Evidence against a Single Renal Transport Defect in Cystinuria

Transport of Neutral and Dibasic Amino Acids by Human Leukocytes: Absence of Defect in Cystinuria*

“…Recent in vitro studies have demonstrated defective transport of lysine and arginine by human gut and kidney in cystinuria (7)(8)(9). Cystine uptake was also defective in intestinal mucosa (8,9) but, surprisingly, not in kidney cortex from cystinuric subjects (7).…”

“…Cystine uptake was also defective in intestinal mucosa (8,9) but, surprisingly, not in kidney cortex from cystinuric subjects (7). To characterize the transport systems for the dibasic amino acids and cystine in a third human tissue and to determine if defects in amino acid transport exist in tissues other than gut and kidney, the present studies with isolated peripheral leukocytes were undertaken.…”

Delineation of Cystine and Cysteine Transport Systems in Rat Kidney Cortex by Developmental Patterns

“…[3][4][5][6] In this regard, an outstanding question has been whether there are separate transport mechanisms for cystine and cysteine in renal tubule cells. We have previously attempted to delineate differences in transport parameters for these two amino acids in adult rat kidney cortex slices, and although the results of these studies were indicative of separate systems, they were not conclusive.…”

A new transport interaction of dibasic amino acids and citrulline in human kidney.

“…Dent and Rose (1951) first postulated that reabsorption of these four amino acids in the renal tubule cell is defective in cystinuric patients. Recent studies (Rosenberg et al 1962;Fox et al 1964;Segal et al 1977) using both rat and human kidney cortex slices revealed that dibasic amino acids shared a common transport system, but that cystine uptake was controlled by an independent mechanism.Several clinical observations, of hyperdibasicaminoaciduria without cystinuria (Oyanagi et al 1970;Whelan and Scriver 1968) and cystinuria without hyperdibasicaminoaciduria (Brodehl et al 1967), support separate membrane transport systems for cystine and dibasic amino acids. The purpose of the present study is to describe the transport interaction of dibasic amino acids and citrulline which was hitherto unrecognized in the human kidney.…”

“…Dent and Rose (1951) first postulated that reabsorption of these four amino acids in the renal tubule cell is defective in cystinuric patients. Recent studies (Rosenberg et al 1962;Fox et al 1964;Segal et al 1977) using both rat and human kidney cortex slices revealed that dibasic amino acids shared a common transport system, but that cystine uptake was controlled by an independent mechanism.…”