Ethanol induces vascular relaxation via redox-sensitive and nitric oxide-dependent pathways

• Published in: Vascular pharmacology 2012-01, Vol.56 (1), p.74-83
• Main Authors: Rocha, Juliana T, Hipólito, Ulisses V, Callera, Glaucia E, Yogi, Alvaro, Filho, Mario dos Anjos Neto, Bendhack, Lusiane M, Touyz, Rhian M, Tirapelli, Carlos R
• Format: Article
• Language: English
• Subjects: Animals; Aorta; Aorta - drug effects; Aorta - metabolism; Cardiovascular; Cells, Cultured; Cyclic GMP - metabolism; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Ethanol; Ethanol - pharmacology; Male; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Myocytes, Smooth Muscle - drug effects; Myocytes, Smooth Muscle - metabolism; Nitric oxide; Nitric Oxide - metabolism; Oxidation-Reduction; Rats; Rats, Wistar; Reactive oxygen species; Reactive Oxygen Species - metabolism; Relaxation; Signal Transduction - drug effects; Vasodilation - drug effects
• ISSN: 1537-1891; 1879-3649
• DOI: 10.1016/j.vph.2011.11.006

Abstract We investigated the role of reactive oxygen species (ROS) and nitric oxide (NO) in ethanol-induced relaxation. Vascular reactivity experiments showed that ethanol (0.03–200 mmol/L) induced relaxation in endothelium-intact and denuded rat aortic rings isolated from male Wistar rats. Pre-incubation of intact or denuded rings with l -NAME (non selective NOS inhibitor, 100 μmol/L), 7-nitroindazole (selective nNOS inhibitor, 100 μmol/L), ODQ (selective inhibitor of guanylyl cyclase enzyme, 1 μmol/L), glibenclamide (selective blocker of ATP-sensitive K+ channels, 3 μmol/L) and 4-aminopyridine (selective blocker of voltage-dependent K+ channels, 4-AP, 1 mmol/L) reduced ethanol-induced relaxation. Similarly, tiron (superoxide anion (O2− ) scavenger, 1 mmol/L) and catalase (hydrogen peroxide (H2 O2 ) scavenger, 300 U/mL) reduced ethanol-induced relaxation to a similar extent in both endothelium-intact and denuded rings. Finally, prodifen (non-selective cytochrome P450 enzymes inhibitor, 10 μmol/L) and 4-methylpyrazole (selective alcohol dehydrogenase inhibitor, 10 μmol/L) reduced ethanol-induced relaxation. In cultured aortic vascular smooth muscle cells (VSMCs), ethanol stimulated generation of NO, which was significantly inhibited by l -NAME. In endothelial cells, flow cytometry studies showed that ethanol increased cytosolic Ca 2 + concentration ([Ca 2 + ]c), O2- and cytosolic NO concentration ([NO]c). Tiron inhibited ethanol-induced increase in [Ca 2 + ]c and [NO]c. The major new finding of this work is that ethanol induces relaxation via redox-sensitive and NO–cGMP-dependent pathways through direct effects on ROS production and NO signaling. These findings identify putative molecular mechanisms whereby ethanol, at pharmacological concentrations, influences vascular reactivity.