Pharmacological characterization of a UTP-sensitive P2Y nucleotide receptor in organ cultured coronary arteries.
Our lab has previously demonstrated that organ cultured coronary smooth muscle cells express a nucleotide receptor that is dramatically more responsive to UTP than non-organ cultured cells. Thus, the purpose of this study was to pharmacologically characterize this UTP-sensitive nucleotide receptor. Porcine coronary arteries were organ cultured (serum-free media, 37 degrees C) for 4 days, and fura-2 imaging of single cells was used to measure myoplasmic Ca2+ (Cam) in response to several nucleotide agonists. A concentration-response relationship (0.01-100 microM) was generated to the nucleotide receptor agonists, UTP, UDP, ATP, ADP, and 2-MeSATP. The potency order was UTP >> UDP = ATP = ADP = 2-MeSATP, thus, this nucleotide receptor is predominantly UTP-sensitive. The Cam response to 10 microM UTP was attenuated approximately 50% by the nucleotide receptor antagonists (10 and 100 microM), suramin, reactive blue 2, and pyridoxalphosphate-6-azophenyl-2',4'-disulphonoic acid (PPADS). Depletion of the sarcoplasmic reticulum Ca2+ store with thapsigargin completely abolished the UTP-induced Cam response. In addition, the peak UTP-induced Cam increase was almost two-fold higher in a 2-mM Ca2+ solution than a 0-mM Ca2+ solution. This suggests that the UTP-induced Cam response is comprised of both Ca2+ influx and the mobilization of intracellular Ca2+ stores. Pertussis toxin reduced the UTP-induced Cam response 50%, thus, the UTP-induced increase in Cam is mediated, in part, via Gi/o. These data suggest this UTP-sensitive receptor belongs to the P2Y nucleotide receptor family; however, it does not possess pharmacological characteristics associated with any known P2Y receptor subtype.
Hill
Brent J F
BJ
Department of Physiology, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
Sturek
Michael
M
D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology; D009924:Organ Culture Techniques; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2 / Q000502:physiology; D013552:Swine; D014544:Uridine Triphosphate / Q000494:pharmacology*
D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D014544:Uridine Triphosphate