title: P2 receptors in human heart: upregulation of P2X6 in patients undergoing heart transplantation, interaction with TNFalpha and potential role in myocardial cell death.
abstract: ATP acts as a neurotransmitter via seven P2X receptor-channels for Na(+) and Ca(2+), and eight G-protein-coupled P2Y receptors. Despite evidence suggesting roles in human heart, the map of myocardial P2 receptors is incomplete, and their involvement in chronic heart failure (CHF) has never received adequate attention. In left myocardia from five to nine control and 5-12 CHF subjects undergoing heart transplantation, we analyzed the full repertoire of P2 receptors and of 10 "orphan" P2Y-like receptors. All known P2Y receptors (i.e. P2Y(1,2,4,6,11,12,13,14)) and two P2Y-like receptors (GPR91 and GPR17) were detected in all subjects. All known P2X(1-7) receptors were also detected; of these, only P2X(6) was upregulated in CHF, as confirmed by quantitative real time-PCR. The potential significance of this change was studied in primary cardiac fibroblasts freshly isolated from young pigs. Exposure of cardiac fibroblasts to ATP or its hydrolysis-resistant-analog benzoylATP induced apoptosis. TNFalpha (a cytokine implicated in CHF progression) exacerbated cell death. Similar effects were induced by ATP and TNFalpha in a murine cardiomyocytic cell line. In cardiac fibroblasts, TNFalpha inhibited the downregulation of P2X(6) mRNA associated to prolonged agonist exposure, suggesting that, by preventing ATP-induced P2X(6) desensitization, TNFalpha may abolish a defense mechanism meant at avoiding Ca(2+) overload and, ultimately, Ca(2+)-dependent cell death. This may provide a basis for P2X(6) upregulation in CHF. In conclusion, we provide the first characterization of P2 receptors in the human heart and suggest that the interaction between TNFalpha and the upregulated P2X(6) receptor may represent a novel pathogenic mechanism in CHF.
authors.affiliation: Department of Pharmacological Sciences, University of Milan, Via Balzaretti 9, 20133 Milan, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Banfi
authors.forename: Silvia
authors.initials: S
authors.lastname: Ferrario
authors.forename: Ombretta
authors.initials: O
authors.lastname: De Vincenti
authors.forename: Stefania
authors.initials: S
authors.lastname: Ceruti
authors.forename: Marta
authors.initials: M
authors.lastname: Fumagalli
authors.forename: Alessia
authors.initials: A
authors.lastname: Mazzola
authors.forename: Nadia
authors.initials: N
authors.lastname: D' Ambrosi
authors.forename: Cinzia
authors.initials: C
authors.lastname: Volontè
authors.forename: Pasquale
authors.initials: P
authors.lastname: Fratto
authors.forename: Ettore
authors.initials: E
authors.lastname: Vitali
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Burnstock
authors.forename: Elena
authors.initials: E
authors.lastname: Beltrami
authors.forename: Alessandro
authors.initials: A
authors.lastname: Parolari
authors.forename: GianLuca
authors.initials: G
authors.lastname: Polvani
authors.forename: Paolo
authors.initials: P
authors.lastname: Biglioli
authors.forename: Elena
authors.initials: E
authors.lastname: Tremoli
authors.forename: Maria P
authors.initials: MP
authors.lastname: Abbracchio
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects*; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000096:biosynthesis*; D013552:Swine; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D014409:Tumor Necrosis Factor-alpha; C110590:purinoceptor P2X6; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000255:Adenosine Triphosphate; D002118:Calcium