The effect of various pathophysiologic states on oxygen availability and integrity of gastric mucosal surface epithelial cells will be studied employing a canine in vivo chambered stomach model. Intracellular oxygen tension and transmembrane potential difference, a measure of cellular metabolism, will be measured with an ultramicroelectrode technique. Plans for the coming year include studies to examine the effects of sepsis, topical bile salts, prostaglandins, and ischemic and hypoxic on availability of oxygen to mucosal cells and the possible role of cellular hypoxia in various pathophysiologic states of gastric mucosa. In addition we plan to perform histologic studies with cell markers to further validate the locus of sampling with the oxygen microelectrode technique and to correlate pathophysiologic observations with histopathologic changes.