Role of blood flow in adaptive protection of the cat gastric mucosa.

This study was designed to test the hypothesis that adaptive cytoprotection is related to increased blood flow caused by mild irritants. The stomach of cats was perfused with saline at pH 1.0. Mucosal blood flow was determined by radioactive microspheres, and celiac artery blood flow was measured by Doppler ultrasound. Gastric blood flow was left undisturbed or reduced by tightening a vessel loop around the celiac artery. Mucosal exposure to absolute ethanol for 2 minutes caused extensive damage to the surface epithelium, the pits, and the upper half of the glands. Pretreatment of the mucosa with 2 mol/L NaCl for 10 minutes prevented the development of mucosal lesions after subsequent application of absolute ethanol. The mucosal blood flow increased markedly after treatment with 2 mol/L NaCl. When this hyperemic response was inhibited by reducing celiac artery blood flow, ethanol caused lesions of similar degree as in animals not pretreated with 2 mol/L NaCl. A highly significant correlation was obtained between mucosal blood flow, as determined just before the application of ethanol, and the degree of ethanol-induced damage. At a chosen level of blood flow, ethanol caused the same degree of damage with or without pretreatment with 2 mol/L NaCl. In conclusion, high mucosal blood flow caused by a mild irritant is an important factor in adaptive gastric protection. With the present experimental setup, the protection could be fully explained as a result of the hyperemic response caused by 2 mol/L NaCl.