Unidirectional uptake of l-alanine and l-serine by system ASC in the basolateral membrane of cat salivary epithelium. Selective inhibition of rapid alanine metabolism by aminooxyacetate

Unidirectional influx of l-alanine and l-serine across the basolateral membrane of cat salivary epithelium was investigated in perfused submandibular glands using a rapid (<30 s) paired-tracer dilution technique. (Bustamante, J.C., Mann, G.E. and Yudilevich, D.L. (1981) J. Physiol. 313, 65–79). High uptakes were measured for both neutral amino acids, however, only the uptake of l-alanine was followed by an immediate tracer efflux into the circulation. Aminooxyacetate, an inhibitor of alanine aminotransferase, completely inhibited this efflux and glandular pyruvate production. These results demonstrate that in assessing unidirectional amino acid uptake, the influence of metabolism should be considered even during short intervals of measurement.