Surface Area and Volume Changes During Maturation of Reticulocytes in the Circulation of the Baboon

摘要

Changes in the surface area and volume of reticulocytes were measured during late stage maturation in vivo. Baboons were treated with erythropoietin to produce mild reticulocytosis. Reticulocyte-rich cohorts of cells were obtained from whole blood by density gradient centrifugation. The cohorts were labeled with biotin, reinfused into the animal, and recovered from whole blood samples by panning on avidin supports. Changes in the surface area, volume and membrane deformability were measured using micropipettes during the two to six weeks subsequent to reinfusion. For the entire cohort, membrane area decreased by 10-15% and cell volume decreased by approx. 8.5%, mostly within 24 hours after reinfusion. Estimates of the cellular dimensions of the reticulocyte subpopulation within this cohort indicate larger reductions in the mean cell area (12 to 30%) and mean cell volume (approx. 15%) of the reticulocytes themselves. Two weeks after reinfusion the distribution of cell size for the cohort was indistinguishable from whole blood. There was slight evidence of elevated membrane shear rigidity in some reticulocytes prior to reinfusion, but this slight increase disappeared within 24 hours after reinfusion. These are the first direct measurements of changes in the membrane physical properties of an identifiable cohort of reticulocytes as they mature in vivo.