Changes in K+ pump transport and ouabain binding sites in erythrocytes of genetically low K+ lambs

The transition from HK to LK phenotype in the red cells of newborn genetically LK lambs.

“…The number of sites per cell at 100% adult Hb in Fig. 6 was higher than values obtained in a recent study on adult sheep erythrocytes (Lauf et al, 1978). There is considerable variation in reported values for number of ouabain binding sites on LK sheep red cells (cf.…”

“…OUABAIN BINDING Tritiated ouabain binding studies have been used to determine the number of Na'/K' pump sites on lamb and adult sheep red cells (Dunham and Hoffman, 1971 ;Lauf et al ., 1978) . In the present study we therefore measured ouabain binding to determine changes in the number of Na+/K+ pumps per cell during development ; the data are presented in data was significantly different from zero (P = 0.01) .…”

“…It has been known for a number of years that the genetic polymorphism involving red cell potassium concentrations in sheep (HK and LK phenotypes) is not manifest in newborn lambs, but becomes detectable during the first 2 months of life (Evans and Blunt, 1961 ;Blechner, 1961 ; Drury and Tucker, 1963 ; Ellory and Tucker, 1969a) . At birth the red cells of all sheep have high concentrations of potassium, and it is only when the blood group antigen L first makes its appearance on the cells that genetically LK lambs progressively assume the LK phenotype characterized not only by an alteration of Na' and K+ concentrations, but also by a decline in active K+ transport and the number of Na'/K+ pumps per cell (Dunham and Hoffman, 1971 ;Lauf et al, 1978) . This observation provided the basis for the hypothesis that the L antigen acts by inhibiting active potassium transport in adult type LK red cells (Tucker, 1968) .…”

Na+ K+ pump and passive K+ transport in large and small red cell populations of anemic high and low K+ sheep

“…The process by which the mature LK red cell develops in the hematopoietic system, i.e., the HWLK transition, is still unclear. To address this problem, two experimental approaches have been used: first, the age-dependent replacement of fetal HK with adult LK cells in lambs (Evans and Blunt, 1961;Drury and Tucker, 1963;Dunham and Hoffman, 1971;Lauf et al, 1978;Valet et al, 1978; Lauf and Valet, 1980; Tucker et al, 1982), and second the study of membrane transport changes during maturation of reticulocytes to the final LK steady state cells in adult sheep (Lee et al, 1966;Dunham and Blostein, 1976;Kim et al, 1980; Blostein et al, 1981; Tucker and Young, 1981). In the present study, we followed the membrane transport events accompanying the in vivo maturation of stress-induced reticulocytes into both anucleate HK and LK red cells.Our basic strategy was first to isolate by centrifugal elutriation and second to characterize by flow cytophotometry (Valet et al, 1978; Lauf and Valet, 1980) the reticulocyte populations newly produced in response to massive bleeding of both adult LK and HK sheep.…”