Neuromuscular Transmission in Murine Muscular Dystrophy (129 ReJ Strain)

Abstract

Neuromuscular transmission in diaphragm and extensor digitorum longus (EDL) muscles from normal and dystrophic (129/Rej dy/dy) mice was compared using electrophysiological and pharmacological techniques. Indirectly evoked twitch responses of dystrophic EDL muscles were more resistant to curare than those of normal muscles whereas there was no difference in curare sensitivity between diaphragm muscles from normal and dystrophic mice. Spontaneous and evoked transmitter release was investigated using conventional intracellular recording techniques. Endplate potential (e.p.p.) amplitude and quantum content (m) were greater than normal in the dystrophic EDL