Disorders of Renal Amino Acid Transport

Abstract

During the past several decades our conception of plasma-cell membranes and their functions has undergone considerable change. No longer do we accept the old anatomic concept that the cell membrane is an inert lipid envelope surrounding the cell, serving merely to delimit the cell from its external environment. The membrane is now regarded as a dynamic structure organized to transport soluble, hydrophilic substances across its "lipid sea."¹ In cells with a specialized transport (absorption) function, such as those of the intestinal mucosa and proximal renal tubule, the membrane has been further differentiated into a mass of fingerlike projections, the microvilli, . . .