scholarly journals l-Citrulline ameliorates chronic hypoxia-induced pulmonary hypertension in newborn piglets

2009 ◽  
Vol 297 (3) ◽  
pp. L506-L511 ◽  
Author(s):  
Madhumita Ananthakrishnan ◽  
Frederick E. Barr ◽  
Marshall L. Summar ◽  
Heidi A. Smith ◽  
Mark Kaplowitz ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Chronic Hypoxia ◽  
Vascular Endothelial Cells ◽  
No Production ◽  
Nitrate Accumulation ◽  
Newborn Piglets ◽  
Pulmonary Vascular Endothelium ◽  
Isolated Lungs ◽  
Nitrite Nitrate

Newborn piglets develop pulmonary hypertension and have diminished pulmonary vascular nitric oxide (NO) production when exposed to chronic hypoxia. NO is produced by endothelial NO synthase (eNOS) in the pulmonary vascular endothelium using l-arginine as a substrate and producing l-citrulline as a byproduct. l-Citrulline is metabolized to l-arginine by two enzymes that are colocated with eNOS in pulmonary vascular endothelial cells. The purpose of this study was to determine whether oral supplementation with l-citrulline during exposure of newborn piglets to 10 days of chronic hypoxia would prevent the development of pulmonary hypertension and increase pulmonary NO production. A total of 17 hypoxic and 17 normoxic control piglets were studied. Six of the 17 hypoxic piglets were supplemented with oral l-citrulline starting on the first day of hypoxia. l-Citrulline supplementation was provided orally twice a day. After 10 days of hypoxia or normoxia, the animals were anesthetized, hemodynamic measurements were performed, and the lungs were perfused in situ. Pulmonary arterial pressure and pulmonary vascular resistance were significantly lower in hypoxic animals treated with l-citrulline compared with untreated hypoxic animals ( P < 0.001). In vivo exhaled NO production ( P = 0.03) and nitrite/nitrate accumulation in the perfusate of isolated lungs ( P = 0.04) were significantly higher in l-citrulline-treated hypoxic animals compared with untreated hypoxic animals. l-Citrulline supplementation ameliorated the development of pulmonary hypertension and increased NO production in piglets exposed to chronic hypoxia. We speculate that l-citrulline may benefit neonates exposed to prolonged periods of hypoxia from cardiac or pulmonary causes.

l-Arginine increases nitric oxide production in isolated lungs of chronically hypoxic newborn pigs

2000 ◽  
Vol 88 (5) ◽  
pp. 1797-1803 ◽  
Author(s):  
Candice D. Fike ◽  
Mark R. Kaplowitz ◽  
Linda A. Rehorst-Paea ◽  
Leif D. Nelin
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Chronic Hypoxia ◽  
Fixed Time ◽  
No Production ◽  
Arginine Uptake ◽  
Before And After ◽  
Isolated Lungs ◽  
Air Control

Previously, our laboratory found that pulmonary hypertension developed and lung nitric oxide (NO) production was reduced when piglets were exposed to chronic hypoxia (Fike CD, Kaplowitz MR, Thomas CJ, and Nelin LD. Am J Physiol Lung Cell Mol Physiol 274: L517–L526, 1998). The purposes of this study were to determine whetherl-arginine addition augments NO production and to evaluate whether l-arginine uptake is impaired in isolated lungs of chronically hypoxic newborn piglets. Studies were performed by using 1- to 3-day-old piglets raised in room air (control) or 10% O2 (chronic hypoxia) for 10–12 days. Lung NO production was assessed in isolated lungs from both groups by measuring the perfusate accumulation of nitrites and nitrates (collectively termed [Formula: see text]) before and after addition of l-arginine (10−2 M) to the perfusate. The rate of perfusate[Formula: see text] accumulation increased by 220% (from 0.8 ± 0.4 to 2.5 ± 0.5 nmol/min, P < 0.05) after l-arginine addition to chronic hypoxic lungs but remained unchanged (3.2 ± 0.8 before vs. 3.3 ± 0.4 nmol/min afterl-arginine) in control lungs. In the second series of studies, l-arginine uptake was evaluated by measuring the perfusate concentration ofl-[3H]arginine at fixed time intervals. The perfusate concentration ofl-[3H]arginine at each time point was less ( P < 0.05) in control than in chronic hypoxic lungs. Thus l-arginine uptake was impaired and may underlie in part the reduction in lung NO production that occurs when piglets are exposed to 10–12 days of chronic hypoxia. Moreover, these findings in isolated lungs lead to the possibility that l-arginine supplementation might increase in vivo lung NO production in piglets with chronic hypoxia-induced pulmonary hypertension.

