scholarly journals Endothelial alterations during inhaled NO in lambs with pulmonary hypertension: implications for rebound hypertension

2005 ◽  
Vol 288 (1) ◽  
pp. L27-L35 ◽  
Author(s):  
Gregory A. Ross ◽  
Peter Oishi ◽  
Anthony Azakie ◽  
Sohrab Fratz ◽  
Robert K. Fitzgerald ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Soluble Guanylate Cyclase ◽  
Pulmonary Vasculature ◽  
Protein Levels ◽  
Endothelial Response ◽  
Endogenous Nitric Oxide ◽  
Acute Increase ◽  
Clinically Significant ◽  
Inhaled No

Clinically significant increases in pulmonary vascular resistance (PVR) have been noted upon acute withdrawal of inhaled nitric oxide (iNO). Previous studies in the normal pulmonary circulation demonstrate that iNO increases endothelin-1 (ET-1) levels and decreases endogenous nitric oxide synthase (NOS) activity, implicating an endothelial etiology for the increase in resistance upon iNO withdrawal. However, the effect of iNO on endogenous endothelial function in the clinically relevant pulmonary hypertensive circulation is unknown. The objective of this study was to determine the effects of iNO on endogenous NO-cGMP and ET-1 signaling in lambs with preexisting pulmonary hypertension secondary to increased pulmonary blood flow. Eight fetal lambs underwent in utero placement of an aortopulmonary vascular graft (shunt lambs). After delivery (4 wk), the shunt lambs were mechanically ventilated with iNO (40 ppm) for 24 h. After 24 h of inhaled NO, plasma ET-1 levels increased by 34.8% independently of changes in protein levels ( P < 0.05). Contrary to findings in normal lambs, total NOS activity did not decrease during iNO. In fact, Western blot analysis demonstrated that tissue endothelial NOS protein levels decreased by 43% such that NOS activity relative to protein levels actually increased during iNO ( P < 0.05). In addition, the β-subunit of soluble guanylate cyclase decreased by 70%, whereas phosphodiesterase 5 levels were unchanged ( P < 0.05). Withdrawal of iNO was associated with an acute increase in PVR, which exceeded baseline PVR by 45%, and a decrease in cGMP concentrations to levels that were below baseline. These data suggest that the endothelial response to iNO and the potential mechanisms of rebound pulmonary hypertension are dependent upon the underlying pulmonary vasculature.

Regulation of the endogenous NO pathway by prolonged inhaled NO in rats

1998 ◽  
Vol 85 (3) ◽  
pp. 1070-1078 ◽  
Author(s):  
Deborah U. Frank ◽  
Damian J. Horstman ◽  
Geoffrey N. Morris ◽  
Roger A. Johns ◽  
George F. Rich
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Guanylate Cyclase ◽  
Soluble Guanylate Cyclase ◽  
Protein Levels ◽  
Cgmp Pathway ◽  
Isolated Lungs ◽  
Oxide Synthase ◽  
Inhaled No ◽  
Enos Protein

Nitric oxide (NO) modulates the endogenous NO-cGMP pathway. We determined whether prolonged inhaled NO downregulates the NO-cGMP pathway, which may explain clinically observed rebound pulmonary hypertension. Rats were placed in a normoxic (N; 21% O2) or hypoxic (H; 10% O2) environment with and without inhaled NO (20 parts/million) for 1 or 3 wk. Subsequently, nitric oxide synthase (NOS) and soluble guanylate cyclase (GC) activity and endothelial NOS (eNOS) protein levels were measured. Perfusate cGMP levels and endothelium-dependent and -independent vasodilation were determined in isolated lungs. eNOS protein levels and NOS activity were not altered by inhaled NO in N or H rats. GC activity was decreased by 60 ± 10 and 55 ± 11% in N and H rats, respectively, after 1 wk of inhaled NO but was not affected after 3 wk. Inhaled NO had no effect on perfusate cGMP in N lungs. Inhaled NO attenuated the increase in cGMP levels caused by 3 wk of H by 57 ± 11%, but there was no rebound in cGMP after 24 h of recovery. Endothelium-dependent vasodilation was not altered, and endothelium-independent vasodilation was not altered (N) or slightly increased (H, 10 ± 3%) by prolonged inhaled NO. In conclusion, inhaled NO did not alter the endogenous NO-cGMP pathway as determined by eNOS protein levels, NOS activity, or endothelium-dependent vasodilation under N and H conditions. GC activity was decreased after 1 wk; however, GC activity was not altered by 3 wk of inhaled NO and endothelium-independent vasodilation was not decreased.

