AJP - Cell Physiology, Vol 257, Issue 5 C859-C864, Copyright © 1989 by American Physiological Society
Suppressive action of cobalt on exocytosis and respiratory burst in neutrophils
J. G. Elferink and M. Deierkauf
Department of Medical Biochemistry, Sylvius Laboratories, University of Leiden, The Netherlands.
Activation of exocytosis and respiratory burst in rabbit neutrophils by the
chemotactic peptide fMet-Leu-Phe is inhibited by Co2+. Inhibition is
antagonized by extracellular Ca2+ and is dependent on the time of
preincubation of cells with Co2+ before addition of activator. Co2+
inhibits the enhancement of 45Ca association that occurs during activation
with fMet-Leu-Phe. Interference with Ca2+ translocation across the plasma
membrane by Co2+ is probably not the cause of inhibition of neutrophil
activation, because activation in the absence of extracellular Ca2+ is
inhibited by Co2+. Activation of neutrophils by phorbol myristate acetate
is inhibited at higher Co2+ concentrations than activation by fMet-Leu-Phe.
Inhibition of the superoxide production by Co2+ occurs both in the presence
or in the absence of cytochalasin B. Fluorescence of neutrophils loaded
with quin2 is diminished by Co2+, indicating that Co2+ had entered into the
cytoplasm. The results are compatible with the view that Co2+ inhibits
exocytosis and respiratory burst in neutrophils by an interaction with a
Ca2+-dependent intracellular target.
