µ-conotoxin CnIIIC

µ-conotoxin CnIIIC has been isolated from the venom of the marine cone snail Conus consors. µ-conotoxin CnIIICexhibits a myorelaxing effect through specific blockade of the skeletal muscle Na_v1.4 channels (IC₅₀ = 1.4 nM). µ-conotoxin CnIIIC also blocks Na_v1.2 channels (1 µM) and mildly Na_v1.7. In contrast, Na_v1.5 and Na_v1.8 are insensitive to the action of the toxin. µ-conotoxin CnIIIC also blocks the α3β2 nicotinic acetylcholine receptor (IC₅₀ = 450 nM) and to lesser extents the α7 and α4β2 subtypes. µ-conotoxin CnIIIC completely inhibits twitch tension in isolated mouse hemidiaphragms (IC₅₀ = 150 nM).