Inhaled nitric oxide-induced rebound pulmonary hypertension: role for endothelin-1

2001 ◽  
Vol 280 (2) ◽  
pp. H777-H785 ◽  
Author(s):  
D. Michael McMullan ◽  
Janine M. Bekker ◽  
Michael J. Johengen ◽  
Karen Hendricks-Munoz ◽  
Rene Gerrets ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Inhaled Nitric Oxide ◽  
Protein Levels ◽  
Acute Withdrawal ◽  
Clinically Significant ◽  
Inhaled No

Clinically significant increases in pulmonary vascular resistance have been noted on acute withdrawal of inhaled nitric oxide (NO). Endothelin (ET)-1 is a vasoactive peptide produced by the vascular endothelium that may participate in the pathophysiology of pulmonary hypertension. The objectives of this study were to determine the effects of inhaled NO on endogenous ET-1 production in vivo in the intact lamb and to determine the potential role of ET-1 in the rebound pulmonary hypertension associated with the withdrawal of inhaled NO. Seven 1-mo-old vehicle-treated control lambs and six PD-156707 (an ETA receptor antagonist)-treated lambs were mechanically ventilated. Inhaled NO (40 parts per million) was administered for 24 h and then acutely withdrawn. After 24 h of inhaled NO, plasma ET-1 levels increased by 119.5 ± 42.2% ( P < 0.05). Western blot analysis revealed that protein levels of preproET-1, endothelin-converting enzyme-1α, and ETA and ETB receptors were unchanged. On acute withdrawal of NO, pulmonary vascular resistance (PVR) increased by 77.8% ( P < 0.05) in control lambs but was unchanged (−5.5%) in PD-156707-treated lambs. Inhaled NO increased plasma ET-1 concentrations but not gene expression in the intact lamb, and ETA receptor blockade prevented the increase in PVR after NO withdrawal. These data suggest a role for ET-1 in the rebound pulmonary hypertension noted on acute withdrawal of inhaled NO.

Inhaled nitric oxide inhibits NOS activity in lambs: potential mechanism for rebound pulmonary hypertension

1999 ◽  
Vol 277 (5) ◽  
pp. H1849-H1856 ◽  
Author(s):  
Stephen M. Black ◽  
R. Scott Heidersbach ◽  
D. Michael McMullan ◽  
Janine M. Bekker ◽  
Michael J. Johengen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Pulmonary Vascular Resistance ◽  
Vascular Resistance ◽  
Inhaled Nitric Oxide ◽  
Protein Levels ◽  
Acute Withdrawal ◽  
Inhaled No

Life-threatening increases in pulmonary vascular resistance have been noted on acute withdrawal of inhaled nitric oxide (NO), although the mechanisms remain unknown. In vitro data suggest that exogenous NO exposure inhibits endothelial NO synthase (NOS) activity. Thus the objectives of this study were to determine the effects of inhaled NO therapy and its acute withdrawal on endogenous NOS activity and gene expression in vivo in the intact lamb. Six 1-mo-old lambs were mechanically ventilated and instrumented to measure vascular pressures and left pulmonary blood flow. Inhaled NO (40 ppm) acutely decreased left pulmonary vascular resistance by 27.5 ± 4.7% ( P < 0.05). This was associated with a 207% increase in plasma cGMP concentrations ( P < 0.05). After 6 h of inhaled NO, NOS activity was reduced to 44.3 ± 5.9% of pre-NO values ( P < 0.05). After acute withdrawal of NO, pulmonary vascular resistance increased by 52.1 ± 11.6% ( P < 0.05) and cGMP concentrations decreased. Both returned to pre-NO values within 60 min. One hour after NO withdrawal, NOS activity increased by 48.4 ± 19.1% to 70% of pre-NO values ( P < 0.05). Western blot analysis revealed that endothelial NOS protein levels remained unchanged throughout the study period. These data suggest a role for decreased endogenous NOS activity in the rebound pulmonary hypertension noted after acute withdrawal of inhaled NO.

