Uridine triphosphate prolongs action potential duration of guinea pig papillary muscles via P2Y2 purinoceptors
Abstract
Aim: 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.
Conclusion: UTP produced APD prolongation through specific and nonspecific actions, and the specific response to UTP was mediated by P2Y2 purinoceptors.
Keywords:
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.
Conclusion: UTP produced APD prolongation through specific and nonspecific actions, and the specific response to UTP was mediated by P2Y2 purinoceptors.