Bleomycin-induced lung injury in rats selectively abolishes hypoxic pulmonary vasoconstriction: Evidence against a role for platelet-activating factor

1992 ◽  
Vol 82 (3) ◽  
pp. 259-264 ◽  
Author(s):  
David G. McCormack ◽  
David E. Crawley ◽  
Peter J. Barnes ◽  
Timothy W. Evans
Keyword(s):  
Angiotensin Ii ◽  
Lung Injury ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Platelet Activating Factor ◽  
Saline Control ◽  
Lung Weight ◽  
Intratracheal Administration ◽  
Pulmonary Vasoconstriction ◽  
Web 2086

1. The role of platelet-activating factor in the attenuated hypoxic pulmonary vasoconstriction associated with lung injury was evaluated using specific platelet-activating factor antagonists and an isolated perfused lung preparation. 2. Intratracheal bleomycin was administered to rats to produce acute lung injury. Animals received intratracheal saline (control), intratracheal bleomycin or the platelet-activating factor anatagonists BN 52021, WEB 2170 or WEB 2086 before and after bleomycin treatment. Forty-eight hours after intratracheal administration of bleomycin or saline the animals were killed. 3. The increases in pulmonary artery pressure during two periods of hypoxic ventilation and in response to 0.2 μg of angiotensin II were measured. Acetylcholine-induced vasodilatation after pre-constriction with prostaglandin F2α was also measured. To quantify lung injury, the wet/ dry ratio of lung weight was determined. 4. Bleomycin treatment attenuated the first and second hypoxic pressor responses by 93% and 77%, respectively, but not the pressor response to angiotensin II nor the vasodilator response to acetylcholine. BN 52021 plus bleomycin augmented the first hypoxic pressor response compared with bleomycin treatment alone, but the structurally unrelated platelet-activating factor antagonists WEB 2170 and WEB 2086 had no significant effect on the bleomycin-induced attenuation of hypoxic pulmonary vasoconstriction. None of the platelet-activating factor antagonists blocked the increase in the wet/dry lung weight ratio induced by bleomycin. 5. Bleomycin-induced lung injury selectively attenuates hypoxic pulmonary vasoconstriction, an effect that does not appear to be mediated by platelet-activating factor. The mechanism remains to be elucidated, but may involve destruction of the hypoxic ‘sensor’ within the respiratory tract.

Evidence against a Role for Platelet-Activating Factor in Hypoxic Pulmonary Vasoconstriction in the Rat

1989 ◽  
Vol 77 (4) ◽  
pp. 439-443 ◽  
Author(s):  
D. G. McCormack ◽  
P. J. Barnes ◽  
T. W. Evans
Keyword(s):  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Platelet Activating Factor ◽  
Pulmonary Vasoconstriction ◽  
Paf Receptor ◽  
Pre Treatment ◽  
Dose Dependent ◽  
Higher Doses ◽  
Lung Preparation ◽  
Web 2086

1. The effect of two structurally different platelet-activating factor (PAF) receptor antagonists, WEB 2086({3-[4-(2-chlorophenyl)-9-methyl-6H-thieno[3,2-f]-[1,2,4]-treazolo-[4,3-a][1,4]-diazepine-2-yl]-1-(morpholinyl)-1-propanone}) and BN 52021, on hypoxic pulmonary vasoconstriction (HPV) was studied using an isolated rat lung preparation perfused with blood. 2. In lungs treated with WEB 2086 there was a dose-dependent attenuation of HPV, with complete abolition of HPV at the maximum dose. 3. Low doses of WEB 2086 caused only slight diminution of the pressor response to angiotensin II, although higher doses caused increasing attenuation of the angiotensin pressor response. 4. BN 52021 did not affect HPV. 5. Injection of PAF caused an increase in pulmonary artery pressure of 145%, a response abolished by pre-treatment of the lungs with either WEB 2086 or BN 52021. 6. These results suggest that PAF does not mediate HPV in the rat.

