title: Prostacyclin receptor-mediated ATP release from erythrocytes requires the voltage-dependent anion channel.
abstract: Erythrocytes have been implicated as controllers of vascular caliber by virtue of their ability to release the vasodilator ATP in response to local physiological and pharmacological stimuli. The regulated release of ATP from erythrocytes requires activation of a signaling pathway involving G proteins (G(i) or G(s)), adenylyl cyclase, protein kinase A, and the cystic fibrosis transmembrane conductance regulator as well as a final conduit through which this highly charged anion exits the cell. Although pannexin 1 has been shown to be the final conduit for ATP release from human erythrocytes in response to reduced oxygen tension, it does not participate in transport of ATP following stimulation of the prostacyclin (IP) receptor in these cells, which suggests that an additional protein must be involved. Using antibodies directed against voltage-dependent anion channel (VDAC)1, we confirm that this protein is present in human erythrocyte membranes. To address the role of VDAC in ATP release, two structurally dissimilar VDAC inhibitors, Bcl-x(L) BH4(4-23) and TRO19622, were used. In response to the IP receptor agonists, iloprost and UT-15C, ATP release was inhibited by both VDAC inhibitors although neither iloprost-induced cAMP accumulation nor total intracellular ATP concentration were altered. Together, these findings support the hypothesis that VDAC is the ATP conduit in the IP receptor-mediated signaling pathway in human erythrocytes. In addition, neither the pannexin inhibitor carbenoxolone nor Bcl-x(L) BH4(4-23) attenuated ATP release in response to incubation of erythrocytes with the β-adrenergic receptor agonist isoproterenol, suggesting the presence of yet another channel for ATP release from human erythrocytes.
authors.affiliation: Department of Pharmacological and Physiological Science, Saint Louis University School of Medicine, Saint Louis, Missouri, MO 63104, USA. meerasrid@gmail.com
authors.forename: Meera
authors.initials: M
authors.lastname: Sridharan
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Bowles
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Richards
authors.forename: Medina
authors.initials: M
authors.lastname: Krantic
authors.forename: Katie L
authors.initials: KL
authors.lastname: Davis
authors.forename: Kristine A
authors.initials: KA
authors.lastname: Dietrich
authors.forename: Alan H
authors.initials: AH
authors.lastname: Stephenson
authors.forename: Mary L
authors.initials: ML
authors.lastname: Ellsworth
authors.forename: Randy S
authors.initials: RS
authors.lastname: Sprague
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000328:Adult; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D002229:Carbenoxolone / Q000494:pharmacology; D017630:Connexins / Q000037:antagonists & inhibitors / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D011464:Epoprostenol / Q000031:analogs & derivatives / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D006801:Humans; D016285:Iloprost / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology; D050995:Voltage-Dependent Anion Channel 1 / Q000378:metabolism*; D055815:Young Adult; D051020:bcl-X Protein / Q000494:pharmacology
chemical_list: D000318:Adrenergic beta-Agonists; D000959:Antihypertensive Agents; C494811:BCL2L1 protein, human; D017630:Connexins; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; C113936:PTGIR protein, human; D044006:Receptors, Epoprostenol; D011982:Receptors, Prostaglandin; C494762:VDAC1 protein, human; D014665:Vasodilator Agents; D051020:bcl-X Protein; D000255:Adenosine Triphosphate; D011464:Epoprostenol; D000242:Cyclic AMP; D050995:Voltage-Dependent Anion Channel 1; D016285:Iloprost; D007545:Isoproterenol; D002229:Carbenoxolone; C427248:treprostinil