Studies of the antisecretory activity of morphine in rabbit ileum in vitro.

We studied the influence of morphine on intestinal secretion induced by three different secretogogues in an attempt to elucidate the mechanism for its antisecretory activity. In rabbit ileal mucosa in vitro morphine (10(-4) M) did not influence the electrical response to the subsequent administration of prostaglandin E2 or of acetylcholine but did inhibit the net secretion of chloride provoked by both agents and prevented the reduction of sodium adsorption induced by the prostaglandin. Morphine reduced the peak electrical response to cholera toxin and reduced toxin-induced net chloride secretion. The modes of action of morphine appeared to be by both enhancing adsorption, as it does in control, nonsecreting mucosa, and by inhibiting secretogogue activity.