Ho M M, Ogle C W, Dai S
Pharmacol Res Commun. 1985 Sep;17(9):855-64. doi: 10.1016/0031-6989(85)90044-x.
The influence of morphine on acid secretion by the isolated gastric mucosa was studied in adult rats. A wide range of morphine concentrations (1 X 10(-4) to 1.6 X 10(-3) M) was found to have no effect on basal acid output, or on acid secretion maximally stimulated by bethanechol or histamine. It is suggested that the opiate receptors in the rat gastric mucosa, if there are any, are not involved in modulating acid secretion.