were not significantly different in these two locations, 34 +/- 2 and 31 +/- 2, respectively. We conclude that (1) injection of 3 mol of absolute ethanol into the submucosa of the canine stomach provides an animal model of gastric ulceration in which the ulcer can be examined repeatedly with the aid of the endoscope; (2) in this ulcer model, ischemia with congestion (increases IHB, decreases ISO2) precedes the development of gross mucosal ulcerations; and (3) the margin of the established ulceration in this model exhibits hyperemia (increases IHB, normal ISO2) which mimics that of a healing gastric ulcer.