Effects of sea anemone toxin anthopleurin-Q on potassium currents in rats and guinea pig ventricular myocytes

Objective To investigate the effect of sea anemone toxin anthopleurin-Q (AP-Q) on potassium currents in isolated rats and guinea pig ventricular myocytes. Methods The ventricular cells of guinea pigs and SD rats were obtained by enzymatic dissociation method. Whole cell patch clamp technique was used to record potassium currents (Ito, IK, and IK1). Results AP-Q 3-100 nmol/L increased Ito in a concentration-dependent manner, with an EC50 value of 12.7 nmol/L. At a potential of +50mV, AP-Q 10nmol/L increased Ito from (13.3±3.4) pA pF-1 to (19.46±4.3) pA pF-1. AP-Q 0.1-100 nmol/L increased IK and IK tail in a concentrationdependent manner with EC50 values of 4.7 nmol/L and 5.0 nmol/L, respectively. AP-Q 1 pmol/L-100 nmol/L increased IK1 in dosedependent manner, with an EC50 of 0.2 nmol/L. Conclusions The effect of AP-Q on Ito, IK and IK1 may partly explain its mechanism in shortening APD and increasing RP.