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.

Hypoxia inhibits increased ETB receptor-mediated NO synthesis in hypertensive rat lungs

1999 ◽  
Vol 276 (4) ◽  
pp. L571-L581 ◽  
Author(s):  
Koichi Sato ◽  
David M. Rodman ◽  
Ivan F. McMurtry
Keyword(s):  
Pulmonary Arteries ◽  
Male Rats ◽  
Hypoxic Exposure ◽  
No Production ◽  
Type B ◽  
Hypertensive Rat ◽  
Rat Lungs ◽  
Intracellular Ca ◽  
Etb Receptor ◽  
Stimulation Of

Although hypertensive lungs of chronically hypoxic rats express increased levels of nitric oxide (NO) synthases (NOSs) and produce increased amounts of NO-containing compounds (NOx) during normoxic ventilation, the level of NO production during hypoxic exposure is unclear. Because hypoxia inhibits NO synthesis in normotensive lungs, we investigated whether hypoxic ventilation inhibited NO synthesis in isolated hypertensive lungs and chronically hypoxic rats. Measurement of perfusate NOx concentration in hypertensive lungs from male rats exposed to 4 wk of hypobaric hypoxia showed that basal NOx production was reduced during hypoxic (0% O2) vs. normoxic (21% O2) ventilation. Similarly, plasma NOxconcentration was lower in chronically hypoxic rats breathing 10% O2 than in those breathing 21% O2. Hypoxic inhibition of lung NOx production was not prevented by supplementaryl-arginine or tetrahydrobiopterin and was not mimicked by inhibition of Ca2+ influx. However, it was mimicked by inhibition of constitutive NOS with N G-monomethyl-l-arginine and chelation of intracellular Ca2+. The endothelin type B-receptor antagonist BQ-788 prevented the increases in NOx production associated with normoxic ventilation in both isolated hypertensive lungs and intact chronically hypoxic rats. These results suggest that a reduced supply of the cosubstrate molecular O2 to NOS counteracts an endothelin type B receptor-mediated stimulation of NO synthesis in hypertensive rat lungs. Thus, despite increased NOS protein in the lungs and pulmonary arteries of chronically hypoxic rats, direct hypoxic inhibition of NO production may contribute to the development of 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.

Sex Differences in Right Ventricular-Vascular Coupling and Pulmonary Artery Impedance in Response to Chronic Hypoxia and Recovery

2012 ◽  
Author(s):  
Aiping Liu ◽  
Lian Tian ◽  
Diana M. Tabima ◽  
Naomi C. Chesler
Keyword(s):  
Pulmonary Artery ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Pulmonary Artery Hypertension ◽  
Vascular Impedance ◽  
Female Predominance ◽  
Collagen Accumulation ◽  
Dominant Disease ◽  
Pulmonary Arterial

Pulmonary artery hypertension (PAH) is a female dominant disease (the female-to-male ratio is 4:1), characterized by small distal pulmonary arterial narrowing and large proximal arterial stiffening, which increase right ventricle (RV) afterload and ultimately lead to RV failure [1,2]. Our recent studies have shown that collagen accumulation induced by chronic hypoxia increases the stiffness of the large extralobar pulmonary arteries (PAs) [3], and affects pulmonary vascular impedance (PVZ) [4]. The role of collagen in the female predominance in developing PAH has not been explored to date.

scholarly journals Regulation of soluble guanylyl cyclase-α1 expression in chronic hypoxia-induced pulmonary hypertension: role of NFATc3 and HuR

2009 ◽  
Vol 297 (3) ◽  
pp. L475-L486 ◽  
Author(s):  
Sergio de Frutos ◽  
Carlos H. Nitta ◽  
Elizabeth Caldwell ◽  
Jessica Friedman ◽  
Laura V. González Bosc
Keyword(s):  
Pulmonary Hypertension ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Guanylyl Cyclase ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Soluble Guanylyl Cyclase ◽  
Muscle Cells ◽  
Pulmonary Artery Smooth Muscle

