The principal pathways involved in thein vivomodulation of hypoxic pulmonary vasoconstriction, pulmonary arterial remodelling and pulmonary hypertension

2016 ◽  
Vol 219 (4) ◽  
pp. 728-756 ◽  
Author(s):  
D. Kylhammar ◽  
G. Rådegran
Keyword(s):  
Pulmonary Hypertension ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

Nitric oxide inhalation: effects on the ovine neonatal pulmonary and systemic circulations

1996 ◽  
Vol 8 (3) ◽  
pp. 431 ◽  
Author(s):  
V DeMarco ◽  
JW Skimming ◽  
TM Ellis ◽  
S Cassin
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Pulmonary Circulation ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Minimum Concentration ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial ◽  
Inhaled No

Others have shown that inhaled nitric oxide causes reversal of pulmonary hypertension in anaesthetized perinatal sheep. The present study examined haemodynamic responses to inhaled NO in the normal and constricted pulmonary circulation of unanaesthetized newborn lambs. Three experiments were conducted on each of 7 lambs. First, to determine a minimum concentration of NO which could reverse acute pulmonary hypertension caused by infusion of the thromboxame mimic U46619, the haemodynamic effects of 5 different doses of inhaled NO were examined. Second, the effects of inhaling 80 ppm NO during hypoxic pulmonary vasoconstriction were examined. Finally, to determine if tachyphalaxis occurs during NO inhalation, lambs were exposed to 80 ppm NO for 3 h during which time pulmonary arterial pressure was doubled by infusion of U46619. Breathing NO (80 ppm) caused a slight but significant decrease in pulmonary vascular resistance (PVR) in lambs with normal pulmonary arterial pressure (PAP). Nitric oxide, inhaled at concentrations between 10 and 80 ppm for 6 min (F1O2 = 0.60), caused decreases in PVR when PAP was elevated with U46619. Nitric oxide acted selectively on the pulmonary circulation, i.e. no changes occurred in systemic arterial pressure or any other measured variable. Breathing 80 ppm NO for 6 min reversed hypoxic pulmonary vasoconstriction. In the chronic exposure study, inhaling 80 ppm NO for 3 h completely reversed U46619-induced pulmonary hypertension. Although arterial methaemoglobin increased during the 3-h exposure to 80 ppm NO, there was no indication that this concentration of NO impairs oxygen loading. These data demonstrate that NO, at concentrations as low as 10 ppm, is a potent, rapid-action, and selective pulmonary vasodilator in unanaesthetized newborn lambs with elevated pulmonary tone. Furthermore, these data support the use of inhaled NO for treatment of infants with pulmonary hypertension.

Garlic prevents hypoxic pulmonary hypertension in rats

1998 ◽  
Vol 275 (2) ◽  
pp. L283-L287 ◽  
Author(s):  
Michael B. Fallon ◽  
Gary A. Abrams ◽  
Tarek T. Abdel-Razek ◽  
Jun Dai ◽  
Shi-Juan Chen ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
High Altitude ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Control Group ◽  
Nitric Oxide Synthase Inhibitor ◽  
Hypoxic Pulmonary Hypertension ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial ◽  
Synthase Inhibitor

Hypoxic pulmonary vasoconstriction underlies the development of high-altitude pulmonary edema. Anecdotal observations suggest a beneficial effect of garlic in preventing high-altitude symptoms. To determine whether garlic influences pulmonary vasoconstriction, we assessed the effect of garlic on pulmonary pressures in rats subjected to alveolar hypoxia and on vasoconstriction in isolated pulmonary arterial rings. Garlic gavage (100 mg/kg body wt) for 5 days resulted in complete inhibition of acute hypoxic pulmonary vasoconstriction compared with the control group. No difference in mean arterial pressure or heart rate response to hypoxia was seen between the groups. Garlic solution resulted in a significant dose-dependent vasorelaxation in both endothelium-intact and mechanically endothelium-disrupted pulmonary arterial rings. The administration of N G-nitro-l-arginine methyl ester (a nitric oxide synthase inhibitor) inhibited the vasodilatory effect of garlic by 80%. These studies document that garlic blocks hypoxic pulmonary hypertension in vivo and demonstrate a combination of endothelium-dependent and -independent mechanisms for the effect in pulmonary arterial rings.

