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.

Functional and structural changes with hypoxia in pulmonary circulation of spontaneously hypertensive rats

1994 ◽  
Vol 77 (3) ◽  
pp. 1101-1107 ◽  
Author(s):  
S. P. Janssens ◽  
B. T. Thompson ◽  
C. R. Spence ◽  
C. A. Hales
Keyword(s):  
Pulmonary Hypertension ◽  
Arterial Pressure ◽  
Vascular Remodeling ◽  
Spontaneously Hypertensive Rats ◽  
Structural Changes ◽  
Chronic Hypoxia ◽  
Acute Hypoxia ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto

Chronic hypoxic pulmonary hypertension involves both vasoconstriction and vascular remodeling. Spontaneously hypertensive rats (SHR) have an increased systemic vascular resistance and a greater responsiveness to constricting stimuli. We hypothesized that, in contrast to age-matched normotensive Wistar-Kyoto rats (WKY), SHR also display spontaneous pulmonary hypertension in normoxia and increased vascular response to acute and chronic hypoxia. Baseline mean pulmonary arterial pressure (PAP) and total pulmonary resistance (TPR) were higher in SHR than in WKY. With acute hypoxia (10% O2 for 15 min), PAP increased to the same extent in SHR and WKY and cardiac output (CO) was unchanged in WKY but increased in SHR. Thus, the rise in PAP in the SHR might be accounted for by the rise in CO, as TPR did not rise, but not that in the WKY, as TPR increased. After 12 days in hypoxia (10% O2), mean arterial pressure was unchanged in WKY but decreased significantly in SHR without a change in CO. PAP increased by 59% in SHR and 54% in WKY when the rats were taken from the hypoxic chamber for 1 h. Acute hypoxic challenge caused a further increase in PAP only in WKY. Medial wall thickness of alveolar duct and terminal bronchial vessels was similar in WKY and SHR after chronic hypoxia. We conclude that SHR exhibit mild baseline pulmonary hypertension in normoxia and that chronic hypoxia does not produce a disproportionate increase in SHR pulmonary vascular remodeling and pulmonary hypertension.

Pulmonary vascular iNOS induction participates in the onset of chronic hypoxic pulmonary hypertension

2006 ◽  
Vol 290 (1) ◽  
pp. L11-L20 ◽  
Author(s):  
Václav Hampl ◽  
Jana Bíbová ◽  
Alena Baňasová ◽  
Jiří Uhlík ◽  
Dana Miková ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Drinking Water ◽  
Arterial Pressure ◽  
Tissue Injury ◽  
Vascular Wall ◽  
Systemic Arterial Pressure ◽  
No Production ◽  
Hypoxic Pulmonary Hypertension ◽  
Inos Inhibitor ◽  
Inos Induction

Pathogenesis of hypoxic pulmonary hypertension is initiated by oxidative injury to the pulmonary vascular wall. Because nitric oxide (NO) can contribute to oxidative stress and because the inducible isoform of NO synthase (iNOS) is often upregulated in association with tissue injury, we hypothesized that iNOS-derived NO participates in the pulmonary vascular wall injury at the onset of hypoxic pulmonary hypertension. An effective and selective dose of an iNOS inhibitor, l- N6-(1-iminoethyl)lysine (l-NIL), for chronic peroral treatment was first determined (8 mg/l in drinking water) by measuring exhaled NO concentration and systemic arterial pressure after LPS injection under ketamine+xylazine anesthesia. A separate batch of rats was then exposed to hypoxia (10% O2) and given l-NIL or a nonselective inhibitor of all NO synthases, NG-nitro-l-arginine methyl ester (l-NAME, 500 mg/l), in drinking water. Both inhibitors, applied just before and during 1-wk hypoxia, equally reduced pulmonary arterial pressure (PAP) measured under ketamine+xylazine anesthesia. If hypoxia continued for 2 more wk after l-NIL treatment was discontinued, PAP was still lower than in untreated hypoxic controls. Immunostaining of lung vessels showed negligible iNOS presence in control rats, striking iNOS expression after 4 days of hypoxia, and return of iNOS immunostaining toward normally low levels after 20 days of hypoxia. Lung NO production, measured as NO concentration in exhaled air, was markedly elevated as early as on the first day of hypoxia. We conclude that transient iNOS induction in the pulmonary vascular wall at the beginning of chronic hypoxia participates in the pathogenesis of pulmonary hypertension.

