Reversal of paralysis in nerve-muscle preparations isolated from animals with hereditary motor endplate disease.

Motor endplate disease (med) in the mouse is an hereditary disorder of the skeletal neuromuscular system. Affected animals suffer a 'functional denervation' of skeletal muscle (Duchen & Stefani, 1971). Muscle fibres do not respond to indirect excitation, but motor nerve terminals release transmitter spontaneously. Spontaneous transmitter release can be enhanced by raising [K+]o or by exposing muscles to red-back spider venom and functional transmission following indirect stimulation may be restored by 4-aminopyridine.