AJP - Cell Physiology, Vol 252, Issue 3 C300-C306, Copyright © 1987 by American Physiological Society
Cell volume regulation in hemoglobin CC and AA erythrocytes
L. R. Berkowitz and E. P. Orringer
Swelling hemoglobin CC erythrocytes stimulates a ouabain-insensitive K flux
that restores original cell volume. This volume regulatory pathway was
characterized for its anion dependence, sensitivity to loop diuretics, and
requirement for Na. The swelling-induced K flux was eliminated if
intracellular chloride was replaced by nitrate and both swelling-activated
K influx and efflux were partially inhibited by 1 mM furosemide or
bumetanide. K influx in swollen hemoglobin CC cells was not diminished when
Na in the incubation medium was replaced with choline, indicating Na
independence of the swelling-induced flux. Identical experiments with
hemoglobin AA cells also demonstrated a swelling-induced increase in K
flux, but the magnitude and duration of this increase were considerably
less than that seen with hemoglobin CC cells. The increased K flux in
hemoglobin AA cells was likewise sensitive to anion replacement and to loop
diuretics and did not require the presence of Na. These data indicate that
a volume-activated K pathway with similar transport characteristics exists
in both hemoglobin CC and AA red cells.
