Role of Histamine and Calcitonin Gene-related Peptide in the Hyperemic Response to Hypertonic Saline and H+ Back-Diffusion in the Gastric Mucosa of Cats

Background: The present study was undertaken to measure the output of histamine and calcitonin gene-related peptide (CGRP) from injured and restituting gastric mucosa into venous blood and to study the effect of acid back-diffusion on the release of these mediators and their role in the hyperemic response to injury. Methods: Stomachs of cats were perfused with saline at pH 1.0 or 7.4. Gastric mucosal blood flow (GMBF) was determined with radioactive microspheres, and blood flow in the portal vein and celiac artery was determined by transit-time flowmetry. H+ back-diffusion/secretion was measured by pH-stat titration and by measuring the arteriovenous base excess difference. Mucosal injury was produced by exposure to 2 M NaCl. Histamine and CGRP in portal venous blood were measured by radioimmunoassay. Results: During mucosal exposure to 2M NaCl GMBF increased, and histamine (0.23 nmol/min) and CGRP (1.2pmol/min) were released from the mucosa into blood. The hyperemic response was reduced by pretreatment w...