Pentoxifylline Rescue Preserves Lung Function in Isolated Canine Lungs Injured With Phorbol Myristate Acetate

doi:10.1378/chest.119.6.1893

Chest

Volume 119, Issue 6, June 2001, Pages 1893-1900

https://doi.org/10.1378/chest.119.6.1893 Get rights and content

Objective

We hypothesized that pentoxifylline, administered after phorbol myristate acetate (PMA), would diminish the severity of lung injury.

Setting

Animal research laboratory.

Design

Comparative study.

Subjects

Mongrel dogs (n = 33).

Interventions

Baseline measurements were obtained from the isolated blood-perfused dog lung lobes after 1 h of stable perfusion and ventilation. Four different measures of lung compliance were obtained along with WBC and neutrophil counts. Pulmonary vascular resistance (PVR) and capillary filtration coefficient (Kf) were calculated, and the ratio of a normalized maximal enzymatic conversion rate to the Michaelis-Menten constant (Amax/Km) was used to assess perfused capillary surface area. The control lobes (n = 8) were ventilated and perfused for an additional 40 min while the injured lobes (n = 17) received PMA (0.1 μg/mL of perfusate). The pentoxifylline-protected lobes (n = 8) were treated with pentoxifylline (1 mg/mL of perfusate) 10 min after injury with PMA. All measurements were then repeated.

Measurement and main results

The three groups did not differ significantly at baseline. The control lobes remained relatively stable over time. The injured lobes demonstrated marked deterioration in compliance: 8.79 ± 0.7 to 5.97 ± 0.59 mL/cm H₂O (p < 0.05) vs 10.1 ± 1.0 to 8.07 ± 0.72 mL/cm H₂O and 9.6 ± 1.1 to 9.9 ± 0.85 mL/cm H₂O in the control and protected lobes, respectively. Both groups receiving PMA had similar drops in WBC and neutrophil counts, but the pentoxifylline-protected lobes had preservation of all four compliance measures. PVR increased from 37.8 ± 1.8 to 118.6 ± 12.7 cm H₂O/L/min (p < 0.05) in the injured lobes vs 35.4 ± 0.5 to 36.3 ± 2.8 cm H₂O/L/min and 40.4 ± 0.04 to 46.7 ± 2.8 cm H₂O/L/min (p < 0.05) in the control and protected lobes, respectively. Kf increased < 25% in the protected group but more than tripled in the injured group. Amax/Km dropped from 559 ± 36 to 441 ± 33 mL/min (p < 0.05) in the injured lobes vs 507 ± 14 to 490 ± 17 mL/min and 609 ± 34 to 616 ± 37 mL/min in the control and pentoxifylline-protected lobes, respectively.

Conclusions

The use of pentoxifylline as a rescue agent prevented the PMA-induced deterioration of lung compliance, vascular integrity, and endothelial metabolic function in this acute lung injury model, despite significant pulmonary neutrophil sequestration.

Section snippets

Isolated Lung Lobe Preparation

We used mongrel dogs weighing 20.7 ± 0.33 kg (mean ±SD). Investigators complied with national standards regarding care and use of laboratory animals. The facilities were fully accredited by the Association for the Assessment and Accreditation of Laboratory Animal Care, International. They were anesthetized with 30 mg/kg of IV pentobarbital sodium (Abbott Laboratories; North Chicago IL). They were then intubated and received mechanical ventilation (rate, 10 to 15 breaths/min; tidal volume [Vt],

Results

The groups were not different from each other in baseline dog weight (20.7 ± 0.33 kg), lobe weight (39.9 ± 1.23 g), Vt used (55.5 ± 0.72 mL), or PEEP (4.4 ± 0.11 cm H₂O) settings. Initial measures of compliance were also similar, with opening pressure (10.9 ± 0.36 cm H₂O), closing pressure (2.8 ± 0.29 cm H₂O), static compliance (19.1 ± 0.51 mL/cm H₂O), and spot compliance (9.2 ± 0.52 mL/cm H₂O) not significantly differing between groups. Vascular integrity measured by PVR and Kf were also

Discussion

Using the isolated blood-perfused lung preparation allowed us to eliminate many confounding systemic influences. We were able to study endothelial metabolic function in its natural milieu as well as follow WBC trapping since the neutrophils were either in circulation or sequestered in the lung. The simplicity of the system also allowed for easy measure of Kf and lobar weight change. With the addition of compliance measures and estimates of ACE activity, we were able to follow the PMA-induced

ACKNOWLEDGMENT

The authors would like to acknowledge the technical expertise and assistance given by Hiram Ocasio and James Parkerson. We would also like to thank Dr. Cynthia H. Shields who provided invaluable proofreading services.

