Absorption of dissociated and undissociated short-chain fatty acids across the colonic epithelium of guinea-pig.
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.
Rönnau
K
K
Department of Physiology, School of Veterinary Medicine, Hannover, FRG.
Guth
D
D
von Engelhardt
W
W
D000818:Animals; D001692:Biological Transport; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000378:metabolism*; D004058:Diffusion; D004848:Epithelium / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000493:pharmacokinetics*; D006168:Guinea Pigs; D007408:Intestinal Absorption; D008297:Male; D010539:Permeability; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D005232:Fatty Acids, Volatile; D012964:Sodium