Studies on the increased absorption of ouabain,phenolsulphonphthalein and pralidoxime caused by sodium lauryl sulphate from single loop preparations in the rat

Summary In concentrations above the critical micelle concentration (effective range about 2 mM to about 22 mM) sodium lauryl sulphate caused graded increases in the absorption of ouabain, phenolsulphonphthalein and pralidoxime from jejunal loops in anaesthetized rats. The surfactant-caused increases in the absorption of phenolsulphonphthalein and pralidoxime were significantly reduced if the sodium chloride of the medium was replaced by mannitol, respectively sucrose, or by sodium phosphate, and also if ouabain was added to the medium. The extent in absorption in the absence of surfactant was not altered. The surfactant-caused increase in the absorption of ouabain was not reduced by the mentioned sodium chloride exchanges in the medium. It is suggested that the increased absorption caused by sodium lauryl sulphate must be ascribed to a direct effect on the intestinal membrane. The results indicate some kind of Na-dependence for the increase in absorption observed for phenolsulphonphthalein and pralidoxime. Additional studies are in progress to further elucidate the observations mentioned.