Chronic hypoxia impairs extracellular nucleotide metabolism and barrier function in pulmonary artery vasa vasorum endothelial cells

MediCity Research Laboratory, University of Turku and National Institute of Health and Welfare, Tykistökatu 6A, 20520, Turku, Finland.
Angiogenesis (Impact Factor: 4.88). 09/2011; 14(4):503-13. DOI: 10.1007/s10456-011-9234-0
Source: PubMed


Vascular remodeling plays a pivotal role in a variety of pathophysiological conditions where hypoxia and inflammation are prominent features. Intravascular ATP, ADP and adenosine are known as important regulators of vascular tone, permeability and homeostasis, however contribution of purinergic signalling to endothelial cell growth and angiogenesis remains poorly understood. By using vasa vasorum endothelial cells (VVEC) isolated from pulmonary artery adventitia of control and chronically hypoxic neonatal calves, these studies were aimed to evaluate the effect of hypoxia on biochemical and functional properties of microvascular endothelial network at the sites of angiogenesis. In comparison with normoxic controls, VVEC from hypoxic animals are characterized by (1) drastically impaired nucleoside triphosphate diphosphohydrolase-1 (NTPDase-1/CD39) and ecto-5'-nucleotidase/CD73 activities with respective increases in basal extracellular ATP and ADP levels (2) higher proliferative responses to low micromolar concentrations of ATP and ADP; and (3) enhanced permeability and disordered adenosinergic control of vascular barrier function (measured as a paracellular flux of 70 kDa fluorescein isothiocyanate-dextran). Together, these results suggest that unique pattern of purine-mediated angiogenic activation and enhanced leakiness of VVEC from chronically hypoxic vessels may be defined by disordered endothelial nucleotide homeostasis at sites of active neovascularization.

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Available from: Evgenia V Gerasimovskaya
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    • "yruvate kinase and phosphoenol pyruvate ( Sorensen et al . , 2003 ) or myokinase ( adenylate kinase ) preparation ( Strehler & Totter , 1952 ) , followed by bioluminescent detection of ADP - derived ATP . Using these techniques , extracellular ADP levels were determined in cultured endothelial , lymphoid and tumor cells ( Helenius et al . , 2012 ; Yegutkin et al . , 2011a ) , rat pancreatic juice ( Sorensen et al . , 2003 ) , keratino - cytes ( Mizumoto et al . , 2002 ) , murine plasma ( Enjyoji et al . , 1999 ; Mercier et al . , 2012 ) , and human vitreous fluids ( Loukovaara et al . , 2014 ) . Likewise , using another mixture of enzymes and substrates , another important ATP metabolite , PP i , can be "
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    ABSTRACT: Abstract Extracellular nucleotides and nucleosides mediate diverse signaling effects in virtually all organs and tissues. Most models of purinergic signaling depend on functional interactions between distinct processes, including (i) the release of endogenous ATP and other nucleotides, (ii) triggering of signaling events via a series of nucleotide-selective ligand-gated P2X and metabotropic P2Y receptors as well as adenosine receptors and (iii) ectoenzymatic interconversion of purinergic agonists. The duration and magnitude of purinergic signaling is governed by a network of ectoenzymes, including the enzymes of the nucleoside triphosphate diphosphohydrolase (NTPDase) family, the nucleotide pyrophosphatase/phosphodiesterase (NPP) family, ecto-5'-nucleotidase/CD73, tissue-nonspecific alkaline phosphatase (TNAP), prostatic acid phosphatase (PAP) and other alkaline and acid phosphatases, adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP). Along with "classical" inactivating ectoenzymes, recent data provide evidence for the co-existence of a counteracting ATP-regenerating pathway comprising the enzymes of the adenylate kinase (AK) and nucleoside diphosphate kinase (NDPK/NME/NM23) families and ATP synthase. This review describes recent advances in this field, with special emphasis on purine-converting ectoenzymes as a complex and integrated network regulating purinergic signaling in such (patho)physiological states as immunomodulation, inflammation, tumorigenesis, arterial calcification and other diseases. The second part of this review provides a comprehensive overview and basic principles of major approaches employed for studying purinergic activities, including spectrophotometric Pi-liberating assays, high-performance liquid chromatographic (HPLC) and thin-layer chromatographic (TLC) analyses of purine substrates and metabolites, capillary electrophoresis, bioluminescent, fluorometric and electrochemical enzyme-coupled assays, histochemical staining, and further emphasizes their advantages, drawbacks and suitability for assaying a particular catalytic reaction.
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    • "By regulating extracellular nucleotide levels, NTPDase1 affects haemostasis [12, 13, 37], leukocyte migration [24, 25], immune responses [6, 49], angiogenesis, vascular permeability [17, 50], and vasoconstriction [8, 15]. Therefore the identification of selective NTPDase1 inhibitors would be valuable tools to study the function and pathological consequence of dysregulation of NTPDase1 activity. "
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    • "In the coronary vascular bed, ENTPD1 (CD39) [7,8] and CD73 [9] are thought to be involved in the conversion of ATP to Ado. Recent studies suggested that ectonucleotidase activity is altered under pathophysiological conditions of the heart, such as myocardial ischemia and chronic heart failure [10-13]. Activation of CD73 was found in the preconditioned heart, which was induced by brief periods of myocardial ischemia [11]. "
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