ROLE OF GASTRIC-ACID SECRETION AND BLOOD-FLOW IN THE DEVELOPMENT OF VAGAL-STIMULATION INDUCED GASTRIC-MUCOSAL DAMAGE

Vagal stimulation has been shown to result in the development of gastr ic mucosal erosions in the rat, although the mechanisms underlying the development of such erosions are not known. The effects of vagal stim ulation on gastric acid secretion and mucosal blood flow were examined in urethane-anesthetized male Sprague-Dawley rats to determine whethe r changes in these factors correlate with the mucosal damage in respon se to vagal stimulation. Electrical stimulation (5 Hz, 5 V, 1 ms for 6 0 min) of afferent or efferent components of the vagi was not found to induce any significant increase in the mean acid secretory rate compa red with control animals (p > 0.05). In contrast, stimulation of intac t vagus nerves induced a significant increase in the mean acid secreto ry rate compared with control and efferent- and afferent-stimulated gr oups (p < 0.01). Measurement of gastric blood flow with laser-Doppler flowmetry demonstrated intact vagal stimulation to have no significant effect on gastric blood flow. These data suggest that such vagal stim ulation induced increases in acid secretion in urethane-anesthetized a nimals may represent a part of the integrated physiological response t o such stimulation which leads to the development of gastric mucosal e rosions within 60 min. Pretreatment with antisecretory agents such as cimetidine and interleukin-l beta significantly reduce the gastric muc osal injury compared with untreated animals (p < 0.05), emphasizing th e important role of acid secretion in the development of vagal-induced gastric damage.