Oxide Synthase In Endothelial Cells Research Articles

Arterial endothelial dysfunction in baboons fed a high-cholesterol, high-fat diet

Endothelial dysfunction signals the initiation and progression of atherosclerosis. Elevated LDL-cholesterol concentrations have been suggested to induce endothelial dysfunction, but direct in vivo evidence for the relation is still lacking. We examined the hypothesis that a high-cholesterol, high-fat (HCHF) diet can directly cause endothelial dysfunction in vivo. We measured inflammatory and endothelial dysfunctional markers in circulating blood and directly in endothelial cells, which were collected by femoral artery biopsies, in 10 baboons before and after a 7-wk HCHF dietary challenge. We found that the HCHF diet induced a high inflammatory status, as indicated by increased concentrations of interleukin 6, tumor necrosis factor alpha (TNF-alpha), and monocyte chemoattractant protein 1. Although the concentrations of endothelial dysfunctional markers, such as soluble vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1, were not increased by the HCHF diet, membrane-bound VCAM-1 and membrane-bound E-selectin on endothelial cells were highly increased after 7 wk of the HCHF diet (P < 0.01). In contrast, the concentrations of endothelial nitric oxide synthase in endothelial cells were significantly reduced by the 7-wk HCHF diet (P < 0.01). Furthermore, the dietary challenge attenuated endothelial cell responses to TNF-alpha, lipopolysaccharide, native LDL cholesterol, and oxidized LDL-cholesterol stimulation. Our results show that an HCHF diet can directly induce inflammation and endothelial dysfunction. Prior in vivo exposure to an HCHF diet attenuates the in vitro responses of endothelial cells to atherogenic risk factors. This preconditioning phenomenon may have significant clinical relevance.

The role of nitric oxide in mitochondria. Focus on “Modulation of mitochondrial Ca2+ by nitric oxide in cultured bovine vascular endothelial cells”

nitric oxide (NO) plays an important role in intracellular signaling, and stole the limelight in 1992 by winning science's equivalent of an “Oscar”: Science magazine's “Molecule of the Year.” Subsequently, the importance and versatility of its known roles has expanded. Furthermore, this

The Ets transcription factor ESE‐1 mediates induction of the COX‐2 gene by LPS in monocytes

Cyclooxygenase-2 (COX-2) is a key enzyme in the production of prostaglandins that are major inflammatory agents. COX-2 production is triggered by exposure to various cytokines and to bacterial endotoxins. We present here a novel role for the Ets transcription factor ESE-1 in regulating the COX-2 gene in response to endotoxin and other pro-inflammatory stimuli. We report that the induction of COX-2 expression by lipopolysaccharide (LPS) and pro-inflammatory cytokines correlates with ESE-1 induction in monocyte/macrophages. ESE-1, in turn, binds to several E26 transformation specific (Ets) sites on the COX-2 promoter. In vitro analysis demonstrates that ESE-1 binds to and activates the COX-2 promoter to levels comparable to LPS-mediated induction. Moreover, we provide results showing that the induction of COX-2 by LPS may require ESE-1, as the mutation of the Ets sites in the COX-2 promoter or overexpression of a dominant-negative form of ESE-1 inhibits LPS-mediated COX-2 induction. The effect of ESE-1 on the COX-2 promoter is further enhanced by cooperation with other transcription factors such as nuclear factor-kappa B and nuclear factor of activated T cells. Neutralization of COX-2 is the goal of many anti-inflammatory drugs. As an activator of COX-2 induction, ESE-1 may become a target for such therapeutics as well. Together with our previous reports of the role of ESE-1 as an inducer of nitric oxide synthase in endothelial cells and as a mediator of pro-inflammatory cytokines in vascular and connective tissue cells, these results establish ESE-1 as an important player in the regulation of inflammation.

