Divalent cation effects on membrane bending in heated erythrocytes

Abstract

ABSTRACT:The thermal fragmentation of human erythroeytes involves either surface wave growth and membrane externalization at the cell rim or membrane internalization at the cell dimple.In symmetrical monovalent electrolytes an increase in membrane internalization at the cell dimple correlates with the decrease in zeta potential arising from surface charge (sialic acid residue) depletion.The influence of divalent cations on thermal fragmentation is examined in this work.The erythrocyte zeta potential decreased when divalent cations replaced some Na + in the cell-suspending phase.The incidence of membrane internalization increased in rank order Ca 2+ > Ba 2+ > Mg ~+ ~ Sr 2+. Calcium continued to influence the thermal fragmentation of cells highly depleted of sialic acid, suggesting that the ion also interacted with membrane sites other than sialic acid.The divalent cation influence on cell fragmentation was shown to be greater than that due to zeta potential decrease alone.This conclusion was supported by the observation that the divalent cation-induced changes in zeta potential showed much less cation specificity than did the changes induced in the thermal fragmentation pattern. The result implies that the specificity of the divalent cation effects was due to interactions within the erythrocyte shear layer.The possibility that the interaction is with membrane lipids is examined.

Can morphological changes of erythrocytes be driven by hemoglobin?

“…slower than 0.75 C per second) and that morphological changes proceed via two major scenarios. Either the biconcave erythrocyte form changes to a rosette shape with well-established protuberances, or the erythrocyte fragments into several parts [8]. Nearly 50 % of erythrocytes did not undergo any visible morphological change at 49 • -50 • C [8].…”

“…This trapping was prescribed both to changing the form of erythrocyte (from disc to sphere) [13] and to plasticity loss [14]. Morphological changes at 49 • -50 • C were studied by scanning electron micrography in [8]. It was found that thermal effects at 49 • -50 • C depends rather weakly on heating rate (provided that this rate is sufficiently slow, i.e.…”

“…Either the biconcave erythrocyte form changes to a rosette shape with well-established protuberances, or the erythrocyte fragments into several parts [8]. Nearly 50 % of erythrocytes did not undergo any visible morphological change at 49 • -50 • C [8]. The effect of morphological changes was prescribed to denaturation of spectrin, a cytoskeletal protein that stitches the intracellular side of the plasma membrane in eukaryotic cells including erythrocyte [9,10,12].…”