Acta Pharmacologica Sinica 2001-12-01

Effect of sea anemone toxin anthopleurin-Q on sodium current in guinea pig ventricular myocytes.

L Y Fu, Y Li, L Cheng, H Y Zhou, W X Yao, G J Xia, M X Jiang

Index: Acta Pharmacol. Sin. 22(12) , 1107-12, (2001)

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Abstract

To investigate the effects of a sea anemone toxin anthopleurin-Q (AP-Q) isolated from Anthopleura xanthogrammica on sodium current (INa) in isolated guinea pig ventricular myocytes.Single myocytes were dissociated by enzymatic dissociation method. INa was recorded using whole-cell patch-clamp technique.AP-Q (3 - 300 nmol/L) increased INa in a concentration-dependent manner. The EC50 value for increasing INa was 104 nmol/L (95 % confidence range: 78 - 130 nmol/L). AP-Q 300 nmol/L shifted the I-V curve to the leftward, changed the membrane potential of half maximal activation to more negative potential from (-36.3 +/- 2.3) mV to (-43 +/- 3) mV (n = 6, P < 0.01) and changed the membrane potential of half maximal inactivation to more positive potential from (-75 +/- 6) mV to (-59 +/- 5) mV (n = 6, P < 0.01). AP-Q 300 nmol/L shortened the half-recovery time of INa from (114 +/- 36) ms to (17 +/- 2) ms (n = 6, P < 0.01). The fast inactivation time constant (tauf) of INa was markedly increased by AP-Q 300 nmol/L.AP-Q has a stimulating effect on I(Na) with slowing the inactivation course of INa.