Why Do Anal Wounds Heal Adequately? A Study of the Local Immunoinflammatory Defense Mechanisms

The aim of this study was to identify the tissue defense immunoinflammatory mechanisms present in the healing process of anal region wounds resulting from hemorrhoidectomy by the open technique. Immunohistochemical techniques were applied to biopsies of anal wounds obtained on Day 0 and Day 6 after surgery from 20 patients with hemorrhoid disease to characterize and quantify macrophages, T and B lymphocytes, and natural killer cells in high-power fields (400x). These techniques were also used to identify cells showing immunoexpression of cytokines (transforming growth factor beta 1, transforming growth factor beta 2, transforming growth factor beta 3) and constitutive and induced nitric oxide synthase. Plasma cells were quantified on slides stained with hematoxylin and eosin and the presence of immunoglobulin G, immunoglobulin M, and immunoglobulin A secreting cells was investigated by direct immunofluorescence. An acute nonspecific inflammation with no lymphomononuclear-plasmacytic component was observed on Day 0. On Day 6, an inflammatory cellular infiltration rich in macrophages and lymphoplasmacytic cells was detected, which documented the participation of innate defense mechanisms and the adaptive tissue response. On Day 6, the mean number of immunoinflammatory cells were as follows: macrophages (CD68+) = 190.3; macrophages (HAM56+) = 184.3; T lymphocytes (CD3+) = 59.6; T lymphocytes (CD45RO+) = 47.7; helper T lymphocytes (CD4+) = 89.2; cytotoxic T lymphocytes (CD8+) = 29.4; B lymphocytes (CD20+) = 64.4; plasma cells = 1.7; natural killer cells (NK1+) = 12.9. Macrophages (HAM56+ and CD68+) were present in significantly higher amounts than those of the remaining ones. B lymphocytes (CD20+) predominated over T lymphocytes (CD3+), although the difference between the two cell types was not significant. Participation of the humoral immune system was characterized by the presence of immunoglobulin G-secreting cells. The cellular immune system was characterized by the identification of T lymphocytes (CD3+ and CD45RO+), most of them belonging to the T helper cell subpopulation (CD4+). These predominated in a significant manner over cytotoxic T lymphocytes (CD8+). Natural killer cells were present in small amounts. There was immunoexpression of constitutive nitric oxide synthase on Day 0 and on Day 6. Induced nitric oxide synthase was not identified on Day 0 but was present on Day 6. Transforming growth factor beta 2 and transforming growth factor beta 3 were expressed in endothelial cells on Day 0 and on Day 6, and transforming growth factor beta was also expressed in macrophages, endothelial cells, and fibroblasts on Day 6. Transforming growth factor beta 1 and transforming growth factor beta 2 were expressed significantly in macrophages, whereas transforming growth factor beta 3 occurred at similar proportions in the three cell types. The host developed locally innate and immunologic defense adaptive mechanisms. The predominant local defense response involved macrophages. Natural killer cells and immunoexpression of constitutive nitric oxide synthase in endothelial cells were components of the noninduced innate response. In the induced innate response, in addition to neutrophils, there were large numbers of macrophages that were the major cells showing immunoexpression of transforming growth factor beta and induced nitric oxide synthase. The adaptive immunologic response was characterized by T and B lymphocytes. Helper T cells and cytotoxic T cells predominated in the cellular immune response and cytotoxic T cells and natural killer cells were present in small numbers. Secretory immunoglobulin G plasma cells were present in small numbers as a component of the humoral immune system.

Effects of 5-fluorouracil on endothelial nitric oxide synthase in endothelial cells in different states of confluence

Effects of 5-fluorouracil on endothelial nitric oxide synthase in endothelial cells in different states of confluence

Effects of 5-fluorouracil on endothelial nitric oxide synthase in endothelial cells in different states of confluence

3149 Background: Some studies suggest a direct effect of 5-fluoruracil (5-FU) on vascular endothelium. The enzyme endothelial nitric-oxide synthase (eNOS) produces nitric oxide (NO) in the endothelium. It is known that NO has multiple physiological functions one of which is involved in the interaction of circulating tumour cells with the endothelium. On the other hand, endothelial cells (E.C) can be found in two different states of proliferation: confluence (quiescent) and subconfluence (proliferating). Our objetives are to study the effect of 5-FU on the eNOS expression and to analyse if there is a direct relationship between the effect of 5-FU and eNOs expression and the state of endothelial growth. Methods: Culture of bovine aortal endothelial cells (B.A.E.C). The dosage of 5-FU was 20 ugr/mL. The enzyme eNOS was measured using Western-blot method. Results: We observed an increase in eNOs expression in subconfluent E.C with respect to confluent E.C (14.6 densitometric units as opposed 8.97 DU;p<0.003; ...