scholarly journals Nitric Oxide Story

2019 ◽  
Vol 130 (3) ◽  
pp. 435-440 ◽  
Author(s):  
Warren M. Zapol
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Oxygen Saturation ◽  
Persistent Pulmonary Hypertension ◽  
Pulmonary Vasculature ◽  
Oxygen Tensions ◽  
Low Levels ◽  
Fraction Of Inspired Oxygen ◽  
Inspired Oxygen ◽  
Inhaled No

Abstract Inhaled Nitric Oxide in Persistent Pulmonary Hypertension of the Newborn. By Roberts JD, Polaner DM, Lang P, and Zapol WM. Lancet 1992; 130:435–40. Reprinted with permission. NO has vasodilatory effects on the pulmonary vasculature in adults and animals. We examined the effects on systemic oxygenation and blood pressure of inhaling up to 80 parts per million by volume of NO at fraction of inspired oxygen 0.9 for up to 30 min by six infants with persistent pulmonary hypertension of the newborn. In all infants, this treatment rapidly and significantly increased preductal oxygen saturation; in five infants, postductal oxygen saturation and oxygen tensions also increased. Inhalation of NO did not cause systemic hypotension or raise methemoglobin. These data suggest that low levels of inhaled NO have an important role in the reversal of hypoxemia due to persistent pulmonary hypertension of the newborn.

Inhibition of Endogenous Nitric Oxide Synthase Potentiates Nitrovasodilators in Experimental Pulmonary Hypertension

1996 ◽  
Vol 85 (4) ◽  
pp. 860-866 ◽  
Author(s):  
Brian P. Kavanagh ◽  
John S. Thompson ◽  
Ronald G. Pearl
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Sodium Nitroprusside ◽  
Dose Response ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
No Synthase ◽  
Pulmonary Vasculature ◽  
Response Characteristics ◽  
Endogenous Nitric Oxide

Background The role of endogenous nitric oxide (NO) in the regulation of pulmonary vascular tone is complex. Inhibition of endogenous NO synthase, potentially through upregulation of guanylyl cyclase, results in an increase in potency of nitrovasodilators in the systemic circulation. This study considered whether inhibition of endogenous NO synthase would increase the potency of nitrovasodilators, but not of cyclic adenosine monophosphate-dependent vasodilators, in the pulmonary vasculature. Methods We used the isolated buffer-perfused rabbit lung. Preparations were randomized to receive either pretreatment with NG-nitro-L-arginine methyl ester (or L-NAME, an inhibitor of endogenous NO synthase) or no pretreatment. Stable pulmonary hypertension was then produced by infusing the thromboxane A2 analog U46619. The dose-response characteristics of two nitrovasodilators, sodium nitroprusside and nitroglycerin, and two nonnitrovasodilators, prostaglandin E2 and 5'-N-ethylcarboxamidoadenosine, were studied. Results Inhibition of endogenous NO synthase caused no significant changes in baseline pulmonary artery pressure but did significantly reduce the U46619 infusion rate required to produce pulmonary hypertension. Pretreatment with L-NAME (vs. no L-NAME) resulted in significantly lower values of the log median effective dose with sodium nitroprusside and nitroglycerin. In contrast, pretreatment with L-NAME resulted in no changes in the dose-response characteristics of the cyclic adenosine monophosphate-mediated, NO-independent vasodilators prostaglandin E1 and 5'-N-ethylcarboxamidoadenosine. Conclusions These data suggest that endogenous NO synthase is not an important regulator of basal pulmonary tone in this model but is an important modulator of pulmonary vascular responses to vasoconstriction and to nitrovasodilators. The pulmonary vasodilator effects of nitrovasodilators, but not of nonnitrovasodilators, may depend on the level of activity of NO synthase.

