Impairment of gastric microcirculation in stress.

Gastric mucosal blood flow and microvascular patterns were studied in normal and stressed rats. In addition, various regulating factors of gastric mucosal blood flow, such as autonomic nervous system and biogenic amines, were investigated by histochemical procedures. Gastric mucosal blood flow was determined by the hydrogen gas clearance method as well as the hydrogen gas electrolytic method, and the microvascular structure was observed by the infusion method with two-colored silicon rubber. The gastric mucosal blood flow decreased significantly in the early period after induction of burn stress. The incidence of acute gastric mucosal lesions had a highly correlative relation with the decrease in mucosal blood flow. Reduction of mucosal blood flow was consequently due to opening of an arteriovenous shunt and hyperpermeability of true capillaries. This hemodynamic change, regulated by biogenic amines and autonomic nerves, was followed by ischemia and congestion of the gastric mucosa. The results of these studies demonstrated the importance of defensive factors; that reduction of mucosal blood flow resulted in the sequence of events that led to formation of acute gastric mucosal lesions.