INCREASED EX-VIVO COLONIC GENERATION OF PAF INDUCED BY DIPHENYLMETHANE STIMULANT LAXATIVES IN RATS, MICE, GUINEA-PIGS AND RABBITS

The effects of in-vivo treatment with bisacodyl, phenolphthalein, pico sulphate, sulphosuccinate, mannitol and lactulose laxatives were exami ned on the ex-vivo formation of platelet-activating factor (PAF) by du odenum and colon of rat, mouse, guinea-pig and rabbit. Bisacodyl (10 m g kg-1), phenolphthalein (20 mg kg-1) and picosulphate (10 mg kg-1), b ut not sulphosuccinate (40 mg kg-1), mannitol (50 mg kg-1) or lactulos e (50 mg kg-1), at doses that all caused laxation, markedly increased PAF in the colon (P<0.01) but not in the duodenum. Intraluminal releas e of acid phosphatase was also significantly increased in the colon of rats treated with bisacodyl, phenolphthalein and picosulphate, but no t in colons of animals treated with sulphosuccinate, mannitol or lactu lose. The data show that enhanced generation of PAF is associated with the colonic damage induced by diphenylmethane laxatives, but do not s how whether this is a cause or a consequence of the pathophysiological changes.