Electrophysiological characterization of BmK M1, an α‐like toxin from Buthus martensi Karsch venom

Abstract
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.