Fig. 1. Representative plot of unidirectional and net urate fluxes across chick PTCs as a function of time. The unidirectional fluxes include the interstitial-to-luminal secretory flux (secretory) and luminal-to-interstitial reabsorptive flux (reabsorptive; shown negative to indicate direction). Net flux is the difference between unidirectional fluxes. (A) Paired controls; (B) probenecid (1 mmol l^–1) added to interstitial and luminal sides at t=0. Fluxes approached steady state at t=1.0 h.