title: GTP gamma S-induced calcium transients and exocytosis in human neutrophils.
abstract: Exocytosis and intracellular free calcium ([Ca2+]in) were simultaneously recorded in single human neutrophils using patch-clamp capacitance measurements and the fura-2 fluorescence ratio method. Intracellular application of guanosine-5'-O(3-thiotriphosphate) (GTP gamma S) stimulates both exocytosis and a calcium transient. The calcium transient starts to develop after a lag phase of approximately 40 s and normally appears to trigger the onset of exocytosis indicated by the beginning of the capacitance increase. After this delay [Ca2+]in increases from approximately 150 nM to approximately 600 nM with a sigmoidal time course. The peak concentration is reached within approximately 30 s but the main increase occurs during approximately 3 s. [Ca2+]in subsequently decays within 1-2 min to a level which is close to the resting value. This calcium transient is due to calcium release from inositoltrisphosphate-sensitive intracellular stores. Exocytosis also occurs if the calcium transient is abolished by intracellular EGTA but the lag phase is markedly prolonged. The GTP gamma S-induced calcium transient is very similar to that observed after stimulation with N-formyl-methionyl-leucyl-phenylalanine. The interplay between guanine nucleotides, [Ca2+]in and exocytosis in neutrophils closely resembles previous results obtained in mast cells suggesting a similar regulation of exocytosis in both cell types.
authors.affiliation: Biophysics Group, Freie Universität Berlin, FRG.
authors.forename: O
authors.initials: O
authors.lastname: Nüsse
authors.forename: M
authors.initials: M
authors.lastname: Lindau
mesh_terms: D002118:Calcium / Q000097:blood*; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D006160:Guanosine Triphosphate; D002118:Calcium