ABSORPTION OF DISSOCIATED AND UNDISSOCIATED SHORT-CHAIN FATTY ACIDS ACROSS THE COLONIC EPITHELIUM OF GUINEA-PIG

¹ Department of Physiology, School of Veterinary Medicine, Bischofsholer Damm 15, D-3000 Hannover 1, FRG

Diffusion potentials for Na⁺, Cl^-, acetate (Ac^-), propionate (Pr^-) and butyrate (Bu^-) across the isolated epithelium of the proximal and the distal colon of guinea-pig were measured with flowing electrodes in Ussing chambers. Permeabilities of the anions are expressed in relation to the permeability of sodium. Unidirectional fluxes of Na⁺ and short-chain fatty acids (SCFAs) were estimated. Fluxes of SCFA anions and of undissociated SCFAs were calculated from relative permeabilities and flux values. In the proximal colon of guinea-pig 50% of SCFAs were transported in the dissociated and 50% in the undissociated form; transport rates of the three SCFAs were similar. In the distal colon SCFA transport was based primarily on diffusion of the free acids; the ratios of fluxes were: HAc/Ac^- = 2·4; HPr/Pr^- = 6·9; HBu/Bu^- = 9·3, and transport rates increased with chain length of the SCFA.

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				M. D. Fitch and S. E. Fleming Metabolism of short-chain fatty acids by rat colonic mucosa in vivo Am J Physiol Gastrointest Liver Physiol, July 1, 1999; 277(1): G31 - G40. [Abstract] [Full Text] [PDF]