Inhaled nitric oxide induced NOS inhibition and rebound pulmonary hypertension: a role for superoxide and peroxynitrite in the intact lamb

2006 ◽  
Vol 290 (2) ◽  
pp. L359-L366 ◽  
Author(s):  
Peter Oishi ◽  
Albert Grobe ◽  
Eileen Benavidez ◽  
Boaz Ovadia ◽  
Cynthia Harmon ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Inhaled Nitric Oxide ◽  
In Vivo Studies ◽  
Acute Increase ◽  
No Signaling ◽  
Oxide Synthase ◽  
Inhaled No

Previous in vivo studies indicate that inhaled nitric oxide (NO) decreases nitric oxide synthase (NOS) activity and that this decrease is associated with significant increases in pulmonary vascular resistance (PVR) upon the acute withdrawal of inhaled NO (rebound pulmonary hypertension). In vitro studies suggest that superoxide and peroxynitrite production during inhaled NO therapy may mediate these effects, but in vivo data are lacking. The objective of this study was to determine the role of superoxide in the decrease in NOS activity and rebound pulmonary hypertension associated with inhaled NO therapy in vivo. In control lambs, 24 h of inhaled NO (40 ppm) decreased NOS activity by 40% ( P < 0.05) and increased endothelin-1 levels by 64% ( P < 0.05). Withdrawal of NO resulted in an acute increase in PVR (60.7%, P < 0.05). Associated with these changes, superoxide and peroxynitrite levels increased more than twofold ( P < 0.05) following 24 h of inhaled NO therapy. However, in lambs treated with polyethylene glycol-conjugated superoxide dismutase (PEG-SOD) during inhaled NO therapy, there was no change in NOS activity, no increase in superoxide or peroxynitrite levels, and no increase in PVR upon the withdrawal of inhaled NO. In addition, endothelial NOS nitration was 18-fold higher ( P < 0.05) in control lambs than in PEG-SOD-treated lambs following 24 h of inhaled NO. These data suggest that superoxide and peroxynitrite participate in the decrease in NOS activity and rebound pulmonary hypertension associated with inhaled NO therapy. Reactive oxygen species scavenging may be a useful therapeutic strategy to ameliorate alterations in endogenous NO signaling during inhaled NO therapy.

scholarly journals Inhaled Nitric Oxide at Birth Reduces Pulmonary Vascular Resistance and Improves Oxygenation in Preterm Lambs

Children ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 378
Author(s):  
Satyan Lakshminrusimha ◽  
Sylvia F. Gugino ◽  
Krishnamurthy Sekar ◽  
Stephen Wedgwood ◽  
Carmon Koenigsknecht ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Pulmonary Vascular Resistance ◽  
Preterm Infants ◽  
Vascular Resistance ◽  
Inhaled Nitric Oxide ◽  
Persistent Pulmonary Hypertension ◽  
Inhaled No ◽  
Birth Preterm

