The reversal of bilirubin-induced intestinal secretion by agar

Agar binds bilirubin in vitro and lowers serum bilirubin concentrations by interrupting the enterohepatic circulation and increasing the fecal excretion of bilirubin. Nonconjugated bilirubin has been reported to induce secretion of sodium and water by the small intestine of perfused hamsters. We investigated the possibility that agar could prevent the secretory effect of bilirubin on hamster gut by sequestering it and reducing its enterocyte exposure. The small intestine of hamsters was luminally perfused in vivo with 0.5 mM bilirubin either alone or simultaneously with 0.15 g% agar. Control perfusions demonstrated luminal absorption of water and sodium in the absence of bilirubin. The inclusion of bilirubin resulted in secretion of sodium and water. The addition of agar to the bilirubin-infused animals resulted in net absorption of sodium and water comparable to that of controls. An additional agar-containing control perfusion demonstrated apparent secretion of sodium and water.