Intracellular free calcium regulates the onset of the respiratory burst of human neutrophils activated by phorbol myristate acetate.
Thapsigargin was used to study the regulation of different static calcium level ([Ca2+]i) on the respiratory hurst of human neutrophils stimulated with phorbol myristate acetate (PMA). The result showed that the onset time of the respiratory hurst was obviously reduced by elevation of static [Ca2+]i but is still much longer than that stimulated with N-formylmethionylleucylphenylalanine (fMLP). To find the reason, the onset times of the respiratory burst stimulated with fMLP, 1,2-dioctanoyl-sn-glycerol (DiC8), and PMA were determined at different static [Ca2+]i. It turns out that although DiC8 was unable to induce the respiratory burst at low [Ca2+], the onset time of DiC8-stimulated response at high [Ca2+]i was almost the same as that stimulated with fMLP. The study revealed that the fast onset of the fMLP-stimulated respiratory burst in comparison with PMA-stimulated response is not only due to the transient rise of [Ca2+]i, but is also due to the higher efficiency of diacylglycerol (DAG) in activating protein kinase c (PKC). The determining step in governing the onset of a respiratory burst is the activation of PKC.
Hu
T H
TH
Institute of Biophysics, Chinese Academy of Sciences, Beijing, PR China.
Bei
L
L
Qian
Z M
ZM
Shen
X
X
D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004075:Diglycerides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism; D008934:Mitogens / Q000378:metabolism* / Q000494:pharmacology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D018375:Neutrophil Activation; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D016897:Respiratory Burst / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism* / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology
D004075:Diglycerides; D004791:Enzyme Inhibitors; D008934:Mitogens; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019284:Thapsigargin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium