Thioredoxin Reductase Inhibition Reduces Relaxation By Increasing Oxidative Stress and S-Nitrosylation in Mouse Aorta

Oxidative stress is well known to lead to vascular dysfunction. Thioredoxin reductase (TrxR) catalyzes the reduction of oxidized thioredoxin. Reduced thioredoxin plays a role in cellular antioxidative defense and in decreasing S-nitrosylation. It is not known whether TrxR affects vascular reactivity. We hypothesized that TrxR inhibition decreases vascular relaxation via increased oxidative stress and S-nitrosylation. Aortic rings from C57BL/6 mice were treated with the TrxR inhibitor, 1-chloro-2,4-dinitrobenzene (DNCB), or auranofin for 30 minutes. Vascular relaxation to acetylcholine was measured in the rings contracted with phenylephrine. DNCB and auranofin reduced relaxation compared with vehicle (vehicle E-max = 71 +/- 3%, DNCB E-max = 53 +/- 3%; P < 0.05). The antioxidants, apocynin (nicotinamide adenine dinucleotide phosphate oxidase inhibitor), and tempol (superoxide dismutase mimetic) normalized impaired relaxation by DNCB in aorta (DNCB E-max = 53 +/- 3%, DNCB + tempol E-max = 66 +/- 3%; P < 0.05). In addition, DNCB reduced sodium nitroprusside-induced relaxation. DNCB increased soluble guanylyl cyclase (sGC) S-nitrosylation and decreased sGC activity. These data suggest that TrxR regulates vascular relaxation via antioxidant defense and sGC S-nitrosylation. TrxR may be an enzyme to approach for treatment of vascular dysfunction and arterial hypertension.