The nitric oxide/soluble guanylyl cyclase (sGC) signal transduction pathway plays an important role in smooth muscle relaxation and phenotypic regulation. However, the transcriptional regulation of sGC gene expression is largely unknown. It has been shown that sGC expression increases in pulmonary arteries from chronic hypoxia-induced pulmonary hypertensive animals. Since the transcription factor NFATc3 is required for the upregulation of the smooth muscle hypertrophic/differentiation marker α-actin in pulmonary artery smooth muscle cells from chronically hypoxic mice, we hypothesized that NFATc3 is required for the regulation of sGC-α1 expression during chronic hypoxia. Exposure to chronic hypoxia for 2 days induced a decrease in sGC-α1 expression in mouse pulmonary arteries. This reduction was independent of NFATc3 but mediated by nuclear accumulation of the mRNA-stabilizing protein human antigen R (HuR). Consistent with our hypothesis, chronic hypoxia (21 days) upregulated pulmonary artery sGC-α1 expression, bringing it back to the level of the normoxic controls. This response was prevented in NFATc3 knockout and cyclosporin (calcineurin/NFATc inhibitor)-treated mice. Furthermore, we identified effective binding sites for NFATc in the mouse sGC-α1 promoter. Activation of NFATc3 increased sGC-α1 promoter activity in human embryonic derived kidney cells, rat aortic-derived smooth muscle cells, and human pulmonary artery smooth muscle cells. Our results suggest that NFATc3 and HuR are important regulators of sGC-α1 expression in pulmonary vascular smooth muscle cells during chronic hypoxia-induced pulmonary hypertension.

Impaired NO signaling in small pulmonary arteries of chronically hypoxic newborn piglets

2004 ◽  
Vol 286 (6) ◽  
pp. L1244-L1254 ◽  
Author(s):  
Candice D. Fike ◽  
Judy L. Aschner ◽  
Yongmei Zhang ◽  
Mark R. Kaplowitz
Keyword(s):  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Exposure Period ◽  
No Production ◽  
Resistance Level ◽  
Caveolin 1 ◽  
Selective Antagonist ◽  
Newborn Piglets ◽  
No Signaling ◽  
Nos Isoforms

We performed studies to determine whether chronic hypoxia impairs nitric oxide (NO) signaling in resistance level pulmonary arteries (PAs) of newborn piglets. Piglets were maintained in room air (control) or hypoxia (11% O2) for either 3 (shorter exposure) or 10 (longer exposure) days. Responses of PAs to a nonselective NO synthase (NOS) antagonist, Nω-nitro-l-arginine methylester (l-NAME), a NOS-2-selective antagonist, aminoguanidine, and 7-nitroindazole, a NOS-1-selective antagonist, were measured. Levels of NOS isoforms and of two proteins involved in NOS signaling, heat shock protein (HSP) 90 and caveolin-1, were assessed in PA homogenates. PAs from all groups constricted to l-NAME but not to aminoguanidine or 7-nitroindazole. The magnitude of constriction to l-NAME was similar for PAs from control and hypoxic piglets of the shorter exposure period but was diminished for PAs from hypoxic compared with control piglets of the longer exposure period. NOS-3, HSP90, and caveolin-1 levels were similar in hypoxic and control PAs. These findings indicate that NOS-3, but not-NOS 2 or NOS-1, is involved with basal NO production in PAs from both control and hypoxic piglets. After 10 days of hypoxia, NO function is impaired in PAs despite preserved levels of NOS-3, HSP90, and caveolin-1. The development of NOS-3 dysfunction in resistance level PAs may contribute to the progression of chronic hypoxia-induced pulmonary hypertension in newborn piglets.

