Funnel web spider venom produces spontaneous action potentials in nerve
Venom from the lethal Australian spider, Atrax robustus, causes fasciculation of muscles in vivo and in isolated diaphragms in mice. Spontaneous end-plate potentials were recorded in muscle fibres exposed to the venom and associated spontaneous electrical activity could also be recorded from the phrenic nerve. It was proposed that the venom produces muscle fasciculation by causing abnormal, spontaneous, repetitive firing of motor nerves. The mechanism of this action was investigated in aplysia neurones. The venom produced abnormal, spontaneous, repetitive inward currents in voltage clamped neurones and changed the current-voltage characteristics of the surface membrane. It is suggested that the basic mode of action of Funnel-web venom is to change the electrical field in nerve membrane.