Sphingosine-1-phosphate effects on guinea pig atrial myocytes: Alterations in action potentials and K+ currents

摘要

Objective Sphingosine-1-phosphate (S-1-P), a potent lysophospholipid mediator which is released from platelets during clotting, activates a G-protein-gated inwardly rectifying K+ current (GIRK) in atrial and sino-atrial node myocytes. We denote this current I_K(S-1-P). A similar GIRK, which is activated by acetylcholine (ACh) and denoted I_K(ACh), is expressed in atrium. It shortens the action potential duration (APD) and reduces the effective refractory period (ERP). We have examined the effect of S-1-P on APD in guinea pig atrial myocytes by characterizing the rectification properties of I_K(S-1-P) and evaluating whether I_K(S-1-P) and I_K(ACh) exhibit convergence/occlusion.