ID: 59: ROLE OF ENDOTHELIAL HYPOXIA–INDUCIBLE FACTORS IN HYPOXIA-INDUCED PULMONARY VASOCONSTRICITON

2016 ◽  
Vol 64 (4) ◽  
pp. 974.2-975
Author(s):  
Y Gu ◽  
H Tang ◽  
JG Garcia ◽  
JX Yuan ◽  
DR Fraidenburg ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Pulmonary Hypertension ◽  
Chronic Hypoxia ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Conditional Knockout ◽  
Induced Response ◽  
Hypoxia Inducible Factors ◽  
Pulmonary Vasoconstriction ◽  
High K ◽  
Pulmonary Arterial

RationalPulmonary arterial hypertension (PAH) is a rare but progressive and fatal disease caused by functional and structural changes in the pulmonary vasculature, which lead to an increase in pulmonary vascular resistance (PVR). Persistent hypoxia causes sustained pulmonary vasoconstriction (HPV) that may contributes to the elevated PVR in patients with pulmonary hypertension associated with hypoxia and lung diseases and in residents living in high altitude areas. Little is known about the molecular and cellular mechanisms, which underlie hypoxic pulmonary vasoconstriction and the development and progression of pulmonary hypertension.Methods and ResultsTo determine the functional relevance of hypoxia and hypoxia-inducible factors (HIFs) in the development of acute HPV, we compared high K+-induced increase in pulmonary arterial pressure (PAP) and acute alveolar hypoxia-mediated increase in PAP in isolated perfused and ventilated lungs between wild type (WT) and HIF1α or HIF2α conditional knockout (KO) mice. Conditional and inducible deletion of HIF1α or HIF2α in endothelial cells (HIF1αEC−/−, or HIF2αEC−/−), but not smooth muscle cells, dramatically protected mice from hypoxia-induced pulmonary hypertension. We analyzed the hypoxia-induced response in isolated lungs from WT and KO mice. Ventilation of lungs from mice with 1% O2 provoked a vasoconstrictor response and reached to the plateau within 4 min in both WT, HIF1αEC−/−, and HIF2αEC−/− mice. Normoxic vascular ton were not affected by deletion of HIF1α or HIF2α and there is no difference of vasoconstriction induced by high K+ between WT and KO mice.ConclusionOur study has demonstrated that deletion of HIF1α or HIF2α in endothelial cells dramatically attenuate chronic hypoxia-induced pulmonary hypertension, but negligibly affect the acute hypoxia-induced pulmonary vasoconstriction. These results implicated that targets of endothelial HIFs signaling pathway may lead to novel therapeutic targets for chronic hypoxia-induced pulmonary hypertension but endothelial HIFs signaling are not involved in acute hypoxic pulmonary vasoconstriction.

Role of leukotriene C4 in pulmonary hypertension: platelet-activating factor vs. hypoxia

1990 ◽  
Vol 68 (4) ◽  
pp. 1628-1633 ◽  
Author(s):  
D. Davidson ◽  
M. Singh ◽  
G. F. Wallace
Keyword(s):  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Pulmonary Arterial Pressure ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Platelet Activating Factor ◽  
Lung Parenchyma ◽  
Base Line ◽  
Leukotriene C4 ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

The aim of this study was to determine whether leukotriene C4 (LTC4) is a mediator of hypoxic pulmonary vasoconstriction. We hypothesized that similar increases in LTC4, detected in the lung parenchyma and pulmonary vascular compartment during cyclooxygenase blockade with indomethacin (INDO), would be observed during an equal increase in pulmonary arterial pressure caused by acute alveolar hypoxia (HYP, 100% N2) or platelet-activating factor (PAF, 10 micrograms into the pulmonary artery). Rat lungs were perfused at constant flow in vitro with an albumin-Krebs-Henseleit solution. Mean pulmonary arterial pressure (n = 6 per group) increased from a base line of 10.9 +/- 1.2 to 15.8 +/- 2.1 (HYP + INDO) and 15.5 +/- 1.9 (SE) Torr (PAF + INDO). LTC4 levels increased only in response to PAF + INDO; perfusate levels increased from 0.4 +/- 0.07 to 5.3 +/- 1.1 ng/40 ml, and lung parenchymal levels increased from 1.9 +/- 0.07 to 22.8 +/- 5.3 ng/lung. Diethylcarbamazine (lipoxygenase inhibitor) reduced PAF-induced lung parenchymal levels of LTC4 by 68% and pulmonary hypertension by 63%. We conclude that 1) LTC4 is not a mediator of hypoxic pulmonary vasoconstriction and 2) intravascular PAF is a potent stimulus for LTC4 production in the lung parenchyma.

