Acute cell volume changes in anisotonic media affect F-actin content of HL-60 cells.
To investigate the possible role of the cytoskeleton in volume regulatory responses of human promyelocytic leukemic (HL-60) cells, we monitored and modulated the F-actin content of these cells undergoing volume regulation in anisotonic media. Initial volume changes of HL-60 cells suspended in hypertonic media followed a Van't Hoff relationship, and intracellular F-actin content during volume regulatory responses in anisotonic media changed concomitantly as an inverse function of the volume shifts. These F-actin changes were shown to be an explicit function of cell volume and not tonicity of the medium. The data fit with the idea that changes in affinity of actin-binding proteins (ABPs) for actin and/or changes in the overall effective critical concentration of actin occur during acute cell volume changes, producing shifts in the relative amounts of G- and F-actin. Treatment of HL-60 cells with dihydrocytochalasin B (DHB), which perturbs cellular actin assembly, lowered resting levels of intracellular F-actin but did not prevent volume-associated F-actin changes in anisotonic media. Despite the lowered F-actin levels, HL-60 cells in the presence of DHB still undergo normal volume regulatory responses. Thus the absolute amount of intracellular F-actin does not appear to be critical for volume regulation in HL-60 cells.
Hallows
K R
KR
Department of Biophysics, University of Rochester Medical Center, New York 14642.
Packman
C H
CH
Knauf
P A
PA
D000199:Actins / Q000378:metabolism*; D003572:Cytochalasins / Q000494:pharmacology; D003599:Cytoskeleton / Q000502:physiology*; D004581:Electronics; D006801:Humans; D006982:Hypertonic Solutions / Q000494:pharmacology; D007700:Kinetics; D009994:Osmolar Concentration; D014407:Tumor Cells, Cultured
D000199:Actins; D003572:Cytochalasins; D006982:Hypertonic Solutions