Intestinal ischemia-reperfusion increases efflux for uric acid via paracellular route in the intestine, but decreases that via transcellular route mediated by BCRP.J Pharm Pharm Sci. 2012; 15(2):295-304.JP
Uric acid is thought to be one of the most important antioxidants in human biological fluids. Intestinal ischemia-reperfusion (I/R) is an important factor associated with high rates of morbidity and mortality. Reactive oxygen species (ROS) are responsible for intestinal I/R injury. The aim of this study was to clarify the efflux for uric acid from the intestine after intestinal I/R.
We used intestinal ischemia-reperfusion (I/R) model rats. Serosal to mucosal flux for [¹⁴C]-uric acid was assessed by using Ussing-type diffusion chambers. BCRP/Bcrp expression was assessed by Western blot analysis. Caco-2 cells were used for a model of the intestinal epithelium, and rotenone was used as a mitochondrial dysfunction inducer.
Serosal to mucosal flux for uric acid was increased after intestinal I/R, and that for mannitol was also increased. Ko143, which is a BCRP inhibitor, did not affect the uric acid transport. The decreasing uric acid transport mediated by Bcrp was caused by decrease in the level of Bcrp homodimer, bridged by an S-S bond. The suppression of Bcrp S-S bond formation was associated with mitochondrial dysfunction. Moreover, BCRP S-S bond formation activity was decreased by rotenone in Caco-2 cells.
Serosal to mucosal flux for uric acid is significantly increased via the paracelluler route, but that via the transcellular route mediated by Bcrp is decreased after intestinal I/R. The decreasing uric acid flux mediated by Bcrp is caused by suppression of Bcrp S-S bond formation. This suppression of Bcrp S-S bond formation may be related to mitochondrial dysfunction.