The effect of the venom of the black widow spider Latrodectus mactans tredecimguttatus on the giant neurones of Periplaneta americana

Abstract

The effects of the venom of the black widow Latrodectus mactans tredecimguttatus have been studied by intracellular recordings from giant neurones at the sixth abdominal ganglion of Periplaneta americana. The venom induces: (i) a progressive decline of the resting potential of the giant neurones; (ii) failure of synaptic transmission through a progressive reduction of the EPSP; (iii) spontaneous repetitive firing of the giant neurones; (iv) alterations of the shape and reduction in size of the propagated action potential. It is suggested that the venom causes a massive release of transmitter which in turn depolarizes the post-synaptic membrane.