Leukotriene synthesis and receptor blockers block hypoxic pulmonary vasoconstriction

1984 ◽  
Vol 56 (5) ◽  
pp. 1340-1346 ◽  
Author(s):  
M. L. Morganroth ◽  
J. T. Reeves ◽  
R. C. Murphy ◽  
N. F. Voelkel
Keyword(s):  
Angiotensin Ii ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Calcium Entry ◽  
Calcium Entry Blocker ◽  
Adult Rat ◽  
Pulmonary Vasoconstriction ◽  
Rat Lungs ◽  
Diethylcarbamazine Citrate ◽  
Receptor Blockers

We hypothesized that leukotrienes are involved in hypoxic pulmonary vasoconstriction, since they are pulmonary vasoconstrictors and cells capable of producing leukotrienes are located in the lung near resistance vessels. We investigated in isolated perfused rat lungs whether three structurally unrelated blockers [diethylcarbamazine citrate (DEC), U-60257, and FPL 55712] of leukotriene synthesis or action block hypoxic pulmonary vasoconstriction. DEC blocked ongoing and subsequent hypoxic pressor responses while minimally affecting the angiotensin II pressor response. The inhibition of the hypoxic pressor response by DEC was not affected by cyclooxygenase or H1-receptor blockers. Potassium-induced vasoconstriction, which is dependent on calcium entry, was largely blocked by verapamil but not by DEC, suggesting that DEC was not acting primarily as a calcium-entry blocker. U-60257 blocked the hypoxic pressor response without inhibiting the pressor response to angiotensin II or potassium chloride. FPL 55712, a leukotriene end-organ blocker, in a dose which inhibited vasoconstriction caused by exogenous leukotriene C4, inhibited the pressor response to hypoxia but not to angiotensin II. We conclude that leukotriene inhibitors preferentially inhibit hypoxic pulmonary vasoconstriction in isolated perfused adult rat lungs.

Reactive Oxygen Species Scavengers Attenuate Endotoxin-induced Impairment of Hypoxic Pulmonary Vasoconstriction in Mice

2002 ◽  
Vol 97 (5) ◽  
pp. 1227-1233 ◽  
Author(s):  
Hemanth A. Baboolal ◽  
Fumito Ichinose ◽  
Roman Ullrich ◽  
Noriko Kawai ◽  
Kenneth D. Bloch ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Lung Injury ◽  
Saline Solution ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Intratracheal Administration ◽  
Endotoxin Challenge ◽  
Pulmonary Vasoconstriction ◽  
Ros Scavengers

Background Sepsis and endotoxemia attenuate hypoxic pulmonary vasoconstriction (HPV), thereby impairing systemic oxygenation. Reactive oxygen species (ROS) are implicated in the pathogenesis of sepsis-induced lung injury. The authors investigated whether treatment with scavengers of ROS prevents impairment of HPV in mice challenged with endotoxin. Methods The pulmonary vasoconstrictor response to left mainstem bronchus occlusion (LMBO) was studied in anesthetized mice 22 h after an intraperitoneal challenge with saline solution or 10 mg/kg Escherichia coli endotoxin. In some mice, challenge with saline solution or endotoxin was followed after 1 h with intraperitoneal or intratracheal administration of the ROS scavengers N-acetylcysteine or EUK-8. Myeloperoxidase activity and nitric oxide synthase-2 gene expression were measured in lung tissues. Results The LMBO increased left pulmonary vascular resistance by 106 +/- 24% in saline-challenged control mice but by only 23 +/- 12% (P < 0.05) in endotoxin-challenged mice. Intraperitoneal administration of N-acetylcysteine or EUK-8 1 h after endotoxin challenge attenuated the endotoxin-induced impairment of HPV (58 +/- 6% and 68 +/- 10%, respectively; both P< 0.05 endotoxin-challenged mice). Intratracheal administration of ROS scavengers 1 h after endotoxin challenge was equally effective but required lower doses than systemic treatment. Administration of the ROS scavengers 22 h after endotoxin challenge did not restore HPV. Conclusions Administration of N-acetylcysteine or EUK-8 1 h after endotoxin challenge in mice prevented the impairment of HPV after LMBO. Early therapy with ROS scavengers, either systemically or by inhalation, may provide a means to preserve HPV in sepsis-associated acute lung injury.

Pulmonary vascular reactivity: effect of PAF and PAF antagonists

1992 ◽  
Vol 73 (5) ◽  
pp. 1762-1769 ◽  
Author(s):  
C. R. Chen ◽  
N. F. Voelkel ◽  
S. W. Chang
Keyword(s):  
Angiotensin Ii ◽  
Vascular Reactivity ◽  
Platelet Activating Factor ◽  
Lung Edema ◽  
Physiological Salt Solution ◽  
Similar Response ◽  
Pulmonary Vasodilation ◽  
Pulmonary Vasoconstriction ◽  
Paf Antagonists ◽  
Web 2086

We investigated the effects of two different platelet-activating factor (PAF) antagonists, SRI 63–441 and WEB 2086, on PAF-, angiotensin II-, and hypoxia-induced vasoconstrictions in isolated rat lungs perfused with a physiological salt solution. Bolus injection of PAF (0.5 micrograms) increased pulmonary arterial and microvascular pressures and caused lung edema. Both SRI 63–441, a PAF-analogue antagonist, and WEB 2086, a thienotriazolodiazepine structurally unrelated to PAF, completely blocked PAF-induced vasoconstriction and lung edema at 10(-5) M. At a lower concentration (10(-6) M), WEB 2086 was more effective than SRI 63–441. WEB 2086 also blocked the pulmonary vasodilation induced by low-dose PAF (15 ng) in blood-perfused lungs preconstricted with hypoxia. SRI 63–441 and CV 3988 (another PAF analogue antagonist), but not WEB 2086, caused acute pulmonary vasoconstriction at 10(-5) M and severe lung edema at a higher concentration (10(-4) M). PAF-induced but not SRI- or CV-induced pulmonary vasoconstriction and edema were inhibited by WEB 2086. In addition, SRI 63–441 potentiated angiotensin II- and hypoxia-induced vasoconstrictions. This effect of SRI 63-441 is not due to PAF receptor blockade because 1) addition of PAF (1.6 nM) to the perfusate likewise potentiated angiotensin II-induced vasoconstriction and 2) WEB 2086 did not cause a similar response. We conclude that both SRI 63–441 and WEB 2086 are effective inhibitors of PAF actions in the rat pulmonary circulation. However, antagonists with structures analogous to PAF (SRI 63–441 and CV 3988) can have significant pulmonary vasoactive side effects.

Loss of hypoxic pulmonary vasoconstriction in chronic pneumonia is not mediated by nitric oxide

1993 ◽  
Vol 265 (5) ◽  
pp. H1523-H1528 ◽  
Author(s):  
D. G. McCormack ◽  
N. A. Paterson
Keyword(s):  
Nitric Oxide ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Sprague Dawley ◽  
Absolute Increase ◽  
Pulmonary Vasoconstriction ◽  
Sprague Dawley Rats ◽  
Before And After ◽  
Inflammatory Processes ◽  
The Difference

In pulmonary inflammatory processes such as pneumonia there is diminished hypoxic pulmonary vasoconstriction (HPV). We investigated whether the attenuated HPV in pneumonia is a due to excess nitric oxide (NO) release. Sprague-Dawley rats were anesthetized, and a slurry (0.06 ml) of infected agar beads (containing 6 x 10(5) Pseudomonas aeruginosa organisms) or control (sterile) beads was then injected into a distal bronchus through a tracheotomy. After the establishment of a chronic P. aeruginosa pneumonia (7-10 days later) animals were instrumented for hemodynamic monitoring, and the response to exposure to hypoxic gas (fraction of inspired O2 = 0.08) was recorded before and after the administration of NG-monomethyl-L-arginine (L-NMMA; 50 mg/kg), an inhibitor of NO synthesis. The hypoxic pressor response, as assessed by the absolute increase in pulmonary arterial pressure (PAP) and total pulmonary resistance (TPR), was reduced in infected animals compared with control animals. The change in PAP and TPR was 8.5 +/- 0.7 and 0.053 +/- 0.007, respectively, in control animals compared with 5.9 +/- 0.5 and 0.041 +/- 0.011 in infected animals. After L-NMMA the increase in PAP and TPR during hypoxia was greater in both control and infected animals. However, treatment with L-NMMA did not affect the difference between control and infected animals. We conclude that excess release of NO does not account for the attenuated hypoxic pressor response in pneumonia.

Microvascular hemodynamics in the sickle red blood cell perfused isolated rat lung

1993 ◽  
Vol 264 (2) ◽  
pp. H484-H489 ◽  
Author(s):  
J. Haynes ◽  
A. E. Taylor ◽  
D. Dixon ◽  
N. Voelkel
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Weight Ratio ◽  
Gas Mixture ◽  
Low Oxygen ◽  
Lung Water ◽  
Lung Weight ◽  
Normal Human

In this study the effects of alveolar hypoxia on pulmonary microvascular hemodynamics in sickle red blood cell (HbSS-RBC) perfused rat lungs were studied under conditions of high and low oxygen tensions and compared with lung perfused with rat (HbRat) and normal human (HbAA) RBC controls. Independent of the RBC suspension (hematocrit 5%) used, ventilation with the room air gas mixture did not result in any significant differences in the pulmonary arterial pressure (Ppa), capillary pressure (Ppc), total pulmonary vascular resistance (RT), or angiotensin II pressor response. Ventilation of HbSS-RBC perfused lungs with a hypoxic gas mixture significantly increased the Ppa, Ppc, and RT above that which was seen in HbRat and HbAA controls. The increase in RT occurred mainly in the pulmonary artery independent of RBC suspension. In addition, no significant accumulation of lung water occurred in HbSS-RBC perfused lungs compared with HbRat and HbAA controls, as indicated by the change in capillary filtration coefficient and wet-to-dry lung weight ratio. In conclusion, deoxygenation of the HbSS-RBC and hypoxic pulmonary vasoconstriction is additive in altering pulmonary microvascular hemodynamics.

Effects of ouabain, low K+, and aldosterone on hypoxic pressor reactivity of rat lungs

1985 ◽  
Vol 248 (1) ◽  
pp. H55-H60 ◽  
Author(s):  
J. Herget ◽  
I. F. McMurtry
Keyword(s):  
Angiotensin Ii ◽  
Energy Metabolism ◽  
Atpase Activity ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Response Curves ◽  
Hypoxic Response ◽  
Rat Lungs ◽  
Hypoxic Vasoconstriction ◽  
Low K

It can be postulated that inhibition of lung tissue Na+-K+-ATPase might potentiate hypoxic pulmonary vasoconstriction by depolarizing some excitable cell or, in contrast, that it might blunt the hypoxic response by reducing cellular metabolic rate and sensitivity to hypoxia. Thus the purpose of this study was to test in isolated rat lungs whether hypoxic pressor reactivity was related inversely or positively to Na+-K+-ATPase activity. Dose-pressor response curves to hypoxia, angiotensin II, or KCl were measured under control conditions and after exposure either to one of two inhibitors of Na+-K+-ATPase, ouabain, and low-K+ solution or to a stimulator of Na+-K+ pumping, aldosterone. Ouabain and low K+ depressed the response to hypoxia but had little effect on that to angiotensin II. The response to KCl was increased by ouabain. Aldosterone potentiated the hypoxic response. These results do not support the idea that membrane depolarization due to inhibition Na+-K+ pumping is a component of hypoxic vasoconstriction. They do suggest a positive relationship between Na+-K+-ATPase activity and hypoxic pressor reactivity and are consistent with the idea that Na+-K+-ATPase activity might influence hypoxic reactivity indirectly by altering cellular energy metabolism. It is also possible that the results were somehow due to changes in intracellular [Na+] or transmembrane Na+ gradient, rather than to changes in energy metabolism.

Does leukotriene C4 mediate hypoxic vasoconstriction in isolated ferret lungs?

1990 ◽  
Vol 68 (1) ◽  
pp. 253-259 ◽  
Author(s):  
C. M. Tseng ◽  
M. McGeady ◽  
T. Privett ◽  
A. Dunn ◽  
J. T. Sylvester
Keyword(s):  
Pulmonary Arterial Pressure ◽  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Physiological Salt Solution ◽  
Leukotriene C4 ◽  
Prostaglandin F2 Alpha ◽  
Pulmonary Vasoconstriction ◽  
Vasoconstrictor Response ◽  
Hypoxic Vasoconstriction ◽  
Pulmonary Arterial

To evaluate leukotriene (LT) C4 as a mediator of hypoxic pulmonary vasoconstriction, we examined the effects of FPL55712, a putative LT antagonist, and indomethacin, a cyclooxygenase inhibitor, on vasopressor responses to LTC4 and hypoxia (inspired O2 tension = 25 Torr) in isolated ferret lungs perfused with a constant flow (50 ml.kg-1.min-1). Pulmonary arterial injections of LTC4 caused dose-related increases in pulmonary arterial pressure during perfusion with physiological salt solution containing Ficoll (4 g/dl). FPL55712 caused concentration-related inhibition of the pressor response to LTC4 (0.6 micrograms). Although 10 micrograms/ml FPL55712 inhibited the LTC4 pressor response by 61%, it did not alter the response to hypoxia. At 100 microgram/ml, FPL55712 inhibited the responses to LTC4 and hypoxia by 73 and 71%, respectively, but also attenuated the vasoconstrictor responses to prostaglandin F2 alpha (78% at 8 micrograms), phenylephrine (68% at 100 micrograms), and KCl (51% at 40 mM). At 0.5 microgram/ml, indomethacin significantly attenuated the pressor response to arachidonic acid but did not alter responses to LTC4 or hypoxia. These results suggest that in isolated ferret lungs 1) the vasoconstrictor response to LTC4 did not depend on release of cyclooxygenase products and 2) LTC4 did not mediate hypoxic vasoconstriction.

Prostaglandin synthetase inhibitors do not decrease hypoxic pulmonary vasoconstriction

1976 ◽  
Vol 41 (5) ◽  
pp. 714-718 ◽  
Author(s):  
E. K. Weir ◽  
I. F. McMurtry ◽  
A. Tucker ◽  
J. T. Reeves ◽  
R. F. Grover
Keyword(s):  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Prostaglandin Synthesis ◽  
Pulmonary Vasoconstriction ◽  
Pressor Responses ◽  
Hypoxic Vasoconstriction ◽  
Before And After ◽  
Anesthetized Dogs ◽  
Prostaglandin Antagonists ◽  
The Stability

Prostaglandins are naturally occurring substances with powerful vasoactive effects that are released from tissues during hypoxia or ischemia. Several workers have suggested that a prostaglandin may help to mediate the pulmonary vascular pressor response to alveolar hypoxia. To investigate this possibility, we have measured the pressor responses to hypoxia before and after prostaglandin synthesis antagonism with meclofenamate in eight anesthetized dogs, two groups of awake calves (n=10 and =5), and nine isolated, perfused rat lungs. In addition, synthesis was inhibited by the use of indomethacin in nine additional dogs. The stability of the pulmonary vascular response to repeated hypoxic challenges was demonstrated in nine other dogs. In each species and with both prostaglandin antagonists, the pulmonary pressorresponses to hypoxia were significantly increased rather than reduced. We conclude that prostaglandins do not mediate the pulmonary vasoconstriction caused by hypoxia. The consistent increase observed suggests that hypoxic vasoconstriction stimulates prostaglandin synthesis, the net effect of which is pulmonary vasodilatation which opposes the constriction.

Metabolic and respiratory hydrogen ion effects on hypoxic pulmonary vasoconstriction

1984 ◽  
Vol 57 (2) ◽  
pp. 545-550 ◽  
Author(s):  
C. Marshall ◽  
L. Lindgren ◽  
B. E. Marshall
Keyword(s):  
Pressor Response ◽  
Hypoxic Pulmonary Vasoconstriction ◽  
Respiratory Acidosis ◽  
Hydrogen Ion ◽  
Regression Equations ◽  
Rat Lung ◽  
Pulmonary Vasoconstriction ◽  
Pressor Responses ◽  
Ion Effects

Hypoxic pulmonary vasoconstriction (HPV) was studied in the ventilated-perfused rat lung in vitro. Respiratory acidosis and alkalosis were obtained by ventilating with 2, 7, or 10% CO2 (21% O2-balance N2). Metabolic acidosis and alkalosis were produced by the addition of 0.9 N NaHCO3 or 1 N lactic acid to the perfusate at constant PCO2. At each pH the pressor responses to 2 and 4% O2 were compared with the maximum pressor response (R%max) obtained with zero O2 and 5% CO2 at a normal pH (approximately 7.35). HPV was maximal when the [H+] was between 38 and 50 nM and was attenuated by changes of pH in either direction. Both respiratory and metabolic pH changes had similar effects. The combined linear regression equations were as follows: with 2% O2 the response to acidosis was R%max = 101.37 – 0.52 [H+] and to alkalosis was R%max = 2.03 [H+] - 3.85; with 4% O2 the response to acidosis was R%max = 56.88 – 0.3 [H+] and to alkalosis was R%max = 1.16 [H+] - 4.95. These effects were not due to changes of ionized calcium.

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