The renal accumulation of urate and p-aminohippurate in the rabbit

1. During intravenous infusion of urate and p-aminohippurate (PAH), the concentration of these two substances in cortex tissue of rabbit kidney exceeded the corresponding plasma concentration.2. Following the administration of 2,4-dinitrophenol, fumarate, succinate, probenecid, and salicylate, accumulation of urate in kidney cortex and renal net secretion of urate were abolished. The accumulation and secretion of PAH were only partially inhibited after infusion of these compounds.3. The renal accumulation of urate was reduced in relation to the inhibition of urate excretion during infusion of various amounts of PAH.4. The combined data indicate a correlation between renal accumulation and excretion of urate and PAH. It appears likely that accumulation of urate and PAH in vivo is due to tubular secretion of these two substances, although in the case of urate a small contribution from tubular reabsorption of urate cannot be excluded.

The relation between secretion of urate and p-aminohippurate in the rabbit kidney

1. The renal excretion of urate in the rabbit was examined during infusion of other anions which are secreted by the kidney. A reduction of urate excretion occurred after administration of p-aminohippurate (PAH) and Diodrast which was proportional to the secretory rate of these compounds. On the other hand, urate was a less efficient inhibitor of PAH secretion.2. Stop-flow experiments showed that tubular secretion of urate at maximal values for secretion of PAH and Diodrast was almost completely suppressed.3. 2,4-Dinitrophenol, fumarate, succinate, salicylate, and probenecid depressed the excretion of urate and PAH, but the tubular secretion of urate was apparently more depressed than that of PAH by these inhibitors.4. It is concluded that a common transport system for urate and PAH is involved in the tubular secretion of urate and PAH in the rabbit. However, the affinity of urate for the transport system appears to be smaller than that of PAH.