Rönnau K, Guth D, von Engelhardt W
Department of Physiology, School of Veterinary Medicine, Hannover, FRG.
Q J Exp Physiol. 1989 Jul;74(4):511-9. doi: 10.1113/expphysiol.1989.sp003298.
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.
采用乌斯电极室中的流动电极，测定了Na⁺、Cl⁻、乙酸根（Ac⁻）、丙酸根（Pr⁻）和丁酸根（Bu⁻）跨豚鼠近端和远端结肠分离上皮的扩散电位。阴离子的渗透率以相对于钠渗透率的形式表示。估算了Na⁺和短链脂肪酸（SCFAs）的单向通量。根据相对渗透率和通量值计算了SCFA阴离子和未解离SCFAs的通量。在豚鼠近端结肠中，50%的SCFAs以解离形式运输，50%以未解离形式运输；三种SCFAs的运输速率相似。在远端结肠中，SCFA的运输主要基于游离酸的扩散；通量比为：HAc/Ac⁻ = 2.4；HPr/Pr⁻ = 6.9；HBu/Bu⁻ = 9.3，且运输速率随SCFA链长增加而增加。
