Is cytosolic ionized calcium regulating neutrophil activation?
The concentration of cytosolic ionized calcium, [Ca2+]i, was measured in intact neutrophils by use of a fluorescent indicator trapped in the icytoplasm. A given rise of [Ca2+]i elicited by the chemotactic peptide formylmethionylleucylphenylalanine (FMLP) was associated with a much greater degree of superoxide generation and myeloperoxidase secretion than was the same or larger [Ca2+]i produced by a specific calcium ionophore, ionomycin, which bypasses cell surface receptors. Thus, FMLP appears to generate some important excitatory signal in addition to a rise in [Ca2+]i and exocytosis and superoxide generation in neutrophils may not be simply dependent on [Ca2+]i as is widely supposed.
D002118:Calcium / Q000502:physiology*; D003593:Cytoplasm / Q000502:physiology; D004987:Ethers / Q000494:pharmacology; D005089:Exocytosis; D006801:Humans; D015759:Ionomycin; D007476:Ionophores / Q000494:pharmacology; D008247:Lysosomes / Q000201:enzymology; D009239:N-Formylmethionine / Q000031:analogs & derivatives / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine; D009504:Neutrophils / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
D004987:Ethers; D007476:Ionophores; D009842:Oligopeptides; D013481:Superoxides; D009239:N-Formylmethionine; D015759:Ionomycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; D010100:Oxygen; D002118:Calcium