Resuscitation with 21% O2 may not achieve target oxygenation in preterm infants and in neonates with persistent pulmonary hypertension of the newborn (PPHN). Inhaled nitric oxide (iNO) at birth can reduce pulmonary vascular resistance (PVR) and improve PaO2. We studied the effect of iNO on oxygenation and changes in PVR in preterm lambs with and without PPHN during resuscitation and stabilization at birth. Preterm lambs with and without PPHN (induced by antenatal ductal ligation) were delivered at 134 d gestation (term is 147–150 d). Lambs without PPHN were ventilated with 21% O2, titrated O2 to maintain target oxygenation or 21% O2 + iNO (20 ppm) at birth for 30 min. Preterm lambs with PPHN were ventilated with 50% O2, titrated O2 or 50% O2 + iNO. Resuscitation with 21% O2 in preterm lambs and 50%O2 in PPHN lambs did not achieve target oxygenation. Inhaled NO significantly decreased PVR in all lambs and increased PaO2 in preterm lambs ventilated with 21% O2 similar to that achieved by titrated O2 (41 ± 9% at 30 min). Inhaled NO increased PaO2 to 45 ± 13, 45 ± 20 and 76 ± 11 mmHg with 50% O2, titrated O2 up to 100% and 50% O2 + iNO, respectively, in PPHN lambs. We concluded that iNO at birth reduces PVR and FiO2 required to achieve target PaO2.

4971Blood viscosity and its relevance to the diagnosis and management of pulmonary hypertension: a new elephant in the cathlab

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
A Kempny ◽  
K Dimopoulos ◽  
A E Fraisse ◽  
G P Diller ◽  
L C Price ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Cardiac Catheterization ◽  
Clinical Decision Making ◽  
Clinical Decision ◽  
Pulmonary Vasculature ◽  
Pulmonary Vascular Disease ◽  
Significant Difference ◽  
The Difference ◽  
Clinically Significant ◽  
The Relationship

Abstract Background Pulmonary vascular resistance (PVR) is an essential parameter assessed during cardiac catheterization. It is used to confirm pulmonary vascular disease, to assess response to targeted pulmonary hypertension (PH) therapy and to determine the possibility of surgery, such as closure of intra-cardiac shunt or transplantation. While PVR is believed to mainly reflect the properties of the pulmonary vasculature, it is also related to blood viscosity (BV). Objectives We aimed to assess the relationship between measured (mPVR) and viscosity-corrected PVR (cPVR) and its impact on clinical decision-making. Methods We assessed consecutive PH patients undergoing cardiac catheterization. BV was assessed using the Hutton method. Results We included 465 patients (56.6% female, median age 63y). The difference between mPVR and cPVR was highest in patients with abnormal Hb levels (anemic patients: 5.6 [3.4–8.0] vs 7.8Wood Units (WU) [5.1–11.9], P<0.001; patients with raised Hb: 10.8 [6.9–15.4] vs. 7.6WU [4.6–10.8], P<0.001, respectively). Overall, 33.3% patients had a clinically significant (>2.0WU) difference between mPVR and cPVR, and this was more pronounced in those with anemia (52.9%) or raised Hb (77.6%). In patients in the upper quartile for this difference, mPVR and cPVR differed by 4.0WU [3.4–5.2]. Adjustment of PVR required Conclusions We report, herewith, a clinically significant difference between mPVR and cPVR in a third of contemporary patients assessed for PH. This difference is most pronounced in patients with anemia, in whom mPVR significantly underestimates PVR, whereas in most patients with raised Hb, mPVR overestimates it. Our data suggest that routine adjustment for BV is necessary.

Pulmonary vasodilation by nitric oxide gas and prodrug aerosols in acute pulmonary hypertension

1998 ◽  
Vol 84 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Christophe Adrie ◽  
Fumito Ichinose ◽  
Alexandra Holzmann ◽  
Larry Keefer ◽  
William E. Hurford ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Hypertension ◽  
Vascular Resistance ◽  
Pulmonary Circulation ◽  
Half Life ◽  
Hemodynamic Effects ◽  
Pulmonary Vasodilation ◽  
Short Half Life ◽  
Acute Pulmonary Hypertension ◽  
Inhaled No