E-4010, a selective phosphodiesterase 5 inhibitor, attenuates hypoxic pulmonary hypertension in rats

1999 ◽  
Vol 277 (2) ◽  
pp. L225-L232 ◽  
Author(s):  
Norihisa Hanasato ◽  
Masahiko Oka ◽  
Masashi Muramatsu ◽  
Mayu Nishino ◽  
Hideyuki Adachi ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Right Ventricular ◽  
Ventricular Hypertrophy ◽  
Chronic Hypoxia ◽  
Systemic Arterial Pressure ◽  
Right Ventricular Hypertrophy ◽  
Pulmonary Arterial

The purpose of this study was to determine whether E-4010, a newly synthesized potent and selective orally active phosphodiesterase (PDE) 5 inhibitor, would prevent the development of chronic hypoxia-induced pulmonary hypertension in rats. In conscious, pulmonary hypertensive rats, a single oral administration of E-4010 (1.0 mg/kg) caused an acute, long-lasting reduction in mean pulmonary arterial pressure (PAP), with no significant effects on systemic arterial pressure, cardiac output, and heart rate. In rats that received food containing 0.01 or 0.1% E-4010 during the 3-wk exposure to hypoxia, mean PAP was significantly decreased (mean PAP 24.0 ± 0.9, 16.2 ± 0.8, and 12.8 ± 0.5 mmHg in rats treated with 0, 0.01, and 0.1% E-4010-containing food, respectively), whereas mean systemic arterial pressure was unchanged and cardiac output was slightly increased compared with chronically hypoxic control rats. Right ventricular hypertrophy, medial wall thickness in pulmonary arteries corresponding to the respiratory and terminal bronchioles, and the degree of muscularization of more distal arteries were less severe in E-4010-treated rats. Long-term treatment with E-4010 caused an increase in cGMP levels in lung tissue and plasma but not in aortic tissue and no significant change in cAMP levels in either lung, aorta, or plasma. These results suggest that long-term oral treatment with E-4010 reduced the increase in PAP, right ventricular hypertrophy, and pulmonary arterial remodeling induced by exposure to chronic hypoxia, probably through increasing cGMP levels in the pulmonary vascular smooth muscle.

Pulmonary vascular response to endothelin in rats

1991 ◽  
Vol 70 (2) ◽  
pp. 567-574 ◽  
Author(s):  
B. Raffestin ◽  
S. Adnot ◽  
S. Eddahibi ◽  
I. Macquin-Mavier ◽  
P. Braquet ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Vascular Resistance ◽  
Systemic Circulation ◽  
Systemic Arterial Pressure ◽  
Vascular Response ◽  
Autonomic Blockade ◽  
Initial Drop ◽  
Pulmonary Arterial ◽  
Isolated Lungs ◽  
Dose Dependent Increase

This study investigated the pulmonary vascular response to endothelin (ET) in rats. In conscious rats, an incremental intravenous bolus of ET-1 (100-1,000 pM) caused, after an initial drop in systemic arterial pressure (Psa), a secondary dose-dependent increase of Psa concomitant with a decrease of cardiac output (CO) and heart rate (HR). Pulmonary arterial pressure (Ppa) remained unchanged, and pulmonary vascular resistance (PVR) increased significantly only after 1,000 pM (+ 40.0 +/- 10.4 at 15 min). Meclofenamate (6 mg/kg iv) did not alter hemodynamic response to ET (300 pM). After autonomic blockade with hexamethonium (6 mg/kg iv) plus atropine (0.75 mg/kg iv), bradycardia response to ET (300 pM) was blocked, but CO decreased, systemic vascular resistance increased, and PVR remained unchanged as in controls. In anesthetized ventilated rats, bolus injections of ET (10-1,000 pM) induced a transient dose-related decrease in compliance (-10.9 +/- 1.8% after 1,000 pM) but no change of conductance. In isolated lungs, Ppa increased at doses greater than 100 pM, and edema developed in response to 1,000 pM ET. The rise of Ppa in response to 300 pM was not altered by meclofenamate (3.2 x 10(-6) M) but was potentiated by inhibitors of endothelium-derived relaxing factor(s) (EDRF), methylene blue (10(-4) M), pyrogallol (3 x 10(-5) M), and NG-monomethyl-L-arginine (6 x 10(-4) M) (3.9 +/- 0.3, 4.6 +/- 0.5, and 5.9 +/- 0.3 mmHg, respectively, compared with 1.5 +/- 0.5 mmHg in control lungs). These results suggest that circulating ET is a more potent constrictor of the systemic circulation than of the pulmonary vascular bed.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of airway wall blood flow in sheep by laser-Doppler flowmetry: interpretation and problems

1991 ◽  
Vol 70 (2) ◽  
pp. 641-649 ◽  
Author(s):  
D. J. Godden ◽  
E. M. Wagner ◽  
P. D. Pare ◽  
W. Mitzner ◽  
E. M. Baile
Keyword(s):  
Arterial Pressure ◽  
Vascular Resistance ◽  
Systemic Circulation ◽  
Systemic Arterial Pressure ◽  
Doppler Flowmetry ◽  
Autonomic Blockade ◽  
Initial Drop ◽  
Pulmonary Arterial ◽  
Isolated Lungs ◽  
Dose Dependent Increase

