The hemodynamic responses to venous pressure elevation and the effect of metabolic stimulation on reactive hyperemia and autoregulation were assessed in chambered segments of the canine gastric corpus perfused by a pressurized reservoir. Arteriovenous oxygen difference, mucosal pH, and total, mucosal, and muscularis blood flow were monitored continuously. Pentagastrin increased acid secretion, oxygen consumption, and both total and mucosal blood flow. Before and after pentagastrin, the magnitude of reactive hyperemia was correlated with the occlusion duration. During stepwise reductions in perfusion pressure, oxygen consumption was relatively constant and blood flow-independent over most of the pressure range. Mucosal blood flow was well maintained except at the lowest perfusion pressure. Pentagastrin did not enhance autoregulation in the mucosa or muscularis, but did enhance the autoregulation of total blood flow. A myogenic vasoconstriction occurred during 20-mmHg venous pressure elevations. Our results indicate that both metabolic and myogenic mechanisms regulate the gastric mucosal circulation.
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