Effects of PGE2 and colchicine on the intestinal fluid volume.

a) Colchicine, prostaglandin E2 (PGE2) and carbachol increase the intestinal fluid volume in the rat. b) The effect of carbachol and prostaglandin E2 is augmented whereas that of colchicine is diminished in the pithed rat. c) The effect of colchicine is diminished in anaesthesia whereas that of PGE2 remains unchanged. d) The effect of PGE2 and of colchicine are both inhibited by atropine. e) The effects of PGE2 and of colchicine are both enhanced by phentolamine. f) Pretreatment with indomethacin decreased the effect of colchicine whereas that of PGE2 remained unchanged. g) The PGE2-induced increase in intestinal fluid volume may partly be mediated by a peripheral mechanism involving acetylcholine receptors. h) The increase in intestinal fluid volume by colchicine can mainly be explained by a central action of the drug which is mediated by cholinergic neurones.