Glucose and cation transport in rat jejunum, ileum and colon in vivo: control experiments, and effect of cationic surfactant.

Osmotically balanced solutions of glucose (0.5-300 mM) and sodium chloride, containing cetrimonium bromide (cetrimide, 0.8-4.1 mM), were instilled into the jejunum, ileum and colon of anaesthetized rats. Net transport of glucose, sodium and potassium was studied by their disappearance from, or accumulation into the intestinal lumen during 15 min incubation. Cetrimide caused the following shifts in normal jejunal and ileal glucose absorption: At low luminal glucose levels, absorption was strongly depressed and may be converted to net secretion. At intermediate levels, inhibition was less pronounced, and at high luminal glucose levels absorption was enhanced. Similar changes were seen in the colon. Furthermore, cetrimide caused a three-fold change in the regression lines relating net sodium fluxes to the initial sodium concentration: The lines became steeper, the correlation was improved and the sodium concentration value corresponding to zero net transport was elevated. Net potassium secretion was increased. These changes are all consistent with the view that surfactants cause an increase in passive permeability. Quantitatively, the effect of cetrimide increased with localization in the order colon greater than ileum greater than jejunum. Benzalkonium chloride (0.5-1.7 mM) was tested in the ileum only, and caused quite similar effects.