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

The present study investigates the electrophysiological actions of BmK M1, an alpha -like toxin purified from the venom of the scorpion Buthus martensi Karsch, on voltage-gated Na+ channels. Using the voltage clamp technique, rye assessed the BmK M1 activity on the cardiac Na+ channel (hIII) 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 alpha -toxins. Our results also show that BmK M1 can be considered as a cardiotoxin. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B,V, All rights reserved.