scholarly journals Tetrahydrobiopterin oral therapy recouples eNOS and ameliorates chronic hypoxia-induced pulmonary hypertension in newborn pigs

2016 ◽  
Vol 311 (4) ◽  
pp. L743-L753 ◽  
Author(s):  
Anna Dikalova ◽  
Judy L. Aschner ◽  
Mark R. Kaplowitz ◽  
Marshall Summar ◽  
Candice D. Fike
Keyword(s):  
Pulmonary Hypertension ◽  
Chronic Hypoxia ◽  
Disease Onset ◽  
Pulmonary Arteries ◽  
Pulmonary Vasculature ◽  
Hypoxic Exposure ◽  
No Production ◽  
Major Purpose ◽  
Newborn Piglets ◽  
Enos Uncoupling

We previously showed that newborn piglets who develop pulmonary hypertension during exposure to chronic hypoxia have diminished pulmonary vascular nitric oxide (NO) production and evidence of endothelial NO synthase (eNOS) uncoupling (Fike CD, Dikalova A, Kaplowitz MR, Cunningham G, Summar M, Aschner JL. Am J Respir Cell Mol Biol 53: 255–264, 2015). Tetrahydrobiopterin (BH4) is a cofactor that promotes eNOS coupling. Current clinical strategies typically invoke initiating treatment after the diagnosis of pulmonary hypertension, rather than prophylactically. The major purpose of this study was to determine whether starting treatment with an oral BH4 compound, sapropterin dihydrochloride (sapropterin), after the onset of pulmonary hypertension would recouple eNOS in the pulmonary vasculature and ameliorate disease progression in chronically hypoxic piglets. Normoxic (control) and hypoxic piglets were studied. Some hypoxic piglets received oral sapropterin starting on day 3 of hypoxia and continued throughout an additional 7 days of hypoxic exposure. Catheters were placed for hemodynamic measurements, and pulmonary arteries were dissected to assess eNOS dimer-to-monomer ratios (a measure of eNOS coupling), NO production, and superoxide (O2·−) generation. Although higher than in normoxic controls, pulmonary vascular resistance was lower in sapropterin-treated hypoxic piglets than in untreated hypoxic piglets. Consistent with eNOS recoupling, eNOS dimer-to-monomer ratios and NO production were greater and O2·− generation was less in pulmonary arteries from sapropterin-treated than untreated hypoxic animals. When started after disease onset, oral sapropterin treatment inhibits chronic hypoxia-induced pulmonary hypertension at least in part by recoupling eNOS in the pulmonary vasculature of newborn piglets. Rescue treatment with sapropterin may be an effective strategy to inhibit further development of pulmonary hypertension in newborn infants suffering from chronic cardiopulmonary conditions associated with episodes of prolonged hypoxia.

