Studies of organic anion and cation transport in isolated segments of proximal tubules

Abstract

The transport of organic anions and cations has interested physiologists for many years despite the generally held view that these transport mechanisms are involved principally in the elimination of foreign substances and metabolites from the body. The clearance and excretion of para-aminohippurate (PAH) has been used an an index of renal plasma flow, and the maximal rate of PAH secretion has been assumed to reflect the mass of functioning renal tissue in patients [1]. Clinicians also utilize the fractional excretion of urate as a guide to volume sufficiency of the extracellular fluid compartment and quantify the excretion rate of this organic solute in the evaluation of gout and urolithiasis [2]. The renal excretion of organic cations has been of principal interest to renal pharmacologists, although there is increased awareness among clinicians that this system is important in the regulation of endogenous levels of organic bases [1].