Renal taurine transport--recent developments.

Abstract

The renal proximal tubule, with its brush border surface is the site of the active accumulation of all amino acids, including taurine (19). Following filtration at the glomeru-lus, taurine resides in the ultrafiltrate of plasma which passes by the apical or brush border surface of the tubule. As in many other biological membranes, the transfer of taurine across the brush border membrane is Na+-dependent (5,20) and requires external Cl− (6). This transport of taurine can best be studied by employing isolated renal brush border membrane vesicles (BBMV) which permit an evaluation of factors which influence the uptake of taurine both in vitro by changing the chemical composition of the incubation medium and in vivo by exposure of animals to various manipulations (4–5). Our group has been interested in establishing how renal amino acid transport mechanisms adapt to changes in the level of taurine or its precursors in the diet. To carry out these studies, a rat model has been used and the accumulation of taurine by BBMV has been measured.