Effect of in vivo administration of parathyroid hormone on amino acid transport in membrane vesicles prepared from rabbit kidney tubules.

It has been postulated that high concentrations of parathyroid hormone might increase transport of amino acids across basal lateral membrane into the cell and that the amino-aciduria seen in hyperparathyroidism occurs because of leakage across brush border membrane into the lumen. Accordingly, we separated plasma membranes from renal proximal convoluted tubules into basal lateral and brush border fractions, both of which form vesicles. We found that for the vesicles from rabbits pretreated with parathyroid hormone, 14C-L-alanine incorporation was indeed enhanced in the basal lateral fraction, but not in the brush border fraction. Nor was significant enhancement found for vesicles from rabbits pretreated with cycloheximide in addition to hormone. We conclude that L-alanine uptake is greatest in the basal lateral membrane fraction after parathyroid hormone treatment in vivo. In such case, the two membranes also differ from each other in endocrine response.