Na+-gradient-dependent stimulation of renal transport of rho-aminohippurate.

Transport of rho-aminohippurate was studied by the use of a preparation of rabbit kidney basolateral-membrane vesicles and in rat kidney-cortex slices under anaerobic conditions. With both preparations clear evidence of Na+-gradient stimulation of rho-aminohippurate transport ('overshoot') was obtained. These results thus indicate that a significant aspect of active rho-aminohippurate transport is by co-transport with Na+, and they appear to resolve previous disagreements concerning the role of Na+. Vesicle studies with a potential-sensitive dye suggested that rho-aminohippurate may be transported electroneutrally, i.e. in a 1:1 complex with Na+.