AJP - Cell Physiology, Vol 237, Issue 1 43-C49, Copyright © 1979 by American Physiological Society
Effect of chemotactic factors on calcium levels of rabbit neutrophils
R. J. Petroski, P. H. Naccache, E. L. Becker and R. I. Sha'afi
Studies were undertaken to provide a systematic investigation of the effect
of the chemotactic factor, formyl-methionyl-leucyl-phenylalanine
(F-Met-Leu-Phe), on the levels of total and exchangeable calcium in rabbit
neutrophils. The 45Ca2+ specific activity of the cells was thus determined
before and after stimulation by chemotactic factors. Total cell calcium was
found to be constant in neutrophils equilibrated with 50-1,000 microM
extracellular calcium but decreased by 30% at an extracellular calcium
concentration of 5 microM. F-Met-Leu-Phe had little, if any, statistically
significant effect on the level of total cell calcium. In contrast,
F-Met-Leu-Phe affects greatly the steady-state levels of radioactive
calcium in the neutrophils. The primary effect is an initial loss followed
by an increase of cell-associated radiolabeled calcium. The extent and even
the direction of the effect depends on the level of extracellular calcium
as well as the concentration of the chemotactic factor and the duration of
its interaction with the cell. The results are discussed in terms of the
hypothesis that the binding of the chemotactic factor to its receptor leads
to, among other things, a graded displacement of previously bound Ca2+.