PAF antagonists inhibit pulmonary vascular remodeling induced by hypobaric hypoxia in rats

1992 ◽  
Vol 73 (3) ◽  
pp. 1084-1092 ◽  
Author(s):  
S. Ono ◽  
J. Y. Westcott ◽  
N. F. Voelkel
Keyword(s):  
Pulmonary Hypertension ◽  
Vascular Remodeling ◽  
Chronic Hypoxia ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Hypoxic Exposure ◽  
Pulmonary Vascular Remodeling ◽  
Paf Antagonists ◽  
Isolated Lungs

Chronic hypoxia causes pulmonary hypertension and pulmonary vascular remodeling in rats. Because platelet-activating factor (PAF) levels increase in lung lavage fluid and in plasma from chronically hypoxic rats, we examined the effect of two specific, structurally unrelated PAF antagonists, WEB 2170 and BN 50739, on hypoxia-induced pulmonary vascular remodeling. Treatment with either agent reduced hypoxia-induced pulmonary hypertension and right ventricular hypertrophy at 3 wk of hypoxic exposure (simulated altitude 5,100 m) but did not affect cobalt (CoCl2)-induced pulmonary hypertension. The PAF antagonists had no effect on the hematocrit of normoxic or chronically hypoxic rats or CoCl2-treated rats. Hypoxia-induced pulmonary hypertension was associated with an increase in the vessel wall thickness of the muscular arteries and reduction in the number of peripheral arterioles. In WEB 2170-treated rats, these changes were significantly less severe than those observed in untreated chronically hypoxic rats. PAF receptor blockade had no acute hemodynamic effects; i.e., it did not affect pulmonary arterial pressure or cardiac output nor did it affect the magnitude of acute hypoxic pulmonary vasoconstriction in awake normoxic or chronically hypoxic rats. Isolated lungs from chronically hypoxic rats showed a pressor response to the chemotactic tripeptide N-formyl-Met-Leu-Phe (fMLP) and an increase in the number of leukocytes lavaged from the pulmonary circulation. In vivo treatment with WEB 2170 significantly reduced the fMLP-induced pressor response compared with that observed in isolated lungs from untreated chronically hypoxic rats. These results suggest that PAF contributes to the development of chronic pulmonary hypertension induced by chronic hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic hypoxia decreases nitric oxide production and endothelial nitric oxide synthase in newborn pig lungs

1998 ◽  
Vol 274 (4) ◽  
pp. L517-L526 ◽  
Author(s):  
Candice D. Fike ◽  
Mark R. Kaplowitz ◽  
Carol J. Thomas ◽  
Leif D. Nelin
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Chronic Hypoxia ◽  
No Production ◽  
Newborn Piglets ◽  
Exhaled No ◽  
Isolated Lungs ◽  
Air Control ◽  
Oxide Synthase ◽  
Endothelial Nitric Oxide

To examine the effect of chronic hypoxia on nitric oxide (NO) production and the amount of the endothelial isoform of nitric oxide synthase (eNOS) in lungs of newborn piglets, studies were performed using 1- to 3-day-old piglets raised in room air (control) or 10% O2 (chronic hypoxia) for 10–12 days. Exhaled NO output and plasma nitrites and nitrates (collectively termed[Formula: see text]) were measured in anesthetized animals. [Formula: see text]concentrations were measured in the perfusate of isolated lungs. eNOS amounts were assessed in whole lung homogenates. In the intact piglets, exhaled NO outputs and plasma [Formula: see text]were lower in the chronically hypoxic (exhaled NO output = 0.2 ± 0.1 nmol/min; plasma [Formula: see text] = 10.3 ± 3.7 nmol/ml) than in control animals (exhaled NO output = 0.8 ± 0.2 nmol/min; plasma [Formula: see text] = 22.3 ± 4.3 nmol/ml). In perfused lungs, the perfusate accumulation of [Formula: see text] was lower in chronic hypoxia (1.0 ± 0.3 nmol/min) than in control (2.6 ± 0.6 nmol/min) piglets. The amount of whole lung homogenate eNOS from the chronic hypoxia piglets was 40 ± 8% less than that from the control piglets. The reduced NO production observed in anesthetized animals or perfused lungs of chronically hypoxic newborn piglets is consistent with the finding of reduced lung eNOS protein amounts. Decreased NO production might contribute to the development of chronic hypoxia-induced pulmonary hypertension in newborns.

