title: Paracrine purinergic signaling determines lung endothelial nitric oxide production.
abstract: Although the vascular bed is a major source of nitric oxide (NO) production, factors regulating the production remain unclear. We considered the role played by paracrine signaling. Determinations by fluorescence microscopy in isolated, blood-perfused rat and mouse lungs revealed that a brief lung expansion enhanced cytosolic Ca(2+) (Ca(2+)cyt) oscillations in alveolar epithelial (AEC) and endothelial (EC) cells, and NO production in EC. Furthermore, as assessed by a novel microlavage assay, alveolar ATP production increased. Intra-alveolar microinfusion of the purinergic receptor antagonist, PPADS, and the nucleotide hydrolyzing enzyme, apyrase, each completely blocked the Ca(2+)cyt and NO responses in EC. Lung expansion induced Ca(2+)cyt oscillations in mice lacking the P2Y1, but not the P2Y2, purinergic receptors, which were located in the perivascular interstitium basolateral to AEC. Prolonged lung expansion instituted by mechanical ventilation at high tidal volume increased EC expression of nitrotyrosine, indicating development of nitrosative stress in lung microvessels. These findings reveal a novel mechanism in which mechanically induced purinergic signaling couples cross-compartmental Ca(2+)cyt oscillations to microvascular NO production.
authors.affiliation: Lung Biology Laboratory, Department of Medicine, College of Physicians and Surgeons, Columbia University, St. Luke's-Roosevelt Hospital Center, New York, New York, USA.
authors.forename: Rainer
authors.initials: R
authors.lastname: Kiefmann
authors.forename: Mohammad N
authors.initials: MN
authors.lastname: Islam
authors.forename: Jens
authors.initials: J
authors.lastname: Lindert
authors.forename: Kaushik
authors.initials: K
authors.lastname: Parthasarathi
authors.forename: Jahar
authors.initials: J
authors.lastname: Bhattacharya
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008833:Microcirculation / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019899:Paracrine Communication / Q000502:physiology*; D011650:Pulmonary Alveoli / Q000098:blood supply / Q000201:enzymology*; D011652:Pulmonary Circulation / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: C546383:P2ry1 protein, mouse; C546384:P2ry1 protein, rat; C546386:P2ry2 protein, mouse; C546387:P2ry2 protein, rat; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat