LOPERAMIDE BUT NOT MORPHINE HAS ANTI-SECRETORY EFFECTS IN HUMAN COLON, INVITRO

Isolated preparations of human colonic mucosa were set up in Ussing chambers. Noradrenaline reduced basal short-circuit current, morphine did not nor did loperamide except at the highest concentration tested. Electrically evoked increases in short-circuit current were unaffected by morphine but reduced by loperamide, by a naloxone-insensitive mechanism. Unidirectional fluxes of sodium-22 and chloride-36 were unaffected by morphine. It is concluded that loperamide but not morphine has an anti-secretory effect on human colonic mucosa.