Micropuncture study of tubular transport of urate and PAH in the pig kidney.
At physiological plasma urate concentration (Purate) (0.05 mg/dl), net secretion of urate occurred in the convoluted part of the proximal tubule of micropunctured anesthetized pigs. The fraction of filtered urate delivered to the point of micropuncture ((TF/P)urate/(TF/P)polyfructosan) was 4.8 +/- 0.5 (mean +/- SE, n =10). Urate was reabsorbed from lower tubular segments, since the fractional excretion of urate (FEurate) was only 2.1. Saturation of secretion as well as reabsorption occurred at Purate of 1.6 mg/dl. p-Aminohippurate (PAH) secretion also occurred mainly in the pars convoluta of the proximal tubule: (TF/P)PAH/(TF/P)polyfructosan was 4.0 +/- 0.4 (n = 11), whereas the FEPAH was 4.5 +/- 0.5 (n = 5). Thus, the pars recta does not contribute significantly to the net secretion of either urate or PAH. PAH was a competitive inhibitor of urate secretion. At a PPAH of 60 mg/dl there was overall net reabsorption of urate. Accordingly, in the pig PAH and urate seem to be secreted by the same transport mechanism.
D000042:Absorption; D000618:Aminohippuric Acids / Q000378:metabolism*; D000818:Animals; D001693:Biological Transport, Active; D005260:Female; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D012737:Sex Factors; D013045:Species Specificity; D013552:Swine / Q000378:metabolism*; D014527:Uric Acid / Q000378:metabolism*; D010130:p-Aminohippuric Acid / Q000378:metabolism*
D000618:Aminohippuric Acids; D014527:Uric Acid; D010130:p-Aminohippuric Acid