The correlation of composition and morphology during the high to low potassium transition in single erythropoietic cells

Abstract

The change from high potassium dog erythroid cells to low potassium red blood cells during erythropoiesis was investigated by X-ray microanalysis of single cells. A correlation of morphology and composition, using freeze-dried cryosectioned preparations, showed that during normal erythropoiesis in dog bone marrow the switch from high potassium to low potassium occurs during the change from early to late nucleated erythroid cells, and in synchrony with the beginning of iron accumulation. In contrast, during rapid erythropoiesis in dogs with phenylhydrazine-induced anemia, the most prominent change in cation composition as well as the accumulation of iron occurs during the reticulocyte stage in the peripheral blood. The determination of the absolute amounts of sodium and potassium per cell in stress reticulocytes of peripheral blood indicated that the changeover from high potassium to low potassium actually occurs by the loss of cellular potassium during volume reduction, with little change in the amount of cellular sodium. This suggests that maturation may involve a selective change in potassium permeability. Lastly, it was observed that not all cells followed the predominant pathway with respect to change in morphology, membrane permeability and hemoglobin synthesis. One particular subpopulation appeared to follow a sequence which expressed the complete HK to LK transition before the accumulation of any iron; this implies the possibility of completing protein synthesis in a low potassium intracellular milieu.

Surfaces of cryosections: is cryosectioning ‘cutting’ or ‘fracturing’?

“…It is reassuring to note that with a sharp knife and small knife advancements, smooth sections can be obtained and major redistribution of elements across biological membranes does not occur as a result of cutting. This has been demonstrated in X-ray microanalysis studies by the fact that the expected normal high potassium concentrations in the analysed cytosols and the expected low levels outside of the cells have been obtained by many laboratories (Gupta et al, 1976;Somlyo et al, 1977;Dorge et al, 1978;Rick et al, 1978;Andrews et al, 1983;Kirk et al, 1983).…”

Hereditary Phosphofructokinase Deficiency in Wachtelhunds

“…Mature canine erythrocytes (except for some Asian breeds) have potassium concentrations similar to serum, whereas reticulocytes have a higher potassium content. 18 Intravascular hemolysis is unlikely to cause life-threatening hyperkalemia in PFK-deficient dogs because PFK-deficient reticulocytes are not alkaline fragile as they have DPG concentrations similar to that of normal canine erythrocytes. 12 Thus, mainly mature erythrocytes not containing high intracellular potassium would be lysed.…”

Anion transport during maturation of erythroblastic cells

“…X-ray microanalysis yields single-cell data on the elemental composition of morphologically identifiable ceils at different stages of maturation, thereby permitting the interpretation of data in terms of net transport of elements in and out of cells. This technique has allowed us to study the transitory changes of potassium and rubidium concentrations in erythropoietic cells (Kirk, Andrews & Lee, 1983. Since chloride is present in large amounts in the mature erythrocytes and their precursors (erythroblastic cells), we have used another monovalent anion, bromide, which is not present in the cells to study the anion transport system in maturing erythroblastic ceils.…”