RENAL HANDLING OF [ALLANTOIN-C-14 IN THE RABBIT

  • 1 January 1980
    • journal article
    • research article
    • Vol. 213  (1) , 168-172
Abstract
Rabbit renal cortical slices were incubated at 25.degree. C, pH 7.4, for 2 h under 100% O2 in a phosphate-buffered medium. [14C]allantoin was accumulated to a tissue water/medium ratio of 1.38 .+-. 0.03 (mean .+-. S.E., n = 22). Under 100% N2, the tissue water/medium ratio fell significantly to 0.90 .+-. 0.02. Probenecid (an anion) inhibited the uptake of allantoin [AT] at doses which had no effect on the water content of the slices, i.e., did not appear to have a toxic effect on the tissue. Its effect was specific. In contrast, salicylate (another anion) and quinine (a cation) inhibited the uptake of AT only at concentrations which simultaneously increased the water content of the slices. These results suggest a toxic effect on cell metabolism. Salicylate and quinine in dosage which inhibited AT uptake, also inhibit the uptake of the para-aminohippuric acid (an anion) and tetraethylammonium bromide (a cation). Net secretion of AT was observed in urinary clearance experiments on anesthetized rabbits acutely loaded with AT, under mannitol diuresis. At flow rates < 1 ml/kg.cntdot.min, fractional excretion of [14C]AT was 0.85 .+-. 0.03 (n = 27 clearance periods) indicating significant net reabsorption. When urine flow was increased above 1 ml/kg.cntdot.min, fractional excretion of [14C]AT reached 1.07 .+-. 0.03 (n = 18 clearance periods), i.e., net secretion.

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