Relationship between the shape and the membrane potential of human red blood cells
- 1 February 1984
- journal article
- research article
- Published by Springer Nature in The Journal of Membrane Biology
- Vol. 82 (1), 1-13
- https://doi.org/10.1007/bf01870727
Abstract
Summary Microscopic observations of isotonic suspensions of human red blood cells demonstrate that cell shape is unaltered when the transmembrane electrical potential, orE m , is set in the range −85 to +10 mV with valinomycin at varied external K+, or K o .E m was measured with the fluorescent potentiometric indicator, diS-C3(5), as calibrated by a ΔpH method. Repeating Glaser's experiments in which echinocytosis was attributed to hyperpolarization, we found that at low ionic strength the pH-dependent effects of amphotericin B appear to be unrelated toE m . The effects of increased intracellular Ca2+, or Ca o , on echinocytosis and onE m are separable. With Ca ionophore A23187 half-maximal echinocytosis occurs at greater Ca o than that which induces the half-maximal hyperpolarization associated with Ca-induced K+ conductance (Gardos effect). Thus, cells hyperpolarized by increased Ca o remain discoidal when Ca is below the threshold for echinocytosis. With A23187 and higher Ca o , extensive echinocytosis occurs in cells which are either hyperpolarized or at their resting potential. The Ca-activation curve for echinocytosis is left-shifted by low K o , a new observation consistent with increased DIDS-sensitive uptake of45Ca by hyperpolarized cells. These results support the following conclusions: (1) the shape and membrane potential of human red blood cells are independent under the conditions studied; (2) in cells treated with A23187, the Gardos effect facilitates echinocytosis by increasing Ca.Keywords
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