Developmental aspects of renal beta-amino acid transport I. Ontogeny of taurine reabsorption and accumulation in rat renal cortex

Newborn Sprague-Dawley rat pups were found to have reduced net tubular reclamation of the beta-amino acid taurine in vivo. The reabsorption of this compound increased between the 2nd and 4th week of life and the excreted taurine fell despite a rise in glomerular filtration rate indicative of increased transport with maturation. Kidney cortex in vivo accumulated taurine from plasma against a large chemical gradient. Newborn cortex slices in vitro accumulated taurine to higher levels at steady state at less than 0.4 mM, but uptake was less efficient at higher taurine concentrations. Further metabolism of taurine by cortex slices was not found at any age. Accumulation in adult and newborn cortex was greatest at 10-15 mEa/liter K in the external medium. Slices from younger animals had slightly higher pH optima for uptake and temperature elevation increases uptake more in neonatal than in adult kidney.