STUDIES ON RENAL URATE SECRETION IN THE DOG

¹ Departments of Environmental Health and Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio

An understanding of the mechanism of drug action on urate excretion requires selective study of unidirectional fluxes. We have utilized two techniques in an attempt to characterize the urate secretory flux in the dog. Results of double indicator dilution studies with ¹⁴C-urate and ³H-inulin indicate that less than 10% of the postglomerular urate is extracted from the inulin space. Since the size of this urate extraction imposes an upper limit on the magnitude of urate secretion, it follows that the secretory flux is relatively small. A rapid flux of ¹⁴C-urate from postglomerular blood into the tubular lumen was also demonstrated with a modified stop-flow technique. This flux could be inhibited by a number of agents, including p-aminohippurate, pyrazinoate, probenecid, chlorothiaside, furosemide, ethacrynate and lactate, but not by chlormerodrin. These data are further evidence that a number of similarities exist between drug effects on urate excretion in man and the dog.