[Effects of hydrocortisone on acid secretion in the isolated toad gastric mucosa].

The effects of steroids on gastric acid secretion have been studied in different animal species with contradictory results. In the present work we investigated direct effects of hydrocortisone on acid secretion in the isolated toad gastric mucosa (Bufo marinus). The rate of hydrogen ion secretion (QH+) was measured using the pH-stat method of Durbin and Heinz. Hydrocortisone significantly stimulated QH+ in a dose dependent manner. The effect tended to reach a maximum with the concentration of 10mM and lasted for at least one hour. In the mucosa pre-treated with 1mM cimetidine, an specific antagonist of histamine H2 receptors, the addition of 10mM hydrocortisone did not stimulate QH+, but addition of the cholinergic agonist carbachol did produce a significant stimulation in the rate of acid secretion. In the gastric mucosa previously stimulated with 5mM hydrocortisone, the addition of a submaximal dose of histamine increased QH+ and this effect was greater than that provoked by histamine in the absence of the steroid. The results indicate that hydrocortisone significantly stimulates acid secretion in a dose-dependent manner in the isolated toad gastric mucosa. This effect seems to be dependent on the activation of H2 receptors.