title: Norepinephrine-induced apoptotic and hypertrophic responses in H9c2 cardiac myoblasts are characterized by different repertoire of reactive oxygen species generation.
abstract: Despite recent advances, the role of ROS in mediating hypertrophic and apoptotic responses in cardiac myocytes elicited by norepinephrine (NE) is rather poorly understood. We demonstrate through our experiments that H9c2 cardiac myoblasts treated with 2 µM NE (hypertrophic dose) generate DCFH-DA positive ROS only for 2h; while those treated with 100 µM NE (apoptotic dose) sustains generation for 48 h, followed by apoptosis. Though the levels of DCFH fluorescence were comparable at early time points in the two treatment sets, its quenching by DPI, catalase and MnTmPyP suggested the existence of a different repertoire of ROS. Both doses of NE also induced moderate levels of H2O2 but with different kinetics. Sustained but intermittent generation of highly reactive species detectable by HPF was seen in both treatment sets but no peroxynitrite was generated in either conditions. Sustained generation of hydroxyl radicals with no appreciable differences were noticed in both treatment sets. Nevertheless, despite similar profile of ROS generation between the two conditions, extensive DNA damage as evident from the increase in 8-OH-dG content, formation of γ-H2AX and PARP cleavage was seen only in cells treated with the higher dose of NE. We therefore conclude that hypertrophic and apoptotic doses of NE generate distinct but comparable repertoire of ROS/RNS leading to two very distinct downstream responses.
authors.affiliation: Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: Anita
authors.initials: A
authors.lastname: Thakur
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: Md Jahangir
authors.initials: MJ
authors.lastname: Alam
authors.affiliation: School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
authors.forename: M R
authors.initials: MR
authors.lastname: Ajayakumar
authors.affiliation: Department of Zoology, University of Pune, Pune, India.
authors.forename: Saroj
authors.initials: S
authors.lastname: Ghaskadbi
authors.affiliation: Defence Institute of Physiology & Allied Sciences, New Delhi 110054, India.
authors.forename: Manish
authors.initials: M
authors.lastname: Sharma
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India. Electronic address: skgoswami@mail.jnu.ac.in.
authors.forename: Shyamal K
authors.initials: SK
authors.lastname: Goswami
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002374:Catalase / Q000378:metabolism; D002460:Cell Line; D004249:DNA Damage / Q000187:drug effects; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000032:analysis; D004797:Enzyme-Linked Immunosorbent Assay; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D008856:Microscopy, Fluorescence; D032386:Myoblasts, Cardiac / Q000166:cytology / Q000378:metabolism; D009638:Norepinephrine / Q000633:toxicity*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D017665:Hydroxyl Radical; D000080242:8-Hydroxy-2'-Deoxyguanosine; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D003849:Deoxyguanosine; D009638:Norepinephrine
keywords: 8−OH-dG; Apoptosis; Cardiac myocyte; Hypertrophy; Reactive oxygen species; Redox signaling