Upregulation of Arginase by H₂O₂Impairs Endothelium-Dependent Nitric Oxide-Mediated Dilation of Coronary Arterioles

Abstract

Objective-Overproduction of reactive oxygen species such as hydrogen peroxide (H 2 O 2 ) has been implicated in various cardiovascular diseases. However, mechanism(s) underlying coronary vascular dysfunction induced by H 2 O 2 is unclear. We studied the effect of H 2 O 2 on dilation of coronary arterioles to endothelium-dependent and endothelium-independent agonists. Methods and Results-Porcine coronary arterioles were isolated and pressurized without flow for in vitro study. All vessels developed basal tone and dilated dose-dependently to activators of nitric oxide (NO) synthase (adenosine and ionomycin), cyclooxygenase (arachidonic acid), and cytochrome P450 monooxygenase (bradykinin). Intraluminal incubation of vessels with H 2 O 2 (100 mol/L, 60 minutes) did not alter basal tone but inhibited vasodilations to adenosine and ionomycin in a manner similar as that by NO synthase inhibitor L-NAME. H 2 O 2 affected neither endothelium-dependent responses to arachidonic acid and bradykinin nor endothelium-independent dilation to sodium nitroprusside. The inhibited adenosine response was not reversed by removal of H 2 O 2 but was restored by excess L-arginine. Inhibition of L-arginine consuming enzyme arginase by ␣-difluoromethylornithine or N -hydroxy-nor-Larginine also restored vasodilation. Administering deferoxamine, an inhibitor of hydroxyl radical production, prevented the H 2 O 2 -induced impairment of vasodilation to adenosine. Western blot and reverse-transcription polymerase chain reaction results indicated that arginase I was upregulated after treating vessels with H 2 O 2 . Key Words: endothelium Ⅲ free radicals Ⅲ hydrogen peroxide Ⅲ nitric oxide R eactive oxygen species (ROS) from mitochondria and other subcellular sources have been regarded as toxic byproducts of metabolism, especially when excessive production of ROS outstrips endogenous antioxidant defense mechanisms. 1 However, ROS are also known to influence the expression of a number of genes and signal transduction pathways 2 and are thought to act as subcellular messengers for certain growth factors. 3 Interestingly, several cardiovascular diseases with diverse etiologies, such as atherosclerosis, 4 hypertension, 5 vascular complications in diabetes, 6 and after ischemia/reperfusion injury 7 are associated with the common hallmarks of increased oxidative stress and endothelial cell dysfunction. 8 Although the molecular basis of endothelial dysfunction is not completely understood, numerous studies point to the reduction of nitric oxide (NO) biosynthesis and/or bioactivity as a major mechanism. 9 However, the underlying cellular mechanisms contributing to the reduction of NO-mediated effects remain unclear. Conclusions-H See page 1931Perfusion of coronary artery with H 2 O 2 has recently been shown to impair vasodilation in response to NO-mediated agonists; 10 however, the studies suggested that endothelial dysfunction caused by H 2 O 2 was not mediated by the disruption of arginine-NO pathway. 11 In fact, NO synthase (NOS) activity and its exp...

Selective Activation of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Mediates C-Reactive Protein–Evoked Endothelial Vasodilator Dysfunction in Coronary Arterioles

“…It has been shown that hydrogen peroxide, a downstream product from superoxide dismutase, can impair vasomotor function. 29,46 Inhibition of hydrogen peroxide formation by cell-permeable polyethylene-glycolated catalase has been reported to prevent hydrogen peroxide signaling in the vasculature. 47 To determine whether hydrogen peroxide contributed to the observed vascular dysfunction in our study, the vessels were pretreated with this modified catalase, and the effect of CRP was subsequently investigated.…”

“…The roles of LOX-1 and CD32 in mediating the CRP effect were examined in a separate group of vessels by determining dilation to serotonin before and after coadministration of CRP with an anti-LOX-1 antibody (5 µg/mL; Abcam) 25 or an anti-CD32 antibody (5 µg/mL; Santa Cruz Biotechnology). 26,27 κ-Carrageenan (125 µg/mL), a LOX-1 antagonist, 25,28 and catalase (1000 U/mL), 29,30 the hydrogen peroxide scavenger, were administered to determine the role of LOX-1 and hydrogen peroxide, respectively, in the observed CRP effect. In another cohort of vessels, vasodilation to arachidonic acid (10 µmol/L), 10 an endothelium-dependent PGI 2 -mediated agonist, was examined before and after incubation with PGI 2 synthase inhibitor trans-2-phenyl cyclopropylamine (TPC; 100 µmol/L) 10 or after 60-minute intraluminal incubation with recombinant CRP (7 µg/mL) in the absence or presence of an anti-LOX-1 antibody (5 µg/ mL), TPC plus an anti-LOX-1 antibody, or an anti-CD32 antibody (5 µg/mL).…”

“…In these endothelium-denuded vessels, the vasodilation to serotonin (0.1 µmol/L) was abolished (control: 63±4% dilation versus denudation: 3±1% dilation; n=4), and the endotheliumindependent vasodilation to sodium nitroprusside (10 µmol/L) was unaltered (control: 85±6% dilation versus denudation: 80±9% dilation; n=4). In the presence of an effective concentration of catalase, 29,30 a scavenger of hydrogen peroxide, the inhibitory effect of CRP on vasodilation to serotonin remained (Online Figure II).…”

Cellular mediators of renal vascular dysfunction in hypertension

“…Endothelial cell dysfunction may also involve increased arginase activity, which converts L-arginine to L-ornithine and urea, thus decreasing the substrate for NO production (76). H 2 O 2 upregulates arginase activity and thereby may impair renal vasodilatation (170).…”

Aging impairs flow-induced dilation in coronary arterioles: role of NO and H2O2

“…Elevated levels of non-heme iron may increase conversion of H 2 O 2 to OH • , contributing to an overall decline in flow-mediated dilation with aging. Furthermore, previous reports have suggested that hydroxyl may contribute to reduced NO-mediated vasodilation (45). We examined flowmediated dilation in the presence of Tempol plus deferoxamine, an iron chelator and inhibitor of OH…”