Effect of bisacodyl on the uptake of monosaccharides by isolated enterocytes

Diphenolic laxatives are known to alter nutrient absorption and secretion in the small and large intestine. We have studied the effect of 0.75 mM bisacodyl on sugar transport in isolated chicken intestinal epithelial cells. Results show that (1) bisacodyl inhibits Na+-dependent alpha-methyl-glucoside (alpha-MG) accumulation by 45% after 40-minute incubation. (2) The drug reduces initial (1 minute) alpha-MG influx by 60%. This effect is much lower than that exerted by 0.15 mM phlorizin (90% inhibition). (3) Bisacodyl also reduces Na+-independent sugar flux through the basolateral membrane since initial 2-deoxy-glucose influx is reduced 67% by the drug. The effect of the drug on this pathway is lower than that exerted by theophylline (7.5 mM). The addition of bisacodyl or theophylline (plus 20 microM phlorizin to inhibit the apical sugar transport system) to cells preloaded with 3-oxy-methyl-glucose allowed calculation of the initial sugar efflux rate. This was found to be lower after theophylline addition than after the addition of bisacodyl, thus confirming that bisacodyl exerts an incomplete inhibition of the Na+-independent sugar transport system. It is concluded that the direct effects of bisacodyl on both apical and basolateral sugar transport pathways may explain in part the inhibitory effects of the drug on the intestinal absorption of sugars.