A letter from another scientist:
Decades ago I recall that a scientist who was studying the junction between nerve and muscle was getting funding from some arm of the Military Security Complex. Why? Well toxins act on this junction disrupting the chemical connection that links motor neuron to muscle cell. One example of such an agent is curare which breaks the connection by competing with the neuromuscular transmitter, acetylcholine, for the acetylcholine receptor and hence blocking muscle contraction. Death comes quickly from paralysis of the diaphragmatic muscle which leads to suffocation.
Organophosphates like Sarin also act at the neuromuscular junction and other sites in a more complicated way than curare.