Endogenous diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate in human myocardial tissue.
Diadenosine polyphosphates have been characterized as extracellular mediators controlling numerous physiological effects. In this study, diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate were isolated and identified in human myocardial tissue. Human myocardial tissue was homogenized and fractionated by affinity chromatography, displacement chromatography, anion-exchange chromatography, and reversed-phase chromatography. In fractions purified to homogeneity, diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate were revealed by matrix-assisted laser desorption/ionization mass spectrometry and ultraviolet spectroscopy. These diadenosine polyphosphates were further identified by enzymatic analysis, which demonstrated an interconnection of the phosphate groups with the adenosines in the 5' positions of the riboses. Furthermore, diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate were found in human cardiac-specific granules, and the amount of diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate was estimated in the range of approximately 500 micromol/L. In conclusion, the experiments show that the diadenosine polyphosphates with 2 and 3 phosphate groups occur in human myocardial tissue, and so do the diadenosine polyphosphates with 4 to 6 phosphate groups. After being released by cholinergic stimulation, which is known to affect diadenosine polyphosphate release from secretory granules, diadenosine tetraphosphate, diadenosine pentaphosphate, and diadenosine hexaphosphate activate P2X purinoceptors in vascular smooth muscle; hence, they can act as vasoconstrictors. It may be inferred that the differential action of both predominantly vasodilator and vasoconstrictor diadenosine polyphosphates allow a fine-tuning of myocardial blood flow by locally released diadenosine polyphosphates.
Luo
Jiankai
J
Medizinische Klinik IV, Charite-Campus Benjamin Franklin, Berlin, Germany.
Jankowski
Vera
V
Güngär
Nihayrt
N
Neumann
Joachim
J
Schmitz
Wilhelm
W
Zidek
Walter
W
Schlüter
Hartmut
H
Jankowski
Joachim
J
D018678:Cholinergic Agents / Q000494:pharmacology; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D015226:Dinucleoside Phosphates / Q000032:analysis* / Q000502:physiology; D006321:Heart / Q000187:drug effects / Q000502:physiology; D006801:Humans; D009206:Myocardium / Q000737:chemistry*; D015221:Potassium Channels / Q000502:physiology; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D058469:Receptors, Purinergic P2X; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013056:Spectrophotometry, Ultraviolet; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology
D018678:Cholinergic Agents; D015226:Dinucleoside Phosphates; D015221:Potassium Channels; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; C012275:P(1),P(5)-di(adenosine-5'-)pentaphosphate; C020733:diadenosine tetraphosphate; C070070:diadenosine 5',5''''-P1,P6-hexaphosphate