Adrie, Christophe, Fumito Ichinose, Alexandra Holzmann, Larry Keefer, William E. Hurford, and Warren M. Zapol. Pulmonary vasodilation by nitric oxide gas and prodrug aerosols in acute pulmonary hypertension. J. Appl. Physiol. 84(2): 435–441, 1998.—Sodium 1-( N, N-diethylamino)diazen-1-ium-1,2-diolate {DEA/NO; Et2N[N(O)NO]Na} is a compound that spontaneously generates nitric oxide (NO). Because of its short half-life (2.1 min), we hypothesized that inhaling DEA/NO aerosol would selectively dilate the pulmonary circulation without decreasing systemic arterial pressure. We compared the pulmonary selectivity of this new NO donor with two other reference drugs: inhaled NO and inhaled sodium nitroprusside (SNP). In seven awake sheep with pulmonary hypertension induced by the infusion of U-46619, we compared the hemodynamic effects of DEA/NO with those of incremental doses of inhaled NO gas. In seven additional awake sheep, we examined the hemodynamic effects of incremental doses of inhaled nitroprusside (i.e., SNP). Inhaled NO gas selectively dilated the pulmonary vasculature. Inhaled DEA/NO produced nonselective vasodilation; both systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) were reduced. Inhaled SNP selectively dilated the pulmonary circulation at low concentrations (≤10−2 M), inducing a decrease of PVR of up to 42% without any significant decrease of SVR (−5%), but nonselectively dilated the systemic circulation at larger doses (>10−2 M). In conclusion, despite its short half-life, DEA/NO is not a selective pulmonary vasodilator compared with inhaled NO. Inhaled SNP appears to be selective to the pulmonary circulation at low doses but not at higher levels.

Comparison of the hemodynamic effects of nitric oxide and endothelium-dependent vasodilators in intact lungs

1990 ◽  
Vol 68 (2) ◽  
pp. 735-747 ◽  
Author(s):  
S. L. Archer ◽  
K. Rist ◽  
D. P. Nelson ◽  
E. G. DeMaster ◽  
N. Cowan ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Methylene Blue ◽  
Pulmonary Hypertension ◽  
Feedback Inhibition ◽  
Pressor Response ◽  
Pulmonary Vasculature ◽  
Hemodynamic Effects ◽  
Isolated Lung

The effects of endothelium-dependent vasodilation on pulmonary vascular hemodynamics were evaluated in a variety of in vivo and in vitro models to determine 1) the comparability of the hemodynamic effects of acetylcholine (ACh), bradykinin (BK), nitric oxide (NO), and 8-bromo-guanosine 3′,5′-cyclic monophosphate (cGMP), 2) whether methylene blue is a useful inhibitor of endothelium-dependent relaxing factor (EDRF) activity in vivo, and 3) the effect of monocrotaline-induced pulmonary hypertension on the responsiveness of the pulmonary vasculature to ACh. In isolated rat lungs, which were preconstricted with hypoxia, ACh, BK, NO, and 8-bromo-cGMP caused pulmonary vasodilation, which was not inhibited by maximum tolerable doses of methylene blue. Methylene blue did not inhibit EDRF activity in any model, despite causing increased pulmonary vascular tone and responsiveness to various constrictor agents. There were significant differences in the hemodynamic characteristics of ACh, BK, and NO. In the isolated lung, BK and NO caused transient decreases of hypoxic vasoconstriction, whereas ACh caused more prolonged vasodilation. Pretreatment of these lungs with NO did not significantly inhibit ACh-induced vasodilation but caused BK to produce vasoconstriction. Tachyphylaxis, which was agonist specific, developed with repeated administration of ACh or BK but not NO. Tachyphylaxis probably resulted from inhibition of the endothelium-dependent vasodilation pathway proximal to NO synthesis, because it could be overcome by exogenous NO. Pretreatment with 8-bromo-cGMP decreased hypoxic pulmonary vasoconstriction and, even when the hypoxic pressor response had largely recovered, subsequent doses of ACh and NO failed to cause vasodilation, although BK produced vasoconstriction. These findings are compatible with the existence of feedback inhibition of the endothelium-dependent relaxation by elevation of cGMP levels. Responsiveness to ACh was retained in lungs with severe monocrotaline-induced pulmonary hypertension. Many of these findings would not have been predicted based on in vitro studies and illustrate the importance for expanding studies of EDRF to in vivo and ex vivo models.

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