Chronic hypoxia induces Rho kinase-dependent myogenic tone in small pulmonary arteries

2008 ◽  
Vol 294 (4) ◽  
pp. L797-L806 ◽  
Author(s):  
Brad R. S. Broughton ◽  
Benjimen R. Walker ◽  
Thomas C. Resta
Keyword(s):  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Rho Kinase ◽  
Intraluminal Pressure ◽  
Pulmonary Vasculature ◽  
Myogenic Tone ◽  
Rhoa Activity ◽  
Basal Tone ◽  
Intracellular Ca ◽  
Inner Diameter

Myogenic tone in the pulmonary vasculature of normoxic adult animals is minimal or nonexistent. Whereas chronic hypoxia (CH) increases basal tone in pulmonary arteries, it is unclear if a portion of this elevated tone is due to development of myogenicity. Since basal arterial RhoA activity and Rho kinase (ROK) expression are augmented by CH, we hypothesized that CH elicits myogenic reactivity in pulmonary arteries through ROK-dependent vascular smooth muscle (VSM) Ca2+ sensitization. To test this hypothesis, we assessed the contribution of ROK to basal tone and pressure-induced vasoconstriction in endothelium-disrupted pulmonary arteries [50–300 μm inner diameter (ID)] from control and CH [4 wk at 0.5 atmosphere (atm)] rats. Arteries were loaded with fura-2 AM to continuously monitor VSM intracellular Ca2+ concentration ([Ca2+]i). Basal VSM [Ca2+]i was not different between groups. The ROK inhibitor, HA-1077 (100 nM to 30 μM), caused a concentration-dependent reduction of basal tone in CH arteries but had no effect in control vessels. In contrast, PKC inhibition with GF109203X (1 μM) did not alter basal tone. Furthermore, significant vasoconstriction in response to stepwise increases in intraluminal pressure (5–45 mmHg) was observed at 12, 15, 25, and 35 mmHg in arteries (50–200 μm ID) from CH rats. This myogenic reactivity was abolished by HA-1077 (10 μM) but not by GF109203X. VSM [Ca2+]i was unaltered by HA-1077, GF109203X, or increases in pressure in either group. Myogenicity was not observed in larger vessels (200–300 μm ID). We conclude that CH induces myogenic tone in small pulmonary arteries through ROK-dependent myofilament Ca2+ sensitization.

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.

Chronic hypoxia inhibits Kv channel gene expression in rat distal pulmonary artery

2005 ◽  
Vol 288 (6) ◽  
pp. L1049-L1058 ◽  
Author(s):  
Jian Wang ◽  
Letitia Weigand ◽  
Wenqian Wang ◽  
J. T. Sylvester ◽  
Larissa A. Shimoda
Keyword(s):  
Gene Expression ◽  
Pulmonary Artery ◽  
Chronic Hypoxia ◽  
Pulmonary Arteries ◽  
Mrna Levels ◽  
Protein Levels ◽  
Kv Channel ◽  
Channel Gene ◽  
Pulmonary Arterial ◽  
Α Subunits

In pulmonary arterial smooth muscle cells (PASMCs), voltage-gated K+ (Kv) channels play an important role in regulating membrane potential, cytoplasmic free Ca2+ concentration, and pulmonary vasomotor tone. Previous studies demonstrated that exposure of rats to chronic hypoxia decreased Kv channel function in PASMCs from distal pulmonary arteries (dPA). To determine whether this decrease in function was due to decreased expression of Kv channel proteins and which Kv proteins might be involved, we analyzed Kv channel gene expression in intact, endothelium-denuded dPAs obtained from rats exposed to 10% O2 for 3 wk. Kv1.1, Kv1.2, Kv1.4, Kv1.5, Kv1.6, Kv2.1, Kv3.1, Kv4.3, and Kv9.3 channel α-subunits and Kv1, Kv2, and Kv3 β-subunits were expressed in rat dPAs. Exposure to chronic hypoxia decreased mRNA and protein levels of Kv1.1, Kv1.5, Kv1.6, Kv2.1, and Kv4.3 α-subunits in dPAs but did not alter gene or protein expression of these channels in aorta. Furthermore, chronic hypoxia did not alter the mRNA levels of β-subunits in dPAs. These results suggest that diminished transcription of Kv α-subunits may reduce the number of functional Kv channels in dPAs during prolonged hypoxia, causing the decreased Kv current previously observed in PASMCs and leading to pulmonary artery vasoconstriction.