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Pentoxifylline
2008, xPharm: The Comprehensive Pharmacology Reference
Pentoxifylline is a synthetic dimethylxanthine derivative structurally related to the methylxanthine derivatives theophylline, caffeine, and theobromine. Pentoxifylline differs structurally from these other agents by the presence of a 5-oxohexyl group at position 1.
Pentoxifylline is usually classified as a vasodilator. However, its primary action appears to be a reduction in blood viscosity by increasing erythrocyte deformability, inhibiting platelet adhesion and aggregation, reducing plasma fibrinogen, and increasing fibrinolytic activity. Pentoxifylline is reported to increase blood flow to ischemic tissues and improve tissue oxygenation in patients with peripheral vascular disease. In the central nervous system, pentoxifylline can increase oxygen tension in both the cerebral cortex and in the cerebrospinal fluid. Pentoxifylline has also been shown to increase leukocyte deformability, inhibit neutrophil adhesion and activation and inhibit production of the cytokine, tumor necrosis factor-alpha (TNF).
Pentoxifylline is indicated in the treatment of intermittent claudication associated with peripheral vascular diseases (i.e., chronic occlusive arterial disease of the extremities). Although pentoxifylline can improve function and reduce symptoms of these diseases, it is not intended to replace more definitive treatments, such as surgical bypass or removal of arterial obstructions (Physicians desk reference, 2005).It has also been suggested to be useful in the treatment of many other conditions including acute and chronic cerebrovascular insufficiency associated with ischemic stroke, psychopathological symptoms associated with aging, transient ischemic attacks …
N-acetylcysteine attenuates the acute lung injury caused by phorbol myristate acetate in isolated rat lungs
2007, Pulmonary Pharmacology and Therapeutics
Citation Excerpt :
The reduction of methyl guanidine by NAC may account at least in part, the protective role of NAC on the PMA-ALI. Several studies reported the effectiveness of antioxidants such as dimethythiourea [30], pentoxifylline [10], lipophilic oxidant scavengers U7389G and U74500A [9,13] on the PMA-induced ALI. These results further support the involvement of free radical in the PMA-induced changes and the importance of free radical reduction in the preventive strategy for ALI induced by phorbol.
Acute lung injury (ALI) caused by phorbol myristate acetate (PMA) is characterized by pulmonary edema and inflammatory cells infiltration. PMA-activated neutrophils in vivo and in vitro to release free radicals, pro-inflammatory cytokines, nitric oxide (NO) and other mediators. These mediators may be the causes of pulmonary hypertension and increased microvascular permeability. In the present study, we used isolated perfused rat lungs from Sprague–Dawley (SD) rats. The purpose was to evaluate the effects of pretreatment of N-acetylcysteine (NAC) on the PMA-induced ALI and associated changes.
PMA (2 μg kg⁻¹) was introduced into the lung perfusate. NAC (150 mg kg⁻¹) was administered 10 min before PMA. Thirty isolated lungs were randomly assigned to receive vehicle (dimethyl sulfoxide, DMSO, the solvent for PMA, 100 μg g⁻¹), PMA alone and PMA with NAC pretreatment. There were 10 lungs in each group. We measured the lung weight (LW) to body weight (BW) ratio (LW/BW), LW gain (LWG), exhaled nitric oxide (NO) and protein concentration in bronchoalveolar lavage (PCBAL). The pulmonary arterial pressure (PAP) and microvascular permeability (K_fc) were assessed. The concentration of nitrate/nitrite, methyl guanidine (MG), tumor necrosis factor_α (TNF_α) and interleukin-1_β (IL-1_β) in lung perfusate were determined. In addition, we also evaluate the lung injury by histopathological examination and by grading system for the lung injury score (LIS).
PMA caused severe ALI as evidenced by the marked increases in LW changes, exhaled NO, PCBAL, histopathological changes, and LIS. It also increased the nitrate/nitrite, MG, TNF_α, and IL-1_β in lung perfusate. Pretreatment with NAC significantly attenuated these changes and abrogated the extent of ALI. Our results suggest that NAC exerts strong protective effects on the PMA-induced ALI and associated alterations. The mechanisms are possibly attributable to its antioxidant actions, inhibition of pro-inflammatory cytokines, and restoration of glutathione enzymes.
Novel protection strategy for pulmonary transplantation
2003, Journal of Surgical Research
Background. Ischemia-reperfusion injury continues to represent a significant challenge to successful lung transplantation. Traditional pulmonary ischemic protection is performed using hypothermic hyperkalemic depolarizing solutions to reduce the metabolic demands of the ischemic organ. Measures to further reduce the effects of ischemic injury have focused on the reperfusion period. We tested the hypothesis that novel physiologic hyperpolarizing solutions—using ATP-dependent potassium channel (K_ATP) openers—given at the induction of ischemia, will reduce cellular injury and provide superior graft function even after prolonged periods of ischemia.
Methods. An isolated blood-perfused ventilated rabbit lung model was used to study lung injury. Airway, left atrial, and pulmonary artery pressures were measured continuously during the 2-h reperfusion period. Oxygenation, as a surrogate of graft function, was measured using intermittent blood gas analysis of paired left atrial and pulmonary artery blood samples. Graft function was measured by oxygen challenge technique (F_iO₂ = 1.0). Wet-to-dry ratio was measured at the conclusion of the 2-h reperfusion period. Control (Group I) lungs were perfused with modified Euro-Collins solution (depolarizing) and reperfused immediately (no ischemia). Traditional protection lungs were perfused with modified Euro-Collins flush solution and stored for 4 h (Group II) or 18 h (Group III) at 4°C before reperfusion. Novel protection (Group IV) lungs were protected with a hyperpolarizing solution containing 100 nM Aprikalim, a specific K_ATP channel opener, added to the modified Euro-Collins flush solution and underwent 18 h of ischemic storage at 4°C before reperfusion.
Results. Profound graft failure was measured after 18 h of ischemic storage with traditional protection strategies (Group III). Graft function was preserved by protection with hyperpolarizing solutions even for prolonged ischemic periods (Group IV). Wet-to-dry weight ratio, airway, left atrial, and pulmonary artery pressures were not significantly different between the groups.
Conclusions. We have created a model of predictable lung injury. Membrane hyperpolarization with a K_ATP channel opener (PCO) provides superior prolonged protection from ischemia-reperfusion injury in an in vitro model of pulmonary transplantation.
Niacinamide mitigated the acute lung injury induced by phorbol myristate acetate in isolated rat's lungs
2012, Journal of Biomedical Science
Acute lung injury and acute respiratory distress syndrome: Experimental and clinical investigations
2011, Journal of Geriatric Cardiology
Histomorphologic and respiratory aspects of acute lung injury in rats induced by experimental sepsis and under pentoxifylline treatment
2009, Revista da Associacao Medica Brasileira

