(Received for publication, March 19, 1959) The present work is concerned with an analysis of some factors which determine the distribution of glucose between isolated lymph node cells and extracellular medium. Such information is relevant to the increasing interest in the role of permeability in the regulation of cell metabolism. Studies of permeability of isolated mammalian cells have utilized erythrocytes almost exclusively (2). More recently, ascites tumor cells have been used for this purpose (3, 4). In respect to correlations between distribution and utilization of glucose, skeletal muscle has been shown to be a suitable tissue (5). For correlating permeability and metabolism, one wishes ideally to measure simultaneously the rate of penetration and the rates of metabolic conversion of a penetrant. For this purpose, isolated cells should offer advantages over more complex tissue prepara- tions, such as skeletal muscle. In the present study, isolated lymph node cells were used. These cells, which are readily obtainable as single cell suspen- sions, are active in the formation of antibodies and y-globulins and are more representative of mammalian cells, in general, than are erythrocytes or ascites tumor cells. Lymph node cells were found to be well suited for determination of the rate of glucose utilization, since they exhibit high glycolytic activities and con- tain, in contrast to muscle, only trace amounts of glycogen. Complications arising from glycogenolysis (5) could, therefore, he excluded. Unfortunately, however, penetration of glucose into lymph node cells was too fast, even at O”, for determination of rate constants for entry. In view of this limitation, intracel- lular sugar concentrations were evaluated in the steady state, i.e. when intracellular sugar concentrations were constant with time. Utilization of glucose or other rapidly metabolized sugars was measured concomitantly with distribution. Information concerning interrelationships between permeability and utiliza- tion was obtained by deliberately altering one or both of these processes. * A preliminary report was given at the 42nd Annual Meeting of the American Society of Biological Chemists in Chicago (1) and at the IV. International Congress of Biochemistry, Vienna,