Exhaled NO is reduced at an early stage of hypoxia-induced pulmonary hypertension in newborn piglets

2003 ◽  
Vol 284 (3) ◽  
pp. L489-L500 ◽  
Author(s):  
Joyce E. Turley ◽  
Leif D. Nelin ◽  
Mark R. Kaplowitz ◽  
Yongmei Zhang ◽  
Candice D. Fike
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Early Stage ◽  
Pulmonary Arteries ◽  
No Production ◽  
Newborn Piglets ◽  
Exhaled No ◽  
Isolated Lungs ◽  
Air Control ◽  
Nos Isoforms

Altered nitric oxide (NO) production could contribute to the pathogenesis of hypoxia-induced pulmonary hypertension. To determine whether parameters of lung NO are altered at an early stage of hypoxia-induced pulmonary hypertension, newborn piglets were exposed to room air (control, n = 21) or 10% O2 (hypoxia, n = 19) for 3–4 days. Some lungs were isolated and perfused for measurement of exhaled NO output and the perfusate accumulation of nitrite and nitrate (NOx−), the stable metabolites of NO. Pulmonary arteries (20–600-μm diameter) and their accompanying airways were dissected from other lungs and incubated for NOx− determination. Abundances of the nitric oxide synthase (NOS) isoforms endothelial NOS and neural NOS were assessed in homogenates of PAs and airways. The perfusate NOx− accumulation was similar, whereas exhaled NO output was lower for isolated lungs of hypoxic, compared with control, piglets. The incubation solution NOx− did not differ between pulmonary arteries (PAs) of the two groups but was lower for airways of hypoxic, compared with control, piglets. Abundances of both eNOS and nNOS proteins were similar for PA homogenates from the two groups of piglets but were increased in airway homogenates of hypoxic compared with controls. The NO pathway is altered in airways, but not in PAs, at an early stage of hypoxia-induced pulmonary hypertension in newborn piglets.

Chronic EDRF inhibition and hypoxia: effects on pulmonary circulation and systemic blood pressure

1993 ◽  
Vol 75 (4) ◽  
pp. 1748-1757 ◽  
Author(s):  
V. Hampl ◽  
S. L. Archer ◽  
D. P. Nelson ◽  
E. K. Weir
Keyword(s):  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Chronic Hypoxia ◽  
Acute Hypoxia ◽  
Systemic Blood Pressure ◽  
Systemic Circulation ◽  
Systemic Arterial Pressure ◽  
Hypoxic Pulmonary Hypertension ◽  
Basal Tone ◽  
Isolated Lungs

It has been suggested that chronic hypoxic pulmonary hypertension results from chronic hypoxic inhibition of endothelium-derived relaxing factor (EDRF) synthesis. We tested this hypothesis by studying whether chronic EDRF inhibition by N omega-nitro-L-arginine methyl ester (L-NAME) would induce pulmonary hypertension similar to that found in chronic hypoxia. L-NAME (1.85 mM) was given for 3 wk in drinking water to rats living in normoxia or hypoxia. Unlike chronic hypoxia, chronic L-NAME treatment did not increase pulmonary arterial pressure. Cardiac output was reduced and mean systemic arterial pressure was increased by chronic L-NAME treatment. The vascular pressure-flow relationship in isolated lungs was shifted toward higher pressures by chronic hypoxia and, to a lesser degree, by L-NAME intake. In isolated lungs, vasoconstriction in response to angiotensin II and acute hypoxia and vasodilation in response to sodium nitroprusside were increased by chronic L-NAME treatment in normoxia and chronic hypoxia. Chronic hypoxia, but not L-NAME, induced hypertensive pulmonary vascular remodeling. Chronic supplementation with the EDRF precursor L-arginine did not have any significant effect on chronic hypoxic pulmonary hypertension. We conclude that the chronic EDRF deficiency state, induced by L-NAME, does not mimic chronic hypoxic pulmonary hypertension in our model. In addition, EDRF proved to be less important for basal tone regulation in the pulmonary than in the systemic circulation.

