Stopped-flow microperfusion studies of urate absorption from the rat proximal tubule.

Abstract

AbstractThe absorptive flux of [2-14C]urate in the rat proximal tubule was examined using stopped-flow and continuous-flow microperfusion techniques. In the stopped-flow studies, the luminal perfusion was a steady-state equilibrium solution and the luminal contact time was 60 sec. The ratio of disintegrations per minute (dpm) of urate in the reaspirated sample to the initial solution (C/I) was 0.42 ± 0.02 in control experiments. The addition of either phloridzin or ρ-chloromercuribenzoate to the perfusion solution resulted in significantly higher C/I ratios of 0.52 ± 0.03 (P < 0.05) and 0.61 ± 0.006 (P < 0.01), respectively. Substitution of choline for sodium in the perfusion solution or the addition of probenecid did not significantly change the C/I ratio. In continuous-flow microperfusion studies, the fractional absorption of urate from an isotonic saline solution averaged 10.2 ± 0.8%/mm tubule and was significantly inhibited by the addition of probenecid to the perfusion solution. Urate absorption from...