1122-168 Urotensin II modulates collagen synthesis and the expression of matrix metallproteinase-1 and nitric oxide synthase in endothelial cells

1122-168 Urotensin II modulates collagen synthesis and the expression of matrix metallproteinase-1 and nitric oxide synthase in endothelial cells

Induction of vasorelaxation through activation of nitric oxide synthase in endothelial cells by brazilin

The vasorelaxant activity of Caesalpinia sappan L., a traditional Chinese medicine, and its major component brazilin were investigated in isolated rat aorta and human umbilical vein endothelial cells. In isolated rat aorta, C. sappan L. extract and brazilin relaxed phenylephrine-induced vasocontraction and increased cyclic guanosine 3′,5′-monophosphate (cGMP) content. Induction of vasorelaxation of brazilin was endothelium-dependent and could be markedly blocked by pretreatment with nitric oxide synthase (NOS) inhibitor, N G-nitro- l-arginine methyl ester ( l-NAME); N G-monomethyl- l-arginine acetate ( l-NMMA) and guanylyl cyclase inhibitor, methylene blue; 1 H-[1,2,4]oxadiazolo[4,3- a]quinoxalin-1-one (ODQ) and nitric oxide (NO) scavenger, hemoglobin. The increasing cGMP content induced by brazilin was also blocked by pretreatment with l-NAME, methylene blue, and the removal of extracellular Ca 2+. In human umbilical vein endothelial cells, brazilin dose-dependently induced an increase in NO formation and NOS activity, which were greatly attenuated by either the removal of extracellular Ca 2+ or the chelating of intracellular Ca 2+ chelator, 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid (BAPTA-AM). Moreover, brazilin dose-dependently induced the influx of extracellular Ca 2+ in human umbilical vein endothelial cells. Collectively, these results suggest that brazilin induces vasorelaxation by the increasing intracellular Ca 2+ concentration in endothelial cells of blood vessels and hence activating Ca 2+/calmodulin-dependent NO synthesis. The NO is released and then transferred into smooth muscle cells to activate guanylyl cyclase and increase cGMP content, resulting in vasorelaxation.

Overexpression of Endothelial Nitric Oxide Synthase in Endothelial Cells Is Protective against Ischemia-Reperfusion Injury in Mouse Skeletal Muscle

Microvascular injury has been proposed to be a main cause of ischemia-reperfusion (I/R) injury. The roles of endothelial nitric oxide synthase (eNOS)-derived NO, a key regulator of vascular function, in I/R injury are incompletely understood. We used transgenic mice overexpressing eNOS in endothelial cells (eNOS-Tg) and their littermates wild-type mice (WT) to investigate the roles of eNOS in I/R injury in skeletal muscle. Superoxide levels in the affected muscles were reduced by approximately 50% in eNOS-Tg compared with WT during reperfusion. In WT, the disassembly of endothelial junctional proteins seen in the early period of reperfusion was recovered in the later phase. These findings were correlated with the increased vascular permeability in vivo. In contrast, eNOS-Tg maintained the endothelial junction assembly as well as vascular permeability during reperfusion. Leukocyte extravasation into tissue and up-regulated expression of adhesion molecules in the reperfused vessels were significantly inhibited in eNOS-Tg. Tissue viability of the affected muscle was decreased in WT time-dependently after reperfusion, whereas eNOS-Tg showed no significant reduction. NOS inhibition completely reversed these protective effects of eNOS overexpression in I/R injury. Thus, eNOS overexpression appears to prevent the I/R injury in skeletal muscle by maintaining vascular integrity.

Inhibition by ginkgolides and bilobalide of the production of nitric oxide in macrophages (THP-1) but not in endothelial cells (HUVEC)

Nitric oxide (NO) is a principal mediator in many physiological and pathological processes. NO produced by constitutive nitric oxide synthase in endothelial cells (eNOS) acts as a vasodilator, whereas excess NO production due to elevated expression of inducible nitric oxide synthase (iNOS) may produce cytotoxic effects to cells in the vascular wall. We demonstrated in our previous work that the extract of Ginkgo biloba leaves (EGb) inhibits iNOS-mediated NO production. The objective of the present study was to investigate the effects of several active EGb components on iNOS-mediated NO production in macrophages derived from a human monocytic cell line (THP-1), as well as on eNOS-mediated NO production in human umbilical vein endothelial cells (HUVEC). Ginkgolide A, ginkgolide B, or bilobalide (0.25 to 1.0 μg/mL) caused a 30–65% reduction in the levels of NO metabolites released by THP-1 macrophages after 4 hr of incubation, with a corresponding decrease in iNOS activity. Western immunoblotting analysis coupled with a nuclease protection assay and reverse transcription–polymerase chain reaction revealed a concomitant reduction in the levels of iNOS protein mass and mRNA in ginkgolide A-, ginkgolide B-, or bilobalide-treated macrophages. On the other hand, these compounds did not affect eNOS-mediated NO production or the expression of eNOS protein and mRNA in HUVEC. Taken together, these results suggest that ginkgolide A, ginkgolide B, and bilobalide may contribute to the selective inhibitory effect of EGb on iNOS expression without affecting eNOS-mediated NO production.

Expression of nitric oxide synthase in endothelial cells is mediated by bilobalide and ginkgolide A

Expression of nitric oxide synthase in endothelial cells is mediated by bilobalide and ginkgolide A

Akt Takes Center Stage in Angiogenesis Signaling

The serine/threonine kinase Akt, also named protein kinase B, plays a central role in promoting the survival of a wide range of cell types.1 In this issue of Circulation Research , Kim et al2 report that angiopoietin-1 (Ang1) activates this survival kinase and thereby inhibits endothelial cell apoptosis. Ang1 was recently identified as the specific ligand for the Tie receptor family, which during embryonic blood vessel formation is required for vascular remodeling and vessel integrity.3 Mechanistically, Ang1 acts via stimulation of the Tie2 receptor. Upon activation, tyrosine phosphorylation of the Tie2 receptor (most probably at Tyr 11014 ) induces the association and activation of the phosphatidylinositol 3′kinase with subsequent activation of Akt.2 These findings complement previous studies, which demonstrated that vascular endothelial growth factor (VEGF) via the KDR/Flt-1 receptor also stimulates Akt and thereby promotes endothelial cell survival.5 6 Moreover, potent inhibitors of endothelial cell apoptosis such as shear stress or insulin activate Akt.7 8 Thus, activation of Akt seems to be a general antiapoptotic mechanism induced by proangiogenic stimuli. Because apoptosis of endothelial cells counteracts angiogenesis, one may …

Inhibitory effect of Ginkgo biloba extract on the expression of inducible nitric oxide synthase in endothelial cells

Excessive production of nitric oxide (NO) may have cytotoxic effects through the formation of peroxynitrite with superoxide. The extract of Ginkgo biloba leaves (EGb) has been demonstrated to be a potent scavenger of free radicals. Although EGb has been shown recently to inhibit NO production in macrophages, its effect on NO production in endothelial cells is largely unknown. The objective of this study was to elucidate the mechanism by which EGb affects NO production in a human endothelial cell line (ECV304). After cells were incubated with EGb (10–100 μg/mL) for 2 or 4 hr, the amounts of NO metabolites released by the cells were quantitated, and cellular NOS activities were determined following the conversion of [ 3H]arginine to [ 3H]citrulline. NOS protein expression was determined by western immunoblotting analysis. mRNA levels were examined by reverse transcription–polymerase chain reaction (RT–PCR) analysis. EGb (50 μg/mL) caused a 30% reduction of NO metabolites released by endothelial cells. Following EGb treatment, cellular inducible NO synthase (iNOS) activity was reduced by 28% with a concomitant reduction in the levels of iNOS protein mass and mRNA. There was no change in the activity or protein mass of constitutive NO synthase in these cells. EGb inhibited NO production by attenuating the level of iNOS mRNA in ECV304 cells. Selective inhibition of iNOS by EGb may be therapeutically relevant in modulating NO production in endothelial cells.

Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation.

Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) is a fundamental determinant of cardiovascular homesotasis: it regulates systemic blood pressure, vascular remodelling and angiogenesis. Physiologically, the most important stimulus for the continuous formation of NO is the viscous drag (shear stress) generated by the streaming blood on the endothelial layer. Although shear-stress-mediated phosphorylation of eNOS is thought to regulate enzyme activity, the mechanism of activation of eNOS is not yet known. Here we demonstrate that the serine/threonine protein kinase Akt/PKB mediates the activation of eNOS, leading to increased NO production. Inhibition of the phosphatidylinositol-3-OH kinase/Akt pathway or mutation of the Akt site on eNOS protein (at serine 1177) attenuates the serine phosphorylation and prevents the activation of eNOS. Mimicking the phosphorylation of Ser 1177 directly enhances enzyme activity and alters the sensitivity of the enzyme to Ca2+, rendering its activity maximal at sub-physiological concentrations of Ca2+. Thus, phosphorylation of eNOS by Akt represents a novel Ca2+-independent regulatory mechanism for activation of eNOS.

Differential effect of 2-aminoethyl-isothiourea, an inhibitor of the inducible nitric oxide synthase, on microvascular blood flow and organ injury in models of hepatic ischemia-reperfusion and endotoxemia.

The vasodilator nitric oxide (NO) is involved in the regulation of systemic blood pressure and local organ blood flow. Inhibitors of the constitutively expressed nitric oxide synthase in endothelial cells (eNOS), e.g., Nomega-nitro-L-arginine methyl ester hydrochloride (L-NAME), aggravated liver injury in a variety of models. On the other hand, inhibitors of the inducible NOS (iNOS), e.g., 2-aminoethyl-isothiourea (AET), were found to be beneficial during endotoxemia. The aim of this investigation was to study the effect of AET compared with L-NAME on liver microvascular blood flow and injury in more complex models with multiple insults, i.e., ischemia (20 min)-reperfusion (8 h) in combination with .5 mg/kg endotoxin (IRE). Male Fisher rats were treated with 10 mg/kg AET or L-NAME and subjected to IRE. At 8 h, liver injury (plasma ALT: 1320+/-164 U/L) was significantly increased in AET-treated (5,018+/-1,379 U/L) and L-NAME-treated groups (2,429+/-228 U/L). Each inhibitor attenuated microvascular blood flow (assessed by laser Doppler flowmetry) to a similar degree. In striking contrast, AET completely reversed the endotoxin-induced impairment of the microvascular blood flow and significantly protected against an endotoxin-induced liver injury (plasma ALT: 3,007+/-268 U/L (ET); 460+/-39 U/L (ET+AET)). Infusion of endothelin-1 reduced microvascular blood flow by 50-60% and caused liver injury. Our data demonstrated that an inhibitor of eNOS (L-NAME) has a consistent detrimental effect on liver injury during ischemia-reperfusion and endotoxemia mainly because it can cause additional ischemia by reducing the microvascular blood flow. However, selective inhibitors of iNOS (AET) can impair hepatic blood flow and aggravate the injury or improve blood flow and attenuate organ injury depending on the experimental model. These results suggest that iNOS inhibitors may not be universally beneficial and should be tested in a variety of experimental models of sepsis/endotoxemia before used in clinical settings.

Rapid Reversibility of Nitric Oxide Induced Platelet Inhibition

Nitric oxide is known to attenuate human platelet activation. Mechanistically this is achieved by stimulation of soluble guanylyl cyclase, followed by cGMP production, and concomitant protein phosphorylation. Although inhibitory actions of nitric oxide on various platelet parameters are well documented, considerably less information is available on the reversibility of this effect. In order to study the onset of proaggregatory signaling pathways after ceasing nitric oxide generation we used the nitric oxide-donor sodium nitroprusside in combination with cyanide. For sodium nitroprusside the generation of nitric oxide requires the release of cyanide prior to nitric oxide. Furthermore, the addition of exogenous cyanide blocks nitric oxide liberation from the nitric oxide-donor. Our data indicate, that the inhibitory potency of sodium nitroprusside on platelet aggregation, calcium mobilization, and a cGMP increase is reversed by cyanide addition. We put special attention to nitric oxide-mediated cGMP increase, followed by the extreme rapid cGMP degradation after cyanide administration followed by the onset of major proaggregatory signaling pathways. Our study aims at the physiological importance of a permanently active, probably shear stress induced nitric oxide-synthase in endothelial cells that functions as a negative thromboregulatory mechanism.

Induction of nitric oxide synthase in endothelial cells: Different molecular mechanisms for UVA and UVB irradiation

Induction of nitric oxide synthase in endothelial cells: Different molecular mechanisms for UVA and UVB irradiation

Effects of Halothane and Isoflurane on Bradykinin-evoked Calcium2+Influx in Bovine Aortic Endothelial Cells

Volatile anesthetics, such as halothane and isoflurane, have been reported to affect the endothelium mediated relaxation of vascular smooth muscle cells. Because the activity of the constitutive nitric oxide synthase in endothelial cells depends on the availability of intracellular Ca2+, there is a definite possibility that the observed inhibitory effect of volatile anesthetics involves an action on the agonist-evoked internal Ca2+ mobilization and/or Ca2+ influx in these cells. Therefore, a study was undertaken to determine how halothane and isoflurane affect the Ca2+ signalling process in vascular endothelial cells. The effect of halothane and isoflurane on the Ca2+ response to bradykinin of bovine aortic endothelial (BAE) cells was investigated using the fluorescent Ca2+ indicator fura-2. Halothane or isoflurane was applied either to resting cells or after bradykinin stimulation. The agonist-evoked Ca2+ influx in BAE cells was estimated by measuring either the rate of fura-2 quenching induced by Mn2+ or the increase in cytosolic Ca2+ concentration initiated after readmission of external Ca2+ after a brief exposure of the cells to a Ca(2+)-free external medium. The effects of halothane on cell potential and intracellular Ca2+ concentration were measured in cell-attached patch-clamp experiments in which a calcium-activated K+ channel and an inward rectifying Ca(2+)-independent K+ channel were used as probes to simultaneously monitor the intracellular Ca2+ concentration and the cell transmembrane potential. In addition, combined fura-2 and patch-clamp cell-attached recordings were carried out, to correlate the variations in internal Ca2+ caused by halothane and the activity of the Ca(2+)-dependent K+ channels, which are known in BAE cells to regulate intracellular potential. Finally, a direct action of halothane and isoflurane on the gating properties of the Ca(2+)-activated K+ channel present in these cells was investigated in patch-excised inside-out experiments. The results of the current study indicate that the initial Ca2+ increase in response to bradykinin stimulation is not affected by halothane, but that pulse applications of halothane (0.4-2 mM) or isoflurane (0.5-1 mM) reversibly reduce the sustained cytosolic Ca2+ increase initiated either by bradykinin or by the Ca2+ pump inhibitor thapsigargin. In addition, halothane appeared to dose-dependently inhibit the Ca2+ influx evoked by bradykinin, and to cause, concomitant to a decrease in cytosolic Ca2+ concentration, a depolarization of the cell potential. Halothane failed, however, to affect internal Ca2+ concentration in thapsigargin-treated endothelial cells, which were depolarized using a high K+ external solution. Finally, halothane and isoflurane decreased the open probability of the Ca(2+)-dependent K+ channel present in these cells. These observations suggest that the effects of halothane and isoflurane on Ca2+ homeostasis in BAE cells reflect, for the most part, a reduction of the thapsigargin- or bradykinin-evoked Ca2+ influx, which would be consequent to a cellular depolarization caused by an inhibition of the Ca(2+)-dependent K+ channel activity initiated after cell stimulation.

Development of endothelial nitric oxide synthase in endothelial cells in the human cerebrum

We demonstrate the distribution and development of endothelial nitric oxide synthase (eNOS) immunoreactivity in vessels of the human brain. eNOS-positive endothelial cells were recognized in small vessels in the parenchyma of the cerebrum, as well as in the large arteries and veins in the leptomeninges. By 10–13 weeks of gestation, eNOS-positive endothelial cells had already appeared in the vessels of the leptomeninges and deep white matter. Immunoreactivity for eNOS was noted in most vessels at 14–17 weeks in the intermediate white matter, at 18–21 weeks in the cortex, and at 23–26 weeks in the subcortical white matter. Such differences in regional development may be responsible in part for the topographical predilection for hemorrhagic or hypoxic-ischemic lesions in the developing brain.

Cause or Effect? Enzyme Deficit in Hypertensive Lungs

Nitric oxide, a simple molecule produced from L-arginine by nitric oxide synthase in endothelial cells, has a powerful array of biologic actions. In the pulmonary vasculature, nitric oxide vasodilates vessels, inhibits thrombosis, and limits the proliferation of smooth muscle cells. This study from …