title: Uridine triphosphate prolongs action potential duration of guinea pig papillary muscles via P2Y2 purinoceptors.
abstract: OBJECTIVE
  To study the electrophysiologic effects of uridine triphosphate (UTP) on the guinea pig papillary muscles in vitro and purinoceptors related with the action of UTP.
  
  
  METHODS
  Intracellular microelectrode method was used to record action potentials (AP) in guinea pig papillary muscles.
  
  
  RESULTS
  UTP, adenosine triphosphate (ATP), and adenosine diphosphate (ADP) prolonged the action potential duration (APD) concentration dependently in guinea pig papillary muscles. The potency order was UTP=ATP > ADP. There was cross desensitization between the response to ATP and that to UTP, and neither Ado nor alpha, beta-MeATP caused great change in AP of the papillary muscles. The prolongation of APD by UTP was not affected by sustained perfusion with aminophylline. As an osmotic pressure control equivalent to UTP 3 mmol/L, ceftriaxonum 3 mmol/L or NaCl 9 mmol/L induced a marked but slight prolongation of APD.
  
  
  CONCLUSIONS
  UTP produced APD prolongation through specific and nonspecific actions, and the specific response to UTP was mediated by P2Y2 purinoceptors.
authors.affiliation: Department of Pharmacology, School of Pharmacy, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: K
authors.initials: K
authors.lastname: Qin
authors.forename: L M
authors.initials: LM
authors.lastname: Ren
authors.forename: D
authors.initials: D
authors.lastname: Zhao
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D014544:Uridine Triphosphate / Q000494:pharmacology*
chemical_list: D058910:Purinergic P2 Receptor Agonists; D018048:Receptors, Purinergic P2; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D014544:Uridine Triphosphate