Vascular responses to alpha1-adrenergic receptors in small rat mesenteric arteries depend on mitochondrial reactive oxygen species.
BACKGROUND
Agonists of G-protein-coupled receptors (eg, adrenoceptors and angiotensin receptors) signal, at least in part, through matrix metalloproteinases (such as matrix metalloproteinase [MMP]-7) that transactivate the epidermal growth factor receptor (EGFR). Focusing on adrenoceptors, we examined whether the MMP-dependent signaling pathway depends on reactive oxygen species (ROS).


RESULTS
In isolated rat mesenteric arteries, selective stimulation of alpha1-adrenoceptors with phenylephrine induced MMP transactivation of the EGFR, mitochondrial ROS production (detected by MitoTrackerRed-CM-H2XRos-fluorescence and dihydroethidium-fluorescence and high-performance liquid chromatography [HPLC]/MS assay) and vasoconstriction. Inhibition of the synthesis of either MMP-7 or EGFR with anti-sense or siRNA oligonucleotides, respectively, decreased mitochondrial ROS production in response to phenylephrine. Targeted mitochondrial ROS scavenging with MitoTrackerRed-CM-H2XRos inhibited adrenergic vasoconstriction. Adrenoceptor-induced ROS increased mitochondrial membrane potential (Deltapsim), which was prevented by blockers of MMPs (GM6001, doxycycline), EGFR (AG1478), or complex I, all of which also prevented ROS production as well as vasoconstriction.


CONCLUSIONS
Production of mitochondrial ROS is a new event in the pathway by which vasoactive agonists that induce MMP transactivation of the EGFR modulate vascular tone. Moreover, our findings suggest a connection between agonist-induced activity of MMPs, the promotion of oxidative stress, enhanced vascular tone, and hypertrophy, which are all implicated in the development and progression of vascular disease.
Hao
Li
L
Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
Nishimura
Tamiko
T
Wo
Hua
H
Fernandez-Patron
Carlos
C
D058646:Adrenergic alpha-1 Receptor Agonists; D000818:Animals; D004151:Dipeptides / Q000494:pharmacology; D004318:Doxycycline / Q000494:pharmacology; D066246:ErbB Receptors / Q000502:physiology; D066298:In Vitro Techniques; D020783:Matrix Metalloproteinase 7 / Q000502:physiology; D008638:Mesenteric Arteries / Q000502:physiology* / Q000648:ultrastructure; D008931:Mitochondria, Muscle / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D011799:Quinazolines; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects; D020032:Tyrphostins / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D058646:Adrenergic alpha-1 Receptor Agonists; D004151:Dipeptides; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011799:Quinazolines; D017382:Reactive Oxygen Species; D018340:Receptors, Adrenergic, alpha-1; D020032:Tyrphostins; D014662:Vasoconstrictor Agents; C101044:RTKI cpd; D010656:Phenylephrine; D066246:ErbB Receptors; D020783:Matrix Metalloproteinase 7; D004318:Doxycycline