Hypoxic Pulmonary Vasoconstriction and Chronic Lung Disease

2013 ◽  
Vol 12 (3) ◽  
pp. 135-144 ◽  
Author(s):  
Erik R. Swenson
Keyword(s):  
Pulmonary Hypertension ◽  
Lung Disease ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
World Health ◽  
Disease States ◽  
Pulmonary Vasoconstriction ◽  
Local Ventilation ◽  
Pulmonary Vascular Endothelium ◽  
Health And Disease ◽  
Health Organization

Hypoxic vasoconstriction in the lung is a unique and fundamental characteristic of the pulmonary circulation. It functions in health and disease states to better preserve ventilation-perfusion matching by diverting blood flow to better ventilated regions when local ventilation is compromised. As more areas of lung become hypoxic either with high altitude or global lung disease, then hypoxic pulmonary vasoconstriction (HPV) becomes less effective in ventilation-perfusion matching and can lead to pulmonary hypertension. HPV is intrinsic to the vascular smooth muscle and its mechanisms remain poorly understood. In addition, the pulmonary vascular endothelium, red cells, lung innervation, and numerous circulating vasoactive agents also affect the strength of HPV. This review will discuss the pathophysiology of HPV and address its role in pulmonary hypertension associated with World Health Organization Group 3 diseases. When sustained beyond many hours, HPV may initiate pulmonary vascular remodeling and lead to more fixed and less oxygen-responsive pulmonary hypertension if the hypoxic stimulus is maintained.

Inhibition of hypoxic pulmonary vasoconstriction by antagonists of store-operated Ca2+ and nonselective cation channels

2005 ◽  
Vol 289 (1) ◽  
pp. L5-L13 ◽  
Author(s):  
Letitia Weigand ◽  
Joshua Foxson ◽  
Jian Wang ◽  
Larissa A. Shimoda ◽  
J. T. Sylvester
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Acute Hypoxia ◽  
Pulmonary Arteries ◽  
Cation Channels ◽  
Pulmonary Vasoconstriction ◽  
Nonselective Cation Channels ◽  
Pressor Responses ◽  
Intracellular Ca ◽  
Pulmonary Arterial

Previous studies indicated that acute hypoxia increased intracellular Ca2+ concentration ([Ca2+]i), Ca2+ influx, and capacitative Ca2+ entry (CCE) through store-operated Ca2+ channels (SOCC) in smooth muscle cells from distal pulmonary arteries (PASMC), which are thought to be a major locus of hypoxic pulmonary vasoconstriction (HPV). Moreover, these effects were blocked by Ca2+-free conditions and antagonists of SOCC and nonselective cation channels (NSCC). To test the hypothesis that in vivo HPV requires CCE, we measured the effects of SOCC/NSCC antagonists (SKF-96365, NiCl2, and LaCl3) on pulmonary arterial pressor responses to 2% O2 and high-KCl concentrations in isolated rat lungs. At concentrations that blocked CCE and [Ca2+]i responses to hypoxia in PASMC, SKF-96365 and NiCl2 prevented and reversed HPV but did not alter pressor responses to KCl. At 10 μM, LaCl3 had similar effects, but higher concentrations (30 and 100 μM) caused vasoconstriction during normoxia and potentiated HPV, indicating actions other than SOCC blockade. Ca2+-free perfusate and the voltage-operated Ca2+ channel (VOCC) antagonist nifedipine were potent inhibitors of pressor responses to both hypoxia and KCl. We conclude that HPV required influx of Ca2+ through both SOCC and VOCC. This dual requirement and virtual abolition of HPV by either SOCC or VOCC antagonists suggests that neither channel provided enough Ca2+ on its own to trigger PASMC contraction and/or that during hypoxia, SOCC-dependent depolarization caused secondary activation of VOCC.

Endothelium-derived relaxing factor activity in rat lung during hypoxic pulmonary vascular remodeling

1993 ◽  
Vol 74 (3) ◽  
pp. 1061-1065 ◽  
Author(s):  
L. Zhao ◽  
D. E. Crawley ◽  
J. M. Hughes ◽  
T. W. Evans ◽  
R. J. Winter
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Hypoxic Exposure ◽  
Control Group ◽  
Pulmonary Vascular Remodeling ◽  
Relaxing Factor ◽  
Pulmonary Vasoconstriction ◽  
O2 Concentration ◽  
Pulmonary Arterial ◽  
Endothelium Derived Relaxing Factor

