title: Identification and characterization of adenosine 5'-tetraphosphate in human myocardial tissue.
abstract: Endocrine functions of the human heart have been studied extensively. Only recently, nucleotidergic mechanisms have been studied in detail. Therefore, an isolation strategy was developed to isolate novel nucleotide compounds from human myocardium. The human myocardial tissue was fractionated by several chromatographic studies. A substance purified to homogeneity was identified as adenosine 5'-tetraphosphate (Ap(4)) by matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), post-source decay MALDI MS, and enzymatic cleavage analysis. Furthermore, Ap(4) was also identified in ventricular specific granules. In the isolated perfused rat heart, Ap(4) elicited dose-dependent vasodilations. Vasodilator responses were abolished in the presence of the P(2Y1) receptor antagonist MRS 2179 (1 microm) or the NO synthase inhibitor N(G)-nitro-l-arginine methyl ester (50 microm). After removal of the endothelium by Triton X-100, Ap(4) induced dose-dependent vasoconstrictions. Inhibition of P(2X) receptors by pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid (30 microm) or desensitization of P(2X) receptors by alpha,beta-methylene ATP (alpha,beta-meATP, 1 microm) diminished these vasoconstrictor responses completely. In the present study Ap(4) has been isolated from human tissue. Ap(4) was shown to exist in human myocardial tissue and was identified in ventricular specific granules. In coronary vasculature the nucleotide exerted vasodilation via endothelial P(2Y1) receptors and vasoconstriction via P(2X) receptors on vascular smooth muscle cells. Ap(4) acts as an endogenous extracellular mediator and might contribute to the regulation of coronary perfusion.
authors.affiliation: Freie Universität Berlin, Universitätsklinikum Benjamin Franklin, Medizinische Klinik IV, Hindenburgdamm 30, 12200 Berlin, Germany.
authors.forename: Timm
authors.initials: T
authors.lastname: Westhoff
authors.forename: Joachim
authors.initials: J
authors.lastname: Jankowski
authors.forename: Sven
authors.initials: S
authors.lastname: Schmidt
authors.forename: Jiankai
authors.initials: J
authors.lastname: Luo
authors.forename: Günter
authors.initials: G
authors.lastname: Giebing
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schlüter
authors.forename: Martin
authors.initials: M
authors.lastname: Tepel
authors.forename: Walter
authors.initials: W
authors.lastname: Zidek
authors.forename: Markus
authors.initials: M
authors.lastname: van der Giet
mesh_terms: D000227:Adenine Nucleotides / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D003902:Detergents / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000473:pathology; D006801:Humans; D008297:Male; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D017830:Octoxynol / Q000494:pharmacology; D010477:Perfusion; D051381:Rats; D011921:Rats, Inbred WKY; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013552:Swine; D013997:Time Factors; D014466:Ultraviolet Rays; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D003902:Detergents; D014662:Vasoconstrictor Agents; C017991:adenosine 5'-tetraphosphate; D017830:Octoxynol