The defensive role played by the gastric microcirculation.
Microcirculation plays an important role in the maintenance of functional integrity of the stomach and in the provision of its defense mechanisms against damage. Changes in blood flow in the gastro-duodenal mucosa, brought about by the local release of vasoactive or cytotoxic mediators, including free-radicals, the eicosanoids thromboxanes and leukotrienes, and the related phospholipid, PAF, have been implicated in the pathogenesis of various forms of peptic ulceration and erosive gastritis. Damage to microvessels and vascular endothelium leading to disruption of microcirculation is considered to be an initial event in the development of such lesions. Furthermore, preservation of microcirculation by prostaglandins is likely to make an important contribution to the overall protection of the gastric mucosa by these agents. Studies on the hemostatic mechanisms in the gastric mucosa indicate that bleeding is initially arrested by a coagulation process that is independent of platelet aggregation. Thus, the identification and characterization of microcirculatory events is of major importance in the understanding of pathophysiological processes in the gastric mucosa.