The Transport of Urate in the Small Intestine of the Rat

Abstract

Abstract

The transport of urate in the small intestine of the rat was examined, in vivo, to determine if specific (mediated) transport systems are present. The secretory flux of urate was determined following the infusion of urate systemically, with or without oxanate, while the small intestine was perfused with an initially urate-free solution. The absorptive flux of urate was determined by perfusing the gut with solutions of known concentrations of urate. In some studies probenecid was infused systemically or added to the luminal perfusion solution. Over a wide range of concentrations of urate in the plasma or in the lumen, there was no evidence for saturation of either the secretory or absorptive fluxes of urate. Probenecid had no effect on either of the flux rates. These findings suggest that in the small intestine of the rat, the movement of urate out of or into the lumen occurs by passive diffusion and that, under the conditions of study, no evidence for facilitated transport can be demonstrated.