McMENAMY and associates1 point out that understanding of the role of the blood in amino acid transport and metabolism requires information not only about the plasma concentrations and turnover of these substances, but also about their distribution between the plasma and the formed elements of the blood. While concentrations of unbound amino acids and their contents in plasma, in erythrocytes, and in leukocytes have been reported by many workers, simultaneous measurements of unbound amino acids in the blood compartments received little attention. McMenamy and associates report from the Department of Biological Chemistry and the Department of Surgery, Harvard Medical School, Fifth Surgical [Harvard] Service of the Boston City Hospital, on methods used for the measurement of concurrent concentrations of unbound amino acid in plasma, erythrocytes, leukocytes, and urine from the study of normal fasting subjects.
Fifty to sixty ml. of blood was collected from each subject on a fasting