scholarly journals L‐Citrulline Inhibits Chronic Hypoxia‐Induced Pulmonary Hypertension in Newborn Piglets

2008 ◽  
Vol 22 (S1) ◽  
Author(s):  
Candice Fike ◽  
Madhumita Ananthakrishnan ◽  
Mark Kaplowitz ◽  
Frederick Barr ◽  
Marshall Summar
Keyword(s):  
Pulmonary Hypertension ◽  
Chronic Hypoxia ◽  
Newborn Piglets

Abstract 15303: Dimethylarginine Dimethylaminohydrolase-1 is Not Involved in Chronic Hypoxic Pulmonary Hypertension and Right Ventricular Hypertrophy in Mice

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Juliane Hannemann ◽  
Antonia Glatzel ◽  
Jonas Hillig ◽  
Julia Zummack ◽  
Rainer H Boeger
Keyword(s):  
Pulmonary Hypertension ◽  
Right Ventricular ◽  
Ventricular Hypertrophy ◽  
Chronic Hypoxia ◽  
Right Ventricular Hypertrophy ◽  
Cardiomyocyte Hypertrophy ◽  
No Production ◽  
Knock Out ◽  
Knock Out Mice ◽  
Adma Concentration

Introduction: Chronic hypoxia causes persistent pulmonary vasoconstriction and leads to pulmonary hypertension and right ventricular hypertrophy. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis; its level increases in hypoxia concomitantly with reduced activity of dimethylarginine dimethylaminohydrolases (DDAH-1 and DDAH-2), the enzymes metabolizing ADMA. DDAH knockout models may therefore help to understand the pathophysiological roles of this enzyme and its substrate, ADMA, in the development of hypoxia-associated pulmonary hypertension. Hypothesis: We hypothesized that DDAH1 knock-out mice have an attenuated hypoxia-induced elevation of ADMA and reduced right ventricular hypertrophy. Methods: DDAH1 knock-out mice (KO) and their wild-type littermates (WT) were subjected to normoxia (NX) or hypoxia (HX) during 21 days. We measured ADMA concentration in plasma, DDAH1 and DDAH2 expression in the lung, right ventricular hypertrophy by the Fulton index, cardiomyocyte hypertrophy by dystrophin staining of heart tissues, and muscularization of pulmonary arterioles by CD31 and α-actin staining of lung sections. Results: DDAH1 KO mice had higher ADMA concentration than WT under NX (2.31±0.33 μmol/l vs. 1.20±0.17 μmol/l; p < 0.05). ADMA significantly increased in WT-HX (to 1.74±0.86 μmol/l; p < 0.05 vs. normoxia), whilst it did not further increase in KO-HX (2.58±0.58 μmol/l; p = n.s.). This was paralleled by a 38±13% reduction in DDAH1 mRNA but not DDAH2 mRNA expression, and reduced DDAH protein expression. We observed right ventricular hypertrophy under hypoxia in both, WT and KO mice, with no significant differences between both genotypes. Further, cardiomyocyte hypertrophy and pulmonary arteriolar muscularization were significantly increased by hypoxia, but not significantly different between WT and KO mice. Conclusions: We conclude that chronic hypoxia causes an elevation of ADMA, which impairs NO production and leads to endothelial dysfunction and vasoconstriction. Downregulation of DDAH expression and activity may be involved in this; however, knockout of DDAH1 does not modify the pathophysiological changes in remodeling of the pulmonary vasculature and the right ventricle.

