Concentrative PAH transport by rabbit kidney slices in the absence of metabolic energy

Abstract

Characteristics of p-aminohippurate (PAH) transport in the absence of intracellular metabolism were studied with Na+,K+-depleted and ouabain-poisoned rabbit kidney cortex slices. The imposition of a NaCl gradient (out to in) resulted in specific stimulation of PAH uptake. PAH accumulated against its concentration gradient when cell [Na+] was less than medium [Na+] conversely, renal cells exfroded PAH when cell [Na+] (exceeded medium [Na+]. Membrane potential measured with triphenylmethylphosphonium revealed that conditions which created an interior-positive membrane potential inhibited the Na+-dependent transport of PAH but caused stimulation of the Na+-independent component. Characteristics of the Na+-dependent PAH transport system in ouabain-poisoned slices were similar to those previously described in metabolically active tissues.