title: Catecholamine-induced vascular wall growth is dependent on generation of reactive oxygen species.
abstract: Alpha1-adrenoceptor-dependent proliferation of vascular smooth muscle cells (VSMCs) is strongly augmented by vascular injury, and may contribute to intimal growth and lumen loss. Because reactive oxygen species (ROS) are increased by injury and have been implicated as second messengers in proliferation of VSMCs, we investigated the role of ROS in catecholamine-induced VSMC growth. Rat aortae were isolated 4 days after balloon injury, maintained in organ culture under circumferential wall tension, and exposed to agents for 48 hours. The antioxidants N-acetylcysteine (NAC, 10 mmol/L) and Tiron (5 mmol/L) and the flavin-inhibitor diphenylene iodonium (DPI, 20 micromol/L) abolished norepinephrine-induced increases in protein synthesis and DNA content in media. In aortic sections, norepinephrine augmented ROS production (dihydroethidium confocal microscopy), which was dose-dependently inhibited by NAC, Tiron, and DPI. In cultured VSMCs, phenylephrine caused time- and dose-dependent ROS generation (aconitase activity), had similar efficacy to thrombin (1 U/mL), and was eliminated by the superoxide dismutase (SOD) mimetic Mn-(III)-tetrakis-(4-benzoic-acid)-porphyrin-chloride (200 micromol/L) and Tiron. Phenylephrine-induced ROS production and increases in DNA and protein content were blocked by prazosin (0.3 micromol/L) and abolished in p47phox-/- cells. PEG-SOD (25 U/mL) had little effect, whereas PEG-catalase (50 U/mL) eliminated phenylephrine-induced proliferation in VSMCs. DPI (10 micromol/L) and apocynin (30 micromol/L) abolished phenylephrine-stimulated mitogenesis, whereas inhibitors of other intracellular ROS sources had not effect. Furthermore, PE increased p47phox expression (RT-PCR). These data demonstrate that the trophic effect of catecholamines on vascular wall cells is dependent on a ROS-sensitive step that we hypothesize consists of activation of the NAD(P)H-dependent vascular oxidase.
authors.affiliation: Department of Cell and Molecular Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7545, USA.
authors.forename: Tina
authors.initials: T
authors.lastname: Bleeke
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Nageswara
authors.initials: N
authors.lastname: Madamanchi
authors.forename: Cam
authors.initials: C
authors.lastname: Patterson
authors.forename: James E
authors.initials: JE
authors.lastname: Faber
mesh_terms: D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000800:Angioplasty, Balloon; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001011:Aorta / Q000166:cytology; D001157:Arterial Occlusive Diseases / Q000209:etiology / Q000378:metabolism; D002374:Catalase / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D009638:Norepinephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009924:Organ Culture Techniques; D010656:Phenylephrine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D010750:Phosphoproteins / Q000502:physiology; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D017540:Tunica Media / Q000166:cytology / Q000378:metabolism
chemical_list: D058646:Adrenergic alpha-1 Receptor Agonists; D000316:Adrenergic alpha-Agonists; D000975:Antioxidants; D004791:Enzyme Inhibitors; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D010656:Phenylephrine; D002374:Catalase; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D009638:Norepinephrine; D011224:Prazosin