Butyrate Hastens Restoration of Barrier Function after Thermal and Detergent Injury to Rat Distal Colon in Vitro

Abstract

Background: Epithelial migration restores barrier function after superficial injury to any mucosa. The present study aimed to determine whether butyrate, important to colonic epithelial physiology in diverse ways, influences restoration of barrier function in the injured rat colon. Methods: Rat distal colon was transiently exposed in vitro to heat (55°C for 10 sec) or to detergent (deoxycholic acid, 7.5 mM, for 15 min), and tissue damage was verified histologically. Epithelial barrier function was assessed, in colon tissue mounted in Ussing chambers, by measuring electric resistance and passive serosa-to-mucosa fluxes of ²²Na and of ¹⁴C PEG 4000 under voltage clamp conditions. Studies were done in the absence and presence of 25 mM butyrate in the bathing solutions. Results: Heat exposure induced superficial epithelial damage, and the electric resistance decreased significantly. This was accompanied by increase in flux of­¹4C PEG and increased passive flux of 22Na. Electric resistance was significantly higher, and PEG flux significantly lower, in tissues bathed with butyrate. Exposure to deoxycholic acid also induced superficial epithelial damage, reduced tissue electric resistance, and increased passive flux of Na and PEG. Electric resistance was significantly higher, and PEG flux significantly lower, in injured tissues bathed in butyrate, than in injured tissues bathed in butyrate-free solution. The effect of butyrate on restoration of electric resistance towards normal was seen in colon both from adult rats and from younger rats that were 2 or 6 weeks old. Conclusions: Butyrate enhanced restoration of mucosal barrier function in rat distal colon in response to heat and detergent injury.