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This work was performed at the Vascular Biology Center of the MedicalCollege of Georgia, Augusta, GA, and was supported in part by a grantfrom the Southeastern Affiliate of the American Heart Association.

The views expressed in this article are those of the authorsand do not reflect the official policy or position of the Department of the Army, Department of Defense, or the US Government.

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Chest

Laboratory and Animal InvestigationsPentoxifylline Rescue Preserves Lung Function in Isolated Canine Lungs Injured With Phorbol Myristate Acetate

Objective

Setting

Design

Subjects

Interventions

Measurement and main results

Conclusions

Section snippets

Isolated Lung Lobe Preparation

Results

Discussion

ACKNOWLEDGMENT

Tissue Cell

Respir Physiol

Respir Physiol

Chest

Acute lung injury and the acute respiratory distress syndrome

Crit Care Med

Neutrophil kinetics and lung injury

Physiol Rev

Phorbol myristate acetate: in vivo effects upon neutrophils, platelets, and lung

Am J Pathol

PMA-activated neutrophils decrease pulmonary endothelial ectoenzyme activities in perfused rabbit lungs

Am J Physiol

Acute and progressive lung injury after contact with phorbol myristate acetate

Am J Pathol

Pentoxifylline decreases endotoxin-induced pulmonary neutrophil sequestration and extravascular protein accumulation in the dog

Am Rev Respir Dis

Pentoxifylline reduces injury to isolated lungs perfused with human neutrophils

Am Rev Respir Dis

Cytokines, phagocytes, and pentoxifylline

J Cardiovasc Pharm

Pulmonary endothelial dysfunction in the presence or absence of interstitial injury induced by intratracheally injected bleomycin in rabbits

Am Rev Respir Dis

Lung injury caused by mechanical ventilation

Chest

Tidal ventilation at low airway pressures can augment lung injury

Am J Respir Crit Care Med

Injurious ventilatory strategies increase cytokines and c-fos m-RNA expression in an isolated rat lung model

J Clin Invest

Laboratory and Animal Investigations
Pentoxifylline Rescue Preserves Lung Function in Isolated Canine Lungs Injured With Phorbol Myristate Acetate