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Near‐visible ultraviolet light induces a novel ubiquitous calcium‐permeable cation current in mammalian cell lines
Author(s) -
Mendez Francisco,
Penner Reinhold
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.365bt.x
Subject(s) - chemistry , biophysics , photochemistry , membrane , radical , patch clamp , calcium , glutathione , hydrogen peroxide , ascorbic acid , lipid peroxidation , ion channel , biochemistry , antioxidant , enzyme , biology , receptor , food science , organic chemistry
1 We studied the immediate and short‐term effects of UV light in the near‐visible range at the cellular and membrane level using the whole‐cell patch‐clamp technique in combination with digital fluorescence imaging. 2 Illumination with monochromatic UVA light (340‐380 nm) induced a sustained non‐saturable increase in membrane conductance dependent on wavelength and light intensity in several different mammalian cell types including RBL, mast, HEK, PC12 and 3T3 cells. 3 The current was non‐selective for cations and permeable to Ca 2+ , but was inhibited by trivalent cations and was not due to the activation of an endogenous ion channel. We termed this novel current I LiNC for light‐induced non‐selective cation current. 4 A similar current was evoked by chemical peroxidants such as hydrogen peroxide and tert‐butylhydroperoxide, but not by cytosolic oxidized glutathione. 5 The free‐radical scavengers tocopherol (vitamin E) and ascorbic acid (vitamin C) significantly reduced the UV light effect. 6 The generation of the current was membrane delimited since it could be induced by the same UVA treatment in cell‐free membrane patches showing a similar wavelength dependence. 7 These results suggest that I LiNC is activated by UVA light‐induced generation of free radicals acting through lipid or protein peroxidation, and may represent a ubiquitous mechanism by which Na + and Ca 2+ can enter cells after phototoxic or free radical‐induced membrane damage.