Electrophysiological characterization of BmK M1, an alpha-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 martens i Karsch, on voltage-gated Na+ channels. Using the voltage clamp technique, rye assessed the BmK M1 activity on the cardiac Na+ channel (hIII) functio nally expressed in Xenopus oocytes, The main actions of the toxin are a con centration-dependent slowing of the inactivation process and a hyperpolariz ing shift of the steady-state inactivation. This work is the first electrop hysiological characterization of BmK M1 on a cloned Na+ channel, demonstrat ing that this toxin belongs to the class of scorpion alpha -toxins. Our res ults also show that BmK M1 can be considered as a cardiotoxin. (C) 2001 Fed eration of European Biochemical Societies. Published by Elsevier Science B, V, All rights reserved.