EFFECTS OF PARA-AMINOHIPPURATE AND PYRAZINOATE ON THE RENAL EXCRETION OF SALICYLATE IN THE RAT - A MICROPUNCTURE STUDY

  • 1 January 1983
    • journal article
    • research article
    • Vol. 224  (2) , 451-458
Abstract
The inhibitory effects of p-aminohippurate and pyrazinoate (PZA) on the transport of salicylate were studied by free-flow micropuncture in the rat. p-Aminohippurate (5, 10 or 25 .mu.mol/kg.cntdot.min) and PZA (10 or 25 .mu.mol/kg.cntdot.min) inhibited proximal tubular secretion of salicylate; they induced decreases in the fractional delivery of salicylate to the late proximal tubules. In alkalotic rats, the late proximal decrease in fractional delivery of salicylate was accompanied by a decreased fractional excretion of salicylate. Such a decrease in fractional excretion of salicylate was not observed in rats in normal acid-base balance. A greater rate of PZA infusion (25 .mu.mol/kg.cntdot.min) not only inhibited secretion, but also depressed a reabsorptive carrier-mediated transport of salicylate. In alkalotic rats, fractional delivery of salicylate to late proximal tubules were 1.90 .+-. 0.15, 0.90 .+-. 0.10 and 1.34 .+-. 0.13, respectively, for control rats and rats infused with 10 or 25 .mu.mol/kg.cntdot.min of PZA. The corresponding values of fractional excretion of salicylate were 1.21 .+-. 0.09, 0.61 .+-. 0.05 and 0.08 .+-. 0.09, respectively. Salicylate apparently is secreted as well as reabsorbed by carrier-mediated mechanisms and there may be 2 secretory mechanisms.