Stimulation of proteoglycans by IGF I and II in microvessel and large vessel endothelial cells

1987 ◽  
Vol 253 (1) ◽  
pp. E21-E27
Author(s):  
R. S. Bar ◽  
B. L. Dake ◽  
S. Stueck
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Artery ◽  
Vascular Endothelial Cells ◽  
Pulmonary Arteries ◽  
Large Vessel ◽  
Dependent Manner ◽  
Disease States ◽  
Igf I ◽  
Stimulation Of

Endothelial cells were cultured from bovine capillaries and pulmonary arteries, and the effect of insulinlike growth factor (IGF) I and II (multiplication-stimulating activity) and insulin on the synthesis of proteoglycans was determined. IGF I and II stimulated 35SO4 incorporation into proteoglycans in a dose-dependent manner in both microvessel and pulmonary artery endothelial cells with maximum threefold increases. In pulmonary artery cells, the IGFs caused a general stimulation of all classes of glycosaminoglycan-containing proteoglycans. In microvessel endothelial cells, the IGFs appeared to preferentially increase heparan sulfate-containing proteoglycans. Insulin, at concentrations up to 10(-6) M, had no effect on the synthesis of proteoglycans in either microvessel or pulmonary arterial endothelial cells. Thus, the IGFs stimulate the synthesis of proteoglycans in both microvessel and large vessel endothelial cells, a property that is not mimicked by insulin. Because vascular endothelial cells are bathed by IGFs in vivo, such IGF-mediated functions are likely to be significant in both the normal physiology of vascular endothelium and in disease states such as diabetes mellitus.

Endogenous Hydrogen Sulfide Regulates Pulmonary Artery Collagen Remodeling in Rats with High Pulmonary Blood Flow

2009 ◽  
Vol 234 (5) ◽  
pp. 504-512 ◽  
Author(s):  
Xiaohui Li ◽  
Hongfang Jin ◽  
Geng Bin ◽  
Li Wang ◽  
Chaoshu Tang ◽  
...  
Keyword(s):  
Blood Flow ◽  
Hydrogen Sulfide ◽  
Pulmonary Artery ◽  
Lung Tissue ◽  
Pulmonary Blood Flow ◽  
Pulmonary Arteries ◽  
Tissue Growth ◽  
Pulmonary Vasculature ◽  
Collagen Remodeling ◽  
Collagen Iii

The mechanisms responsible for the structural remodeling of pulmonary vasculature induced by increased pulmonary blood flow are not fully understood. This study explores the effect of endogenous hydrogen sulfide (H2S), a novel gasotransmitter, on collagen remodeling of the pulmonary artery in rats with high pulmonary blood flow. Thirty-two Sprague-Dawley rats were randomly divided into sham, shunt, sham+PPG (D,L-propargylglycine, an inhibitor of cystathionine-γ-lyase), and shunt+PPG groups. After 4 weeks of shunting, the relative medial thickness (RMT) of pulmonary arteries and H2S concentration in lung tissues were investigated. Collagen I and collagen III were evaluated by hydroxyproline assay, sirius-red staining, and immunohistochemistry. Pulmonary artery matrix metalloproteinase-13 (MMP-13), tissue inhibitor of metalloproteinase-1 (TIMP-1), and connective tissue growth factor (CTGF) were evaluated by immunohistochemistry. After 4 weeks of aortocaval shunting, resulting in an elevation of lung tissue H2S to 116.4%, rats exhibited collagen remodeling and increased CTGF expression in the pulmonary arteries. Compared with those of the shunt group, lung tissue H2S production was lowered by 23.4%, RMT of the pulmonary artery further increased by 39.5%, pulmonary artery collagen accumulation became obvious, and pulmonary artery CTGF expression elevated ( P < 0.01) in the shunted rats treated with PPG. However, pulmonary artery MMP-13 and TIMP-1 expressions decreased significantly in rats of shunt+PPG group ( P < 0.01). This study suggests that endogenous H2S exerts an important regulatory effect on pulmonary collagen remodeling induced by high pulmonary blood flow.

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