COMPARED TOXICITY OF THE POTASSIUM CHANNEL BLOCKERS, APAMIN AND DENDROTOXIN

The central toxicities of two potassium ion channel blockers, apamin a nd ol-dendrotoxin (DTx), have been compared, Both apamin and dendrotox in injected intracerebroventricularly produced signs of poisoning, inc luding tremor and ataxia; however, only DTx produced changes in brain electrical activity, with high voltage spikes and epileptiform activit y and subsequent brain damage. DTx, but not apamin, increased the ampl itude of evoked field potentials and caused repetitive firing of neuro nes in hippocampal slices. Signs of poisoning following peripheral (in traperitoneal) administration of apamin were similar to those followin g central administration, including dramatic haemorrhagic effects on t he lungs of decedent animals. These results are consistent with dendro toxin being a centrally-active neurotoxin producing epileptiform activ ity and brain damage, whilst apamin produces its most significant path ology in the lung, possibly involving a neurogenic mechanism.