INFLUENCE OF IONOPHORE A23187 ON PLASTIC BEHAVIOR OF NORMAL ERYTHROCYTES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 88  (1) , 81-94
Abstract
Previous studies have demonstrated that A23187 [2(3.beta.,9.alpha.,11.beta.-trimethyl)-8-(2-pyrrolecarboxymethyl)-1,7-dioxaspiro [6,6] undecyl-2.beta.-methyl-5-methylaminobenzoxazole-4-carboxylic acid], an ionophore which selectively transports divalent cations across cell membranes, has profound effects on human erythrocytes; it causes red cells to take up Ca; lose K, water and ATP; convert from biconcave discs to echinocytes and spheroechinocytes; and become more rigid. The influence of Ca uptake induced by the ionophore on the behavior of individual erythrocyte membranes by the micropipette aspiration technique was examined. Exposure of erythrocytes to Ca and A23187 for intervals of up to 30 min resulted in marked changes in membrane viscoelastic properties, including the development of increased resistance to aspiration. The most striking manifestation of altered membrane mechanics was apparent after 10 min of incubation. Cells pulled into the pipette for a few seconds and then extruded back into the medium retained the deformity imposed by the pipette for several seconds to a few minutes before regaining the form they manifested prior to initial aspiration. The Ca-induced changes in erythrocyte behavior strongly support the concept that extrinsic proteins located inside the membrane provide mechanical support to the cell wall, and that increased levels of Ca cause precipitation or cross-linking of the proteins that responsible for the increased resistance to deformation and recoil observed after aspiration into micropipettes.