title: Thrombin releases calcium from internal stores of ultraviolet C-treated V79 fibroblasts independent of phosphatidylinositol bisphosphate hydrolysis: role of oxidative stress.
abstract: V79 fibroblasts were treated with ultraviolet (UV) C radiation alone as well as in conjunction with chronic oxidative stress. The effects of these treatments on calcium signaling were observed at 30 min post-irradiation. In the absence of extracellular calcium, thrombin released calcium from internal stores of UVC-irradiated V79 fibroblasts even after exposure to neomycin. In neomycin-treated control and chronic oxidative stress cells, no calcium release by thrombin was observed after chelation of external calcium. Calcium release by thrombin from internal stores of UV-irradiated and neomycin-treated cells was completely abolished by pretreatment with N-acetyl cysteine and dexamethasone. Cellular total soluble thiol content which is a good indicator of cellular reduced glutathione (GSH) level was significantly elevated 30 min after ultraviolet radiation, indicating an adaptive response after oxidative stress. Chronic oxidative stress alone resulted in a much smaller increase in GSH but chronic oxidative stress in conjunction with UVC produced a very prominent elevation in GSH levels. Our data suggest that thrombin can cause calcium release from internal stores of ultraviolet-irradiated fibroblasts which is independent of phosphatidylinositol bisphosphate hydrolysis and is directly related to the level of oxidative stress. Involvement of phospholipase A2 and a role for its products as possible mediators of calcium release from intracellular stores, is strongly indicated.
authors.affiliation: Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, Calcutta, India.
authors.forename: S
authors.initials: S
authors.lastname: Bagchi
authors.forename: G
authors.initials: G
authors.lastname: Bhaumik
authors.forename: S
authors.initials: S
authors.lastname: Raha
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002478:Cells, Cultured; D006224:Cricetinae; D003412:Cricetulus; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects; D019833:Genistein / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3; D006868:Hydrolysis; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000378:metabolism; D018384:Oxidative Stress; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D016861:Cyclooxygenase Inhibitors; D016859:Lipoxygenase Inhibitors; D019269:Phosphatidylinositol 4,5-Diphosphate; D013438:Sulfhydryl Compounds; D019833:Genistein; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3; D013917:Thrombin; D002118:Calcium