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


METHODS
Single myocytes were dissociated by enzymatic dissociation method. INa was recorded using whole-cell patch-clamp technique.


RESULTS
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.


CONCLUSIONS
AP-Q has a stimulating effect on I(Na) with slowing the inactivation course of INa.
Fu
L Y
LY
Department of Pharmacology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China. flying1515@yahoo.com.
Li
Y
Y
Cheng
L
L
Zhou
H Y
HY
Yao
W X
WX
Xia
G J
GJ
Jiang
M X
MX
D000818:Animals; D004594:Electrophysiology; D005260:Female; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D008387:Marine Toxins / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology*; D012615:Sea Anemones / Q000737:chemistry*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*
D036341:Intercellular Signaling Peptides and Proteins; D008387:Marine Toxins; D010455:Peptides; D015222:Sodium Channels; C012746:anthopleurin-A