This study investigated the pulmonary vascular response to endothelin (ET) in rats. In conscious rats, an incremental intravenous bolus of ET-1 (100-1,000 pM) caused, after an initial drop in systemic arterial pressure (Psa), a secondary dose-dependent increase of Psa concomitant with a decrease of cardiac output (CO) and heart rate (HR). Pulmonary arterial pressure (Ppa) remained unchanged, and pulmonary vascular resistance (PVR) increased significantly only after 1,000 pM (+ 40.0 +/- 10.4 at 15 min). Meclofenamate (6 mg/kg iv) did not alter hemodynamic response to ET (300 pM). After autonomic blockade with hexamethonium (6 mg/kg iv) plus atropine (0.75 mg/kg iv), bradycardia response to ET (300 pM) was blocked, but CO decreased, systemic vascular resistance increased, and PVR remained unchanged as in controls. In anesthetized ventilated rats, bolus injections of ET (10-1,000 pM) induced a transient dose-related decrease in compliance (-10.9 +/- 1.8% after 1,000 pM) but no change of conductance. In isolated lungs, Ppa increased at doses greater than 100 pM, and edema developed in response to 1,000 pM ET. The rise of Ppa in response to 300 pM was not altered by meclofenamate (3.2 x 10(-6) M) but was potentiated by inhibitors of endothelium-derived relaxing factor(s) (EDRF), methylene blue (10(-4) M), pyrogallol (3 x 10(-5) M), and NG-monomethyl-L-arginine (6 x 10(-4) M) (3.9 +/- 0.3, 4.6 +/- 0.5, and 5.9 +/- 0.3 mmHg, respectively, compared with 1.5 +/- 0.5 mmHg in control lungs). These results suggest that circulating ET is a more potent constrictor of the systemic circulation than of the pulmonary vascular bed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute and chronic hypoxic pulmonary hypertension in guinea pigs

1989 ◽  
Vol 66 (2) ◽  
pp. 920-928 ◽  
Author(s):  
B. T. Thompson ◽  
P. M. Hassoun ◽  
R. L. Kradin ◽  
C. A. Hales
Keyword(s):  
Pulmonary Hypertension ◽  
Cardiac Index ◽  
Guinea Pigs ◽  
Chronic Hypoxia ◽  
Acute Hypoxia ◽  
Pulmonary Arteries ◽  
Initial Response ◽  
Hypoxic Pulmonary Hypertension ◽  
Mean Pulmonary Arterial Pressure ◽  
Chronic Pulmonary Hypertension

To determine whether the strength of acute hypoxic vasoconstriction predicts the magnitude of chronic hypoxic pulmonary hypertension, we performed serial studies on guinea pigs. Unanesthetized, chronically catheterized guinea pigs increased mean pulmonary arterial pressure (PAP) from 11 +/- 0.5 to 13 +/- 0.7 Torr in acute hypoxia (10% O2 for 65 min). The response was maximal at 5 min, remained stable for 1 h, and was reversible on return to room air. Cardiac index did not change with acute hypoxia or recovery. Guinea pigs exposed to chronic hypoxia increased PAP, measured in room air 1 h after removal from the hypoxic chamber, to 18 +/- 1 Torr by 5 days with little further increase in PAP to 20 +/- 1 Torr after 21 days. Cardiac index fell from 273 +/- 12 to 206 +/- 7 ml.kg-1.min-1 (P less than 0.05) after 21 days of hypoxia. Medial thickness of pulmonary arteries adjacent to terminal bronchioles and alveolar ducts increased significantly by 10 days. The magnitude of the pulmonary vasoconstriction to acute hypoxia persisted and was unabated during the development and apparent stabilization of chronic hypoxic pulmonary hypertension, suggesting that if vasoconstriction is the stimulus for remodeling, then the importance of the stimulus lessens with duration of hypoxia. In individual animals followed serially, we found no correlation between the magnitude of the acute vasoconstrictor response before chronic hypoxia and the severity of chronic pulmonary hypertension that subsequently developed either because the initial response was small and variable or because vasoconstriction may not be the sole stimulus for vascular remodeling in the guinea pig.

