Absorption of pantothenic acid in rat and chick intestine

Abstract

Pantothenic acid absorption was evaluated in the intestine of rat and chicken to reevaluate the concept that this nutrient crosses the mucosa by simple diffusion. Unidirectional influx of [3H]pantothenic acid (0.9 microM) across the brush-border membrane of rat jejunum in vitro demonstrates sodium dependence and saturation kinetics. Net transepithelial transport (absorption) of pantothenic acid takes place in everted sacs of jejunum against an electrochemical potential gradient. This accumulation does not occur in tissue exposed to metabolic inhibitors. Also, pantothenic acid accumulates in the transport cells of both rat and chicken intestine against a 9- to 10-fold concentration gradient. Recently absorbed pantothenic acid is freely diffusible from isolated chicken enterocytes. No metabolic conversion of pantothenic acid was detected during absorption in the intestine of either species under conditions in vitro or in vivo. The present results indicate that pantothenic acid present at low concentrations is absorbed in the intestine by a specific transport mechanism; the process is best described as sodium-dependent, secondary active transport.