Cytodifferentiation and Membrane Transport Properties in LK Sheep Red Cells

Abstract

Young cells produced in LK sheep during rapid hematopoiesis after massive hemorrhage contain more K than the cells which are normally released into the circulation. The K content in these new cells falls to that characteristic of mature LK cells after a few days in the circulation. K transport properties in young and old cells before and after massive bleeding were studied. Young and old cells were separated by means of a density gradient centrifugation technique. Evidence showing that younger cells are found in the lower density fractions is presented. Active transport of K in the lightest fraction as measured by strophanthidin-sensitive influx was four to five times greater in red cells drawn 6 days after massive bleeding while the K leak as measured by strophanthidin-insensitive influx was only slightly larger. No change after bleeding was observed in older cells which had been present in the circulation prior to the hemorrhage. It is concluded that the high K content of young cells produced in LK sheep after bleeding is due to temporary retention of membrane K transport properties characteristic of HK cells. Thus, genetically determined modification of membrane transport properties has been shown to occur in nondividing circulating red cells.

LK sheep reticulocytosis: effect of anti-L on K influx and in vitro maturation.

“…Fig. 6, Lee et al, 1966). Aside from the general notion that sheep reticulocytes are larger than mature erythrocytes (Ellory et al, 1970), our findings are supported by the electric sizing studies of , which revealed that bleeding of sheep induced a macrocytic erythrocyte population between 5 and 12 d after hemorrhage.…”

“…In agreement with well-established findings (Lee et al, 1966;Blostein et al, 40- 1974; Dunham and Blostein, 1976), the reticulocytes of LK sheep were found to have a high cellular K + concentration [K § as shown in Fig. 3, in which K + and Na + compositions measured on the same aliquots of cells illustrated in Fig.…”

“…It should be noted that the day of harvesting the top 10% cells most active in K + pump transport is very critical, and "peak performance" of these cells may well be missed if one bleeds one day too early or too late. It is possible that the lightest fraction of cells in the earlier work (Lee, et al, 1966) did not contain as many reticulocytes as we observed (near 100%) and hence was more mature.…”

“…The finding that the immature cells have high K + content and K § pump activity was first described by Lee et al (1966). However, we determined that the K + pump activity in the immature cells is 6-7 times greater than that reported by them.…”

Study of maturation of membrane transport function in red blood cells by X-ray microanalysis

“…Our previous study of the dog bone marrow (Kirk, Lee & Tosteson, 1978) indicated that the modification of membrane transport function from high potassium type to low potassium type probably occurs early in the maturation sequence, before hemoglobin synthesis is complete. The finding of HK stress reticulocytes in anemic dogs (Henriques & Orskov, 1936; also see Parker, 1972) and in LK sheep after severe bleeding (Blunt & Evans, 1965 ;Lee, Woo & Tosteson, 1966) suggests that the modification of membrane transport may occur as late as the reticulocyte stage. This paper examines the time course of the maturation of membrane transport function in dog red cells during normal erythropoiesis and during accelerated erythropoiesis.…”