Absorption of short and medium chain fatty acids in the jejunum of the rat.

The uptake of the shortest six fatty acids (acetic to octanoic) was studied in vitro, using everted segments of rat jejunum. The marked influence of medium-pH and fatty acid chain-length suggests that non-ionic diffusion through the lipoid membrane is quantitatively the most important way of transport, but ionic diffusion through the membrane as well as transport through hydrophilic pores also seem to play a role. Though fatt acids evidently are accumulated in the tissue-fluid, and saturation kinetics, competitive inhibition and sodium- as well as energy-dependence apparently are observed, the transport mechanism is assumed to involve solely passive diffusion, - the concept of a carrier-mediated transport for short and medium chain fatty acids seems improbable.