Kinetics of p-aminohippurate secretion in the rabbit

¹ May Institute for Medical Research, Cincinnati Jewish Hospital, and Department of Physiology, University of Cincinnati College of Medicine, Cincinnati, Ohio

A technique is proposed and tested which permits the calculation of the size and turnover rate of the p-aminohippurate (PAH) secretory pool in the renal cortex of the rabbit in vivo. The secretory pool is here defined as the cellular solute compartment with which secreted solute equilibrates during its transcellular movement from plasma into tubular urine. The calculations are based on the rate of isotopic equilibration of plasma and urine under steady-state conditions. From the influence of various drugs on the characteristics of the secretory pool, it is inferred that 1) similar PAH carrier mechanisms mediate influx into, and outflux from, the secretory pool, and 2) the PAH accumulated within the cells is coextensive with the secretory pool and is present in a free rather than bound form.

Key Words: Benemid • Diodrast • renal cortex • renal secretory mechanism

Submitted on May 6, 1963