title: Exposure of human neutrophils to exogenous nucleotides causes elevation in intracellular calcium, transmembrane calcium fluxes, and an alteration of a cytosolic factor resulting in enhanced superoxide production in response to FMLP and arachidonic acid.
abstract: Exposure of human neutrophils to micromolar concentrations of both hydrolyzable and nonhydrolyzable purine nucleotides caused the generation of transient rises in intracellular calcium (Ca2+), Ca2+ fluxes across the membrane, and primed the cells for enhanced production of superoxide (O2-) when subsequently exposed to agonists such as FMLP and arachidonic acid. The neutrophils were most sensitive to adenosine triphosphate (ATP) and ATP-gamma-S, which produced Ca2+ transients and enhanced O2- production at concentrations as low as 1 to 5 mumol/L, with a doubling of O2- generation at 25 to 50 mumol/L. Adenosine diphosphate (ADP), guanosine triphosphate (GTP), and 5'-adenylylimidodiphosphate (AMP-PNP) required approximately 10-fold higher concentrations to cause similar effects. Adenosine did not cause Ca2+ fluxes or a Ca2+ transient and was inhibitory of O2- production. There was a strong correlation between a nucleotide's ability to generate a Ca2+ response and its ability to enhance O2- generation. Nitrogen cavitation and subcellular fractionation of the neutrophils after a brief exposure to ATP, ATP-gamma-S, and AMP-PNP revealed that the enhanced O2- generating capacity was stable and detectable in a cell-free assay system. By combining variously treated cytosolic and membrane fractions, it was found that the enhanced O2- production was attributable to a modification of a component(s) of the cytosol.
authors.affiliation: Department of Pediatrics, University of Michigan, Ann Arbor 48109-0238.
authors.forename: R A
authors.initials: RA
authors.lastname: Axtell
authors.forename: R R
authors.initials: RR
authors.lastname: Sandborg
authors.forename: J E
authors.initials: JE
authors.lastname: Smolen
authors.forename: P A
authors.initials: PA
authors.lastname: Ward
authors.forename: L A
authors.initials: LA
authors.lastname: Boxer
mesh_terms: D000241:Adenosine / Q000378:metabolism; D001095:Arachidonic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism* / Q000493:pharmacokinetics; D002463:Cell Membrane Permeability; D003600:Cytosol / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D009711:Nucleotides / Q000494:pharmacology*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D001095:Arachidonic Acids; D009711:Nucleotides; D013481:Superoxides; D004533:Egtazic Acid; D009240:N-Formylmethionine Leucyl-Phenylalanine; D000241:Adenosine; D002118:Calcium