AJP - Renal Physiology, Vol 239, Issue 3 222-F227, Copyright © 1980 by American Physiological Society
Accumulation of [14C]urate and [3H]PAH in isolated proximal tubular segments of the rabbit kidney
C. Schali and F. Roch-Ramel
Segments of rabbit proximal tubules (S1, S2, and S3) were incubated (30
min, 37 degrees C, pH 7.4) in Ringer solution (under O2) containing
[14C]urate or [3H]PAH and probenecid, pyrazinoic acid (PZA), urate, or PAH,
all at 1 mM. The ratio [14C]urate (counts/min per nanoliter of tubular cell
water)/(counts/min per nanoliter of incubation medium) (T/M) reached 2.92
+/- 0.31 (mean +/- SE; n = 15), 6.08 +/- 0.42 (n = 42), and 1.72 +/- 0.31
(n = 14) for S1, S2, and S3 segments, respectively. In these segments the
uptake of [3H]PAH was 22.7 +/- 4.6 (n = 19), 133 +/- 18.9 (n = 24), and
66.2 +/- 15.3 (n =0). The accumulation of [14C]urate was saturated at 2 x
10(-4) M in the medium, and that of [3H]PAH at 7 x 10(-5) M in the medium.
Secretory transport was saturated at the same bath PAH concentration in
perfused tubules. Urate and PAH transports inhibited each other, thus
suggesting a common transport mechanism mainly located in the S2 segment.
Probenecid was a strong and PZA a weak inhibitor of this transport system.
