Electrochemical response patterns to histamine, bombesin, and pentagastrin in isolated bullfrog gastric mucosa

Histamine, bombesin, and pentagastrin produced different patterns of changes in short circuit current, electric conductance, potential difference, and acid secretion in isolated bullfrog gastric mucosa. Histamine produced a gradual increase in electric conductance, parallel to the increase in acid secretion, and a transient rise in short circuit current. Bombesin induced an abrupt increase in electric conductance and in short circuit current, which peaked after 8 minutes. Pentagastrin also produced an increase in short circuit current, which peaked after 8 minutes; electric conductance, however, rose more gradually. Bombesin produced only a short term increase in acid secretion. These experiments show that histamine, bombesin, and pentagastrin affect gastric mucosa by different mechanisms. Histamine may have a more pronounced effect on the fusion process and activation of the tubulovesicular system of the parietal cell; bombesin may act by transiently increasing the permeability of the basolateral membrane. Pentagastrin seems to have an effect on both the basolateral membrane and the tubulovesicular acid secretory apparatus. These observations are not consistent with the hypothesis that histamine is the final common mediator for the effects of other secretagogues.