ADAPTIVE PROTECTION RELATED TO CLEARANCE OF ETHANOL IN GASTRIC-MUCOSA OF CATS

This study was designed to test the hypothesis that hyperemia after exposure to 2 M NaCl protects the gastric mucosa against damage caused by absolute ethanol by removing ethanol diffusing from the gastric lumen into the mucosa. The stomach of anesthetized cats was perfused with saline at pH 1.0. Gastric mucosal blood flow was determined by radioactive microspheres, and portal vein blood flow was measured by Doppler ultrasound flowmetry. The concentration of ethanol in the corpus mucosa and the amount of ethanol transported away from the stomach in portal blood were measured by using absolute ethanol containing trace amounts of C-14-labeled ethanol. Pretreatment with 2 M NaCl for 10 min increased mucosal blood flow and prevented the development of deep mucosal lesions after subsequent application of absolute ethanol. An inverse correlation was found between mucosal blood flow and the degree of ethanol-induced damage. The mucosal content of ethanol was low in animals pretreated with hyperosmolar NaCl, and the degree of mucosal damage was related to the tissue concentration of ethanol. The amount of ethanol transported by blood from the stomach increased with increasing mucosal blood flow. We conclude that the mild irritant, 2 M NaCl, increases mucosal blood flow, which protects the mucosa by removing ethanol diffusing from the lumen. Thus, the mucosal ethanol concentration remains below a level that causes damage.