Toxin I from the snake Dendroaspis polylepis polylepis: a highly specific blocker of one type of potassium channel in myelinated nerve fiber.
Toxin I from the venom of the black mamba snake Dendroaspis polylepis polylepis specifically blocks one component of the K-current (IKf1) in the frog node of Ranvier, with a high affinity (Kd = 4 X 10(-10) M) without significantly affecting either the others components of the K current (IKf2 and IKs) or the Na-current. Moreover, for toxin concentrations corresponding to 10- or 100-fold the Kd value, the block was almost irreversible.
D000818:Animals; D003864:Depression, Chemical; D004546:Elapid Venoms / Q000494:pharmacology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism*; D011893:Rana esculenta; D011901:Ranvier's Nodes / Q000187:drug effects*; D012964:Sodium / Q000378:metabolism
D004546:Elapid Venoms; D007473:Ion Channels; D012964:Sodium; D011188:Potassium