Enhanced endothelin-1 and endothelin receptor gene expression in chronic hypoxia

1994 ◽  
Vol 77 (3) ◽  
pp. 1451-1459 ◽  
Author(s):  
H. Li ◽  
S. J. Chen ◽  
Y. F. Chen ◽  
Q. C. Meng ◽  
J. Durand ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Pulmonary Artery ◽  
Arterial Pressure ◽  
Chronic Hypoxia ◽  
Pulmonary Arterial Pressure ◽  
Mrna Levels ◽  
Hypoxic Pulmonary Hypertension ◽  
Receptor Mrna ◽  
Etb Receptor ◽  
Pulmonary Arterial

To test the hypothesis that endothelin (ET)-1 synthesis and ET receptor levels are increased selectively in the lung of rats with chronic hypoxic pulmonary hypertension, the current study examined the effects of exposure to chronic hypoxia (10% O2, 1 atm, 4 wk) on pulmonary arterial pressure, ET-1 levels in plasma and lung, and ET-1 and ETA and ETB receptor mRNA levels in lung, heart, pulmonary artery, aorta, kidney, spleen, and liver. Hypoxic exposure was associated with increases in pulmonary arterial pressure, plasma ET-1 levels, ET-1 mRNA in lung and pulmonary artery, and ET-1 stores and ETA and ETB receptor mRNA levels in lung. In thoracic aorta and the four heart chambers, ETA and ETB receptor mRNA levels were increased, but ET-1 mRNA levels were unchanged from air control levels. No change in ET-1 or ET receptor mRNA levels was seen in organs perfused by the systemic vascular bed, except in liver, where ETA receptor mRNA levels were decreased. The findings of concomitant increases in gene transcript levels for ET-1 and the ETA and ETB receptors in lung, but not in the great vessels or any other organ examined, are consistent with the hypothesis that increased ET-1 synthesis in the lung contributes to pulmonary vascular remodeling and the maintenance of chronic hypoxic pulmonary hypertension.

Metalloproteinase inhibition by Batimastat attenuates pulmonary hypertension in chronically hypoxic rats

2003 ◽  
Vol 285 (1) ◽  
pp. L199-L208 ◽  
Author(s):  
Jan Herget ◽  
Jana Novotná ◽  
Jana Bíbová ◽  
Viera Povýšilová ◽  
Marie Vaňková ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Vascular Remodeling ◽  
Chronic Hypoxia ◽  
Causative Factor ◽  
Systemic Arterial Pressure ◽  
Collagenolytic Activity ◽  
Pulmonary Vascular Remodeling ◽  
Arterial Blood ◽  
Fraction Of Inspired Oxygen ◽  
Lung Vessels

Chronic hypoxia induces lung vascular remodeling, which results in pulmonary hypertension. We hypothesized that a previously found increase in collagenolytic activity of matrix metalloproteinases during hypoxia promotes pulmonary vascular remodeling and hypertension. To test this hypothesis, we exposed rats to hypoxia (fraction of inspired oxygen = 0.1, 3 wk) and treated them with a metalloproteinase inhibitor, Batimastat (30 mg/kg body wt, daily ip injection). Hypoxia-induced increases in concentration of collagen breakdown products and in collagenolytic activity in pulmonary vessels were inhibited by Batimastat, attesting to the effectiveness of Batimastat administration. Batimastat markedly reduced hypoxic pulmonary hypertension: pulmonary arterial blood pressure was 32 ± 3 mmHg in hypoxic controls, 24 ± 1 mmHg in Batimastat-treated hypoxic rats, and 16 ± 1 mmHg in normoxic controls. Right ventricular hypertrophy and muscularization of peripheral lung vessels were also diminished. Batimastat had no influence on systemic arterial pressure or cardiac output and was without any effect in rats kept in normoxia. We conclude that stimulation of collagenolytic activity in chronic hypoxia is a substantial causative factor in the pathogenesis of pulmonary vascular remodeling and hypertension.

scholarly journals The Effects of Inhalation of a Novel Nitric Oxide Donor, DETA/NO, in a Patient with Severe Hypoxaemia Due to Acute Respiratory Distress Syndrome

2002 ◽  
Vol 30 (4) ◽  
pp. 472-476 ◽  
Author(s):  
C. F. Lam ◽  
P. V. Van Heerden ◽  
S. Sviri ◽  
B. L. Roberts ◽  
K. F. Ilett
Keyword(s):  
Nitric Oxide ◽  
Acute Respiratory Distress Syndrome ◽  
Arterial Pressure ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Resistance Index ◽  
Systemic Circulation ◽  
Systemic Arterial Pressure ◽  
Nitric Oxide Donor

Aerosolized NONOates have been investigated in animal models in acute pulmonary hypertension, but none have been used in humans. We report the first use of aerosolized diethylenetriamine nitric oxide adduct (DETA/NO), a NONOate, in a patient with severe acute respiratory distress syndrome. Both pulmonary vascular resistance index and mean pulmonary arterial pressure were reduced by a mean of 26% and 18% respectively after the administration of a single dose of DETA/NO (150 μmol). Intrapulmonary shunting also improved. There were no significant changes in systemic arterial pressure or arterial methaemoglobin concentration after DETA/NO inhalation. We conclude that DETA/NO aerosol produced selective pulmonary vasodilation, with an improvement in pulmonary haemodynamics and oxygenation, while having no measurable effect on the systemic circulation.

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