Oxygen Metabolites in Immune- Stimulated Ion Transport in Rat Colon: Modulation by Taurine

Abstract

Background/Aims: Activation of cells within the lamina propria can cause electrogenic chloride secretion across intestinal epithelia by release and/or synthesis of mediator molecules, including reactive oxygen metabolites (ROMs). In this investigation we examined whether indirect (immune) stimulation of ion transport across rat colon was ROM-mediated. Methods: Paired segments of rat colon, stripped of underlying smooth muscle, were mounted on Ussing chambers in order to measure electrogenic ion transport. Changes in short circuit current (SCC) were used as a measure of net electrogenic ion transport measured in response to the bacterial tri-peptide formyl-Met-Leu-Phe (fMLP) which was used to activate lamina propria neutrophils. The effect of the established anti-oxidants catalase and diethyldithiocarbamate (DDTC) and the putative anti-oxidant taurine upon immune-stimulated ion transport was examined. Results: The anti-oxidant DDTC but not catalase significantly attenuated ion transport responses to fMLP. Taurine applied basolaterally reduced ion transport response to fMLP but not to the directly acting secretagogues forskolin. Taurine applied apically enhanced ion transport responses to fMLP. Conclusion: Anti-oxidants, including taurine, may be useful in treatment of colitis. The enhancement of effect seen when taurine was applied apically may have negative implications regarding the therapeutic usefulness of taurine administration to the lumenal compartment.