fMLP-induced respiratory burst and the intracellular Ca2+ signal are not interrelated in neutrophils.
Reactive oxygen intermediate (ROI) production and the development of the intracellular (IC) Ca2+ ([Ca2+]i) signal by formyl-Met-Leu-Phe (fMLP) stimuli were investigated in neutrophils. When the concentration was varied between 2.3 nM-2.3 microM, ROI production and the [Ca2+]i signal showed different fMLP concentration dependencies. ROI production increased continuously with increasing fMLP concentrations, while the [Ca2+]i signal responses reached a plateau around 230 nM fMLP. Moreover, when a consecutive, 2.3 microM fMLP stimulus was applied 10 min after the first fMLP stimulus, the intensity of the ROI production and that of the [Ca2+]i signal showed a variable dependence on the fMLP concentration of the first stimulus. An initial fMLP dose of 2.3 nM and 23 nM sensitized the cells regarding their ROI production and [Ca2+]i signals. After a first fMLP stimulus of 230 nM, the second stimulus produced an increased [Ca2+]i signal, while no ROI production could be activated. A strong fMLP stimulus of 2.3 microM desensitized the cells regarding both [Ca2+]i signal and ROI production. However, even in these desensitized cells, a high level of ROI production could be evoked by other stimuli like PMA or opsonized zymosan. The differences observed between the fMLP concentration dependence of ROI production and the [Ca2+]i signal strongly suggest that these two phenomena are not interrelated.
Németh
K
K
Department of Pathophysiology, Institute of Health Protection, Hungarian Defense Forces, Budapest.
Furész
J
J
Adorjáni
E
E
Cseko
C
C
Bielik
H
H
Lakatos
S
S
D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D003571:Cytochalasin B / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects* / Q000502:physiology
D017382:Reactive Oxygen Species; D003571:Cytochalasin B; D009240:N-Formylmethionine Leucyl-Phenylalanine; D019255:NADPH Oxidases