Active absorption of vitamin B12 and conjugated bile salts by guinea pig ileum occurs in villous and not crypt cells

Abstract

We isolated highly enriched fractions of villous and crypt cells from guinea pig intestine to determine whether this preparation provided a suitable model for comparing the transport of cobalamin and conjugated bile salts by these cell populations. The uptake of [57Co] cyanocobalamin by ileal villous cells was 30-fold greater when incubated with cobalamin bound to intrinsic factor than with free cobalamin. Intrinsic factor-mediated uptake of cobalamin could not be demonstrated using ileal crypt or jejunal villous or crypt cells. When incubated with [3H] taurocholate, the uptake by ileal villous cells was significantly greater than by ileal crypt or jejunal villous cells. These results indicate the suitability of using isolated guinea pig villous and crypt cells to examine transport processes of molecules that involve specialized mechanisms. The results also demonstrate that the undifferentiated crypt cell lacks specific transport processes necessary for the active absorption of cobalamin and taurocholate.