scholarly journals The role of nitric oxide synthase-derived reactive oxygen species in the altered relaxation of pulmonary arteries from lambs with increased pulmonary blood flow

2007 ◽  
Vol 293 (3) ◽  
pp. H1491-H1497 ◽  
Author(s):  
Satyan Lakshminrusimha ◽  
Dean Wiseman ◽  
Stephen M. Black ◽  
James A. Russell ◽  
Sylvia F. Gugino ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Pulmonary Hypertension ◽  
Nitric Oxide Synthase ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Nitric Oxide Donor ◽  
Superoxide Anions ◽  
A 23187 ◽  
Oxide Synthase

Congenital cardiac defects associated with increased pulmonary blood flow (Qp) produce pulmonary hypertension. We have previously reported attenuated endothelium-dependent relaxations in pulmonary arteries (PA) isolated from lambs with increased Qp and pulmonary hypertension. To better characterize the vascular alterations in the nitric oxide-superoxide system, 12 fetal lambs underwent in utero placement of an aortopulmonary vascular graft (shunt). Twin lambs served as controls. PA were isolated from these lambs at 4–6 wk of age. Electron paramagnetic resonance spectroscopy on fourth-generation PA showed significantly increased superoxide anion generation in shunt PA that were decreased to control levels following inhibition of nitric oxide synthase (NOS) with 2-ethyl-2-thiopseudourea. Preconstricted fifth-generation PA rings were relaxed with a NOS agonist (A-23187), a nitric oxide donor [ S-nitrosyl amino penicillamine (SNAP)], polyethylene glycol-conjugated superoxide dismutase (PEG-SOD), or H2O2. A-23187-, PEG-SOD-, and H2O2-mediated relaxations were impaired in shunt PA compared with controls. Pretreatment with PEG-SOD significantly enhanced the relaxation response to A-23187 and SNAP in shunt but not control PA. Inhibition of NOS with nitro-l-arginine or scavenging superoxide anions with tiron enhanced relaxation to SNAP and inhibited relaxation to PEG-SOD in shunt PA. Pretreatment with catalase inhibited relaxation of shunt PA to A-23187, SOD, and H2O2. We conclude that NOS catalyzes the production of superoxide anions in shunt PA. PEG-SOD relaxes shunt PA by converting these anions to H2O2, a pulmonary vasodilator. The redox environment, influenced by the balance between production and scavenging of ROS, may have important consequences on pulmonary vascular reactivity in the setting of increased Qp.

scholarly journals Enhanced expression of nitric oxide synthase in the early stage after increased pulmonary blood flow in rats

2002 ◽  
Vol 21 (2) ◽  
pp. 331-336 ◽  
Author(s):  
Tsai-Fwu Chou ◽  
Ming-Shiou Wu ◽  
Chiang-Ting Chien ◽  
Chia-Cherng Yu ◽  
Chau-Fong Chen
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Nitric Oxide Synthase ◽  
Pulmonary Blood Flow ◽  
Early Stage ◽  
Enhanced Expression ◽  
Oxide Synthase

Oxidant stress from uncoupled nitric oxide synthase impairs vasodilation in fetal lambs with persistent pulmonary hypertension

2007 ◽  
Vol 292 (4) ◽  
pp. H1812-H1820 ◽  
Author(s):  
Girija G. Konduri ◽  
Ivane Bakhutashvili ◽  
Annie Eis ◽  
Kirkwood Pritchard
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Nitric Oxide Synthase ◽  
Pulmonary Artery ◽  
Ductus Arteriosus ◽  
Oxidant Stress ◽  
Pulmonary Arteries ◽  
Persistent Pulmonary Hypertension ◽  
Pulmonary Vasodilation ◽  
Oxide Synthase

Persistent pulmonary hypertension of newborn (PPHN) is associated with decreased NO release and impaired pulmonary vasodilation. We investigated the hypothesis that increased superoxide (O2•−) release by an uncoupled endothelial nitric oxide synthase (eNOS) contributes to impaired pulmonary vasodilation in PPHN. We investigated the response of isolated pulmonary arteries to the NOS agonist ATP and the NO donor S-nitroso- N-acetylpenicillamine (SNAP) in fetal lambs with PPHN induced by prenatal ligation of ductus arteriosus and in sham-ligated controls in the presence or absence of the NOS antagonist nitro-l-arginine methyl ester (l-NAME) or the O2•− scavenger 4,5-dihydroxy-1,3-benzenedisulfonate (Tiron). ATP caused dose-dependent relaxation of pulmonary artery rings in control lambs but induced constriction of the rings in PPHN lambs. l-NAME, the NO precursor l-arginine, and Tiron restored the relaxation response of pulmonary artery rings to ATP in PPHN. Relaxation to NO was attenuated in arteries from PPHN lambs, and the response was improved by l-NAME and by Tiron. We also investigated the alteration in heat shock protein (HSP)90-eNOS interactions and release of NO and O2•− in response to ATP in the pulmonary artery endothelial cells (PAEC) from these lambs. Cultured PAEC and endothelium of freshly isolated pulmonary arteries from PPHN lambs released O2•− in response to ATP, and this was attenuated by the NOS antagonist l-NAME and superoxide dismutase (SOD). ATP stimulated HSP90-eNOS interactions in PAEC from control but not PPHN lambs. HSP90 immunoprecipitated from PPHN pulmonary arteries had increased nitrotyrosine signal. Oxidant stress from uncoupled eNOS contributes to impaired pulmonary vasodilation in PPHN induced by ductal ligation in fetal lambs.

Altered endothelium-dependent relaxations in lambs with high pulmonary blood flow and pulmonary hypertension

2001 ◽  
Vol 280 (1) ◽  
pp. H311-H317 ◽  
Author(s):  
Robin H. Steinhorn ◽  
James A. Russell ◽  
Satyan Lakshminrusimha ◽  
Sylvia F. Gugino ◽  
Stephen M. Black ◽  
...  
Keyword(s):  
Blood Flow ◽  
Pulmonary Hypertension ◽  
Vascular Graft ◽  
Pulmonary Blood Flow ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Veins ◽  
Pulmonary Arteries ◽  
No Synthase ◽  
A 23187 ◽  
Endothelium Dependent Relaxation

Congenital heart disease associated with increased pulmonary blood flow produces pulmonary hypertension. To characterize vascular alterations in the nitric oxide (NO)-cGMP cascade induced by increased pulmonary blood flow and pulmonary hypertension, 10 fetal lambs underwent in utero placement of an aortopulmonary vascular graft (shunt). When the lambs were 4–6 wk of age, we assessed responses of pulmonary arteries (PAs) and pulmonary veins (PVs) isolated from lungs of control and shunted lambs. PVs from control and shunted lambs relaxed similarly to exogenous NO ( S-nitrosyl-acetyl-penicillamine), to NO produced endogenously (zaprinast and A-23187), and to cGMP (atrial natriuretic peptide). In contrast, relaxations to A-23187 and zaprinast were blunted in PAs isolated from shunted lambs relative to controls. Inhibitors of NO synthase (NOS) and soluble guanylate cyclase constricted control but not shunt PAs, indicating reduced basal NOS activity in shunt PAs. Pretreatment of shunt PAs with the substratesl-arginine and sepiapterin, a precursor for tetrahydrobiopterin synthesis, did not augment A-23187 relaxations. However, pretreatment with superoxide dismutase and catalase significantly enhanced A-23187 relaxations in shunt PAs. We conclude that increased pulmonary blood flow induces an impairment of endothelium-dependent relaxation that is selective to PAs. The impaired relaxation may be mediated in part by excess superoxide production.

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