title: UVA-induced calcium oscillations in rat mast cells.
abstract: UVA is a major bio-active component in solar irradiation, and is shown to have immunomodulatory and anti-inflammatory effects. The detailed molecular mechanism of UVA action in regard to calcium signaling in mast cells, however, is not fully understood. In this study, it was found that UVA induced ROS formation and cytosolic calcium oscillations in individual rat mast cells. Exogenously added H2O2 and hypoxanthine/xanthine oxidase (HX/XOD) mimicked UVA effects on cytosolic calcium increases. Regular calcium oscillation induced by UVA irradiation was inhibited completely by the phosphatidylinositol-specific phospholipase C inhibitor U73122, but U73343 was without effect. Tetrandrine, a calcium entry blocker, or calcium-free buffer abolished UVA-induced calcium oscillations. L-type calcium channel blocker nifedipine and stores-operated calcium channel blocker SK&F96365 had no such inhibitory effect. ROS induction by UVA was abolished after pre-incubation with anti-oxidant NAC or with NAD(P)H oxidase inhibitor DPI; such treatment also made UVA-induced calcium oscillation to disappear. UVA irradiation did not increase mast cell diameter, but it made mast cell structure more granular. Spectral confocal imaging revealed that the emission spectrum of the endogenous fluorophore in single mast cell contained a sizable peak which corresponded to that of NAD(P)H. Taken together, these data suggest that UVA in rat mast cells could activate NAD(P)H oxidase, to produce ROS, which in turn activates phospholipase C signaling, to trigger regular cytosolic calcium oscillation.
authors.affiliation: Institute of Cell Biology, Beijing Normal University, Beijing 100875, China.
authors.forename: Yan Dong
authors.initials: YD
authors.lastname: Zhou
authors.forename: Xiao Feng
authors.initials: XF
authors.lastname: Fang
authors.forename: Zong Jie
authors.initials: ZJ
authors.lastname: Cui
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000528:radiation effects*; D002395:Catecholamines / Q000494:pharmacology; D004789:Enzyme Activation / Q000528:radiation effects; D004963:Estrenes / Q000494:pharmacology; D016257:Fura-2; D048288:Imidazolines / Q000494:pharmacology; D008407:Mast Cells / Q000378:metabolism* / Q000528:radiation effects; D018613:Microscopy, Confocal; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D002121:Calcium Channel Blockers; D002395:Catecholamines; D004963:Estrenes; D048288:Imidazolines; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C074854:U 73343; C011775:(3,4-dihydroxyphenylamino)-2-imidazoline; D019255:NADPH Oxidases; D016257:Fura-2