Treatment of the macrophage-like P388D.1 cells with bacterial lipopolysaccharide and interferon-gamma causes long-term alterations in calcium metabolism.
The intracellular calcium concentrations ([Ca2+]i) of P338D.1 macrophage-like cells, activated with interferon-gamma (IFN-gamma) and/or bacterial lipopolysaccharide (LPS) were determined using fura-2/AM and ratiometric imaging techniques. Treatment of macrophages with IFN-gamma and LPS resulted in significant downward shift in [Ca2+]i, 8, 16 and 24 h but not at 1 and 4 h after treatment. The decrease in [Ca2+]i also occurred when macrophages were treated with LPS only, but not after exposure of the cells to recombinant IFN-gamma, indicating that LPS was an essential signal in the observed changes in [Ca2+]i of activated macrophages. The IFN-gamma and/or LPS alteration in the [Ca2+]i, paralleled the in vitro nitric oxide production of the activated macrophages, 8, 16 and 24 h after treatment. The decrease in the [Ca2+]i may be caused by vigorous buffering and storing of Ca2+ by macrophages to below the normal resting quantities, following the reported transient increase in Ca2+ during the priming stage of macrophage activation. Thus, the downward shift in [Ca2+]I may play a physiological role in the activation processes of macrophages for antimicrobial responses.
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
M A
MA
Lowry
J I
JI
Goldberg
M
M
Belosevic
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D007371:Interferon-gamma / Q000378:metabolism / Q000494:pharmacology; D007941:Leukemia P388 / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis; D012486:Salmonella typhimurium; D013997:Time Factors; D014407:Tumor Cells, Cultured
D008070:Lipopolysaccharides; D009569:Nitric Oxide; D007371:Interferon-gamma; D002118:Calcium