Résumé
The present study investigates the electrophysiological actions of
BmK M1, an α-like toxin purified from the venom of the scorpion
Buthus martensi Karsch, on voltage-gated Na
+ channels. Using the voltage clamp technique, we assessed the
BmK M1 activity on the cardiac Na
+ channel (hH1) functionally expressed in
Xenopus oocytes. The main actions of the toxin are a concentration-dependent slowing of the inactivation process and a hyperpolarizing shift of the steady-state inactivation. This work is the first electrophysiological characterization of
BmK M1 on a cloned Na
+ channel, demonstrating that this toxin belongs to the class of scorpion α-toxins. Our results also show that
BmK M1 can be considered as a cardiotoxin.