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Abstract
It has been known for more than 60 years, and suspected for over 100, that alveolar hypoxia causes pulmonary vasoconstriction by means of mechanisms local to the lung. For the last 20 years, it has been clear that the essential sensor, transduction, and effector mechanisms responsible for hypoxic pulmonary vasoconstriction (HPV) reside in the pulmonary arterial smooth muscle cell. The main focus of this review is the cellular and molecular work performed to clarify these intrinsic mechanisms and to determine how they are facilitated and inhibited by the extrinsic influences of other cells. Because the interaction of intrinsic and extrinsic mechanisms is likely to shape expression of HPV in vivo, we relate results obtained in cells to HPV in more intact preparations, such as intact and isolated lungs and isolated pulmonary vessels. Finally, we evaluate evidence regarding the contribution of HPV to the physiological and pathophysiological processes involved in the transition from fetal to neonatal life, pulmonary gas exchange, high-altitude pulmonary edema, and pulmonary hypertension. Although understanding of HPV has advanced significantly, major areas of ignorance and uncertainty await resolution.
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Affiliation(s)
- J. T. Sylvester
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Larissa A. Shimoda
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Philip I. Aaronson
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
| | - Jeremy P. T. Ward
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland; and Division of Asthma, Allergy and Lung Biology, School of Medicine, King's College, London, United Kingdom
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Morio Y, Homma N, Takahashi H, Yamamoto A, Nagaoka T, Sato K, Muramatsu M, Fukuchi Y. Activity of endothelium-derived hyperpolarizing factor is augmented in monocrotaline-induced pulmonary hypertension of rat lungs. J Vasc Res 2007; 44:325-35. [PMID: 17438361 DOI: 10.1159/000101778] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Accepted: 02/18/2007] [Indexed: 11/19/2022] Open
Abstract
The mechanism of endothelium-dependent vasodilator signaling involves three components such as nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor (EDHF). Although EDHF is distinct from nitric oxide and prostacyclin, it requires activation of Ca(2+)-sensitive K(+) channels (K(Ca)) and cytochrome P(450) metabolites. However, the physiological role of EDHF in the pulmonary circulation is unclear. Thus, we tested if EDHF would regulate vascular tone in rat lungs of control and monocrotaline (MCT)-induced pulmonary hypertension. Inhibition of EDHF with a combination of K(Ca) blockers, charybdotoxin (50 nM) plus apamin (50 nM), increased baseline vascular tone in MCT-induced hypertensive lungs. Thapsigargin (TG; 100 nM), an inhibitor of Ca-ATPase, caused greater EDHF-mediated vasodilation in MCT-induced hypertensive lungs. TG-induced vasodilation was abolished with the charybdotoxin-apamin combination. Sulfaphenazole (10 muM), a cytochrome P(450) inhibitor, reduced the TG-induced vasodilation in MCT-induced hypertensive lungs. RT-PCR analysis exhibited an increase in K(Ca) mRNA in MCT-treated lungs. These results indicate the augmentation of tonic EDHF activity, at least in part, through the alteration in cytochrome P(450) metabolites and the upregulation of K(Ca) expression in MCT-induced pulmonary hypertension.
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MESH Headings
- Animals
- Anti-Infective Agents/pharmacology
- Apamin/pharmacology
- Biological Factors/metabolism
- Charybdotoxin/pharmacology
- Cyclic GMP/metabolism
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Enzyme Inhibitors/pharmacology
- Epoprostenol/metabolism
- Hypertension, Pulmonary/chemically induced
- Hypertension, Pulmonary/metabolism
- Hypertension, Pulmonary/pathology
- Hypertrophy, Right Ventricular/chemically induced
- Hypertrophy, Right Ventricular/metabolism
- Hypertrophy, Right Ventricular/pathology
- Male
- Monocrotaline/toxicity
- Neurotoxins/pharmacology
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/metabolism
- Potassium Channels, Calcium-Activated/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Sprague-Dawley
- Sulfaphenazole/pharmacology
- Thapsigargin/pharmacology
- Vascular Cell Adhesion Molecule-1/metabolism
- Vasodilation/drug effects
- Vasodilation/physiology
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Affiliation(s)
- Yoshiteru Morio
- Department of Respiratory Medicine, Juntendo University School of Medicine, Tokyo, Japan.
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