We have investigated the role of endothelium-derived relaxing factor in modulating hypoxic pulmonary vasoconstriction by inhibiting its synthesis with the false substrate NG-monomethyl-L-arginine (L-NMMA) in the isolated blood-perfused lungs of Wistar rats after chronic hypoxia (CH, fractional inspiratory O2 concentration 10%) for 15 h, 2 days, and 7 days. Lungs were perfused with blood of normal hematocrit at constant flow (18 ml/min) ventilated with 1) 95% air-5% CO2 (normoxia) and 2) 2% O2–5% CO2-93% N2 (hypoxia) and were studied in the absence and presence of L-NMMA (30 and 300 microM) or L-arginine (L-Arg, 1 and 6 mM) in separate groups. Pulmonary arterial pressure (Ppa) rose incrementally with hypoxic exposure (all P < 0.05 vs. normoxic control group). Hypoxic pulmonary vasoconstriction (HPV) was markedly reduced after 15 h and 2 days of CH: the mean increases in Ppa (delta Ppa) in hypoxia were 15.3, 3.5, 3.8, and 13.6 mmHg in control rats and rats exposed to 15 h (P < 0.05 vs. control and 7 days of CH), 2 days (P < 0.001 vs. control and 7 days of CH), and 7 days of CH, respectively. Ppa in control rats and rats exposed to 15 h, 2 days, and 7 days of CH were 137, 179, 184, and 166% of control, respectively, after 30 microM L-NMMA (all P < 0.05 when expressed as percent change vs. no L-NMMA). Similar augmentation in HPV was seen after 30 microM L-NMMA, with all hypoxic groups having a greater response than control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Intra - Pulmonary Arterial Diltiazem on Hypoxic Pulmonary Vasoconstriction in Dogs

1992 ◽  
Vol 25 (3) ◽  
pp. 468
Author(s):  
Seong Deok Kim ◽  
Chong Sung Kim ◽  
Hee Soo Kim ◽  
Seung Woon Lim
Keyword(s):  
Hypoxic Pulmonary Vasoconstriction ◽  
Pulmonary Vasoconstriction ◽  
Pulmonary Arterial

PEEP inhibits hypoxic pulmonary vasoconstriction in dogs

1991 ◽  
Vol 70 (4) ◽  
pp. 1867-1873 ◽  
Author(s):  
P. Lejeune ◽  
J. L. Vachiery ◽  
J. M. De Smet ◽  
M. Leeman ◽  
S. Brimioulle ◽  
...  
Keyword(s):  
Inferior Vena ◽  
Intact Animal ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Balloon Catheter ◽  
Vena Cava ◽  
Pulmonary Hemodynamics ◽  
Mean Pulmonary Arterial Pressure ◽  
Pulmonary Vasoconstriction ◽  
Anesthetized Dogs ◽  
Pulmonary Arterial

The effects of an increase in alveolar pressure on hypoxic pulmonary vasoconstriction (HPV) have been reported variably. We therefore studied the effects of positive end-expiratory pressure (PEEP) on pulmonary hemodynamics in 13 pentobarbital-anesthetized dogs ventilated alternately in hyperoxia [inspired O2 fraction (FIO2) 0.4] and in hypoxia (FIO2 0.1). In this intact animal model, HPV was defined as the gradient between hypoxic and hyperoxic transmural (tm) mean pulmonary arterial pressure [Ppa(tm)] at any level of cardiac index (Q). Ppa(tm)/Q plots were constructed with mean transmural left atrial pressure [Pla(tm)] kept constant at approximately 6 mmHg (n = 5 dogs), and Ppa(tm)/PEEP plots were constructed with Q kept constant approximately 2.8 l.min-1.m-2 and Pla(tm) kept constant approximately 8 mmHg (n = 8 dogs). Q was manipulated using a femoral arteriovenous bypass and a balloon catheter in the inferior vena cava. Pla(tm) was held constant by a balloon catheter placed by left thoracotomy in the left atrium. Increasing PEEP, from 0 to 12 Torr by 2-Torr increments, at constant Q and Pla(tm), increased Ppa(tm) from 14 +/- 1 (SE) to 19 +/- 1 mmHg in hyperoxia but did not affect Ppa(tm) (from 22 +/- 2 to 23 +/- 1 mmHg) in hypoxia. Both hypoxia and PEEP, at constant Pla(tm), increased Ppa(tm) over the whole range of Q studied, from 1 to 5 l/min, but more at the highest than at the lowest Q and without change in extrapolated pressure intercepts. Adding PEEP to hypoxia did not affect Ppa(tm) at all levels of Q.(ABSTRACT TRUNCATED AT 250 WORDS)

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