title: Reactive oxygen species from smooth muscle mitochondria initiate cold-induced constriction of cutaneous arteries.
abstract: Cold constricts cutaneous blood vessels by selectively increasing the activity of smooth muscle alpha2-adrenoceptors (alpha2-ARs). In mouse tail arteries, alpha2-AR constriction is mediated by alpha2A-ARs at 37 degrees C, whereas the cold-induced augmentation in alpha2-AR activity is mediated entirely by alpha2C-ARs. Cold causes translocation of alpha2C-ARs from the trans-Golgi to the plasma membrane, mediated by cold-induced activation of RhoA and Rho kinase. The present experiments analyzed the mechanisms underlying these responses. Mouse tail arteries were studied in a pressure myograph. Cooling the arteries (28 degrees C) caused a rapid increase in reactive oxygen species (ROS) in smooth muscle cells, determined by confocal microscopy of arteries loaded with the ROS-sensitive probes, dichlorodihydrofluorescein or reduced Mitotracker Red. The inhibitor of mitochondrial complex I rotenone (10 micromol/l), the antioxidant N-acetylcysteine (NAC; 20 mmol/l), or the cell-permeable mimic of superoxide dismutase MnTMPyP (50 micromol/l) did not affect vasoconstriction to alpha2-AR stimulation (UK-14304) at 37 degrees C but dramatically inhibited the response at 28 degrees C. Indeed, these ROS inhibitors abolished the cold-induced increase in alpha2-AR constrictor activity. NAC (20 mmol/l) or MnTMPyP (50 micromol/l) also abolished the cold-induced activation of RhoA in human cultured vascular smooth muscle cells and the cold-induced mobilization of alpha2C-ARs to the cell surface in human embryonic kidney 293 cells transfected with the receptor. The combined results suggest that cold-induced constriction is mediated by redox signaling in smooth muscle cells, initiated by mitochondrial generation of ROS, which stimulate RhoA/Rho kinase signaling and the subsequent mobilization of alpha2C-ARs to the cell surface. Altered activity of ROS may contribute to cold-induced vasospasm occurring in Raynaud's phenomenon.
authors.affiliation: Davis Heart and Lung Research Institute, R 110E, The Ohio State Univ., 473 West 12th Ave, Columbus, OH 43210, USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Bailey
authors.forename: S
authors.initials: S
authors.lastname: Mitra
authors.forename: S
authors.initials: S
authors.lastname: Flavahan
authors.forename: N A
authors.initials: NA
authors.lastname: Flavahan
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001158:Arteries / Q000502:physiology; D001692:Biological Transport; D002460:Cell Line; D002478:Cells, Cultured; D003080:Cold Temperature; D042967:Electron Transport Complex I / Q000037:antagonists & inhibitors; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008931:Mitochondria, Muscle / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D012867:Skin / Q000098:blood supply*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000502:physiology
chemical_list: D000975:Antioxidants; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D018341:Receptors, Adrenergic, alpha-2; D012402:Rotenone; D020742:rhoA GTP-Binding Protein; D042967:Electron Transport Complex I; D000111:Acetylcysteine