Nitric oxide synthesis by rat pleural mesothelial cells: induction by cytokines and lipopolysaccharide

1993 ◽  
Vol 265 (2) ◽  
pp. L110-L116 ◽  
Author(s):  
M. W. Owens ◽  
M. B. Grisham
Keyword(s):  
Nitric Oxide ◽  
Mononuclear Cells ◽  
Interleukin 1 ◽  
Mesothelial Cells ◽  
No Production ◽  
Nitrate Accumulation ◽  
Pleural Mesothelial Cells ◽  
Nitrate Production ◽  
Close Proximity ◽  
Nitrite Nitrate

The close proximity of pleural mesothelial cells (PMC) and mononuclear cells during pleural inflammation suggests that leukocyte-derived products (e.g., cytokines) may play an important role in modulating PMC function. The purpose of this study was to determine whether certain cytokines and bacterial products induce PMC to produce nitric oxide (NO). Confluent monolayers of rat PMC were exposed to tumor necrosis factor (TNF), interleukin-1 beta (IL-1), gamma-interferon (IFN), or lipopolysaccharide (LPS) individually and in various double and triple combinations for 6–72 h. Concentrations of nitrite and nitrate were quantified and used as indirect indices of NO production. Nitrite/nitrate accumulation was maximal at 72 h, with most of the increase occurring from 48 to 72 h. Maximal nitrite/nitrate production was observed with triple combinations with the combination of LPS, IL-1, and TNF giving the highest concentration (137.4 +/- 2.8 microM). Nitrite/nitrate production was significantly inhibited by NG-nitro-L-arginine methyl ester, suggesting that nitrite and nitrate were derived from the L-arginine-dependent formation of NO. These data indicate that PMC can be induced to produce large amounts of NO in response to specific combinations of proinflammatory cytokines and LPS.

Thapsigargin stimulates increased NO activity in hypoxic hypertensive rat lungs and pulmonary arteries

1996 ◽  
Vol 80 (4) ◽  
pp. 1336-1344 ◽  
Author(s):  
M. Muramatsu ◽  
R. C. Tyler ◽  
D. M. Rodman ◽  
I. F. McMurtry
Keyword(s):  
Pulmonary Artery ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Male Rats ◽  
Pulmonary Vasculature ◽  
No Production ◽  
Low Concentrations ◽  
Pulmonary Vascular Endothelium ◽  
Increased Sensitivity ◽  
Stimulation Of

This study addressed the controversy of whether endothelium-derived nitric oxide (NO) activity is increased or decreased in the hypertensive pulmonary vasculature of chronically hypoxic rats. Thapsigargin, a receptor-independent Ca2+ agonist and stimulator of endothelial NO production, was used to compare NO-mediated vasodilation in perfused lungs and conduit pulmonary artery rings isolated from adult male rats either kept at Denver's altitude of 5,280 ft (control pulmonary normotensive rats) or exposed for 4-5 wk to the simulated altitude of 17,000 ft (chronically hypoxic pulmonary hypertensive rats). Under baseline conditions, thapsigargin (10(-9)-10(-7) M) caused vasodilation in hypertensive lungs and vasoconstriction in normotensive lungs. Whereas the sustained vasodilation in hypertensive lungs was reversed to vasoconstriction by the inhibitor of NO synthase N(omega)-nitro-L-arginine (L-NNA; 10(-4) M), a transient vasodilation to thapsigargin in acutely vasoconstricted normotensive lungs was potentiated. As measured by a chemiluminescence assay, the recirculated perfusate of hypertensive lungs accumulated considerably higher levels of NO-containing compounds that did normotensive lungs, and thapsigargin-induced stimulation of NO-containing compounds accumulation was greater in hypertensive than in normotensive lungs. Similarly, low concentrations of thapsigargin (10(-10)-10(-9) M) caused greater endothelium-dependent L-NNA-reversible relaxation of hypertensive than of normotensive pulmonary artery rings. The increased sensitivity of hypertensive arteries to thapsigargin-induced relaxation was eliminated in nominally Ca(2+)-free medium and was not mimicked by ryanodine, a releaser of intracellular Ca2+. These results with thapsigargin, which acts on endothelial cells to stimulate Ca2+ influx and a sustained rise in intracellular Ca2+ concentration, support the idea that pulmonary vascular endothelium-derived NO activity is increased rather than decreased in chronic hypoxia-induced pulmonary hypertension in rats.

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