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 < 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 < 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 ml 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 (↑ IHB, ↓ ISO₂) precedes the development of gross mucosal ulcerations; and (3) the margin of the established ulceration in this model exhibits hyperemia (↑ IHB, normal ISO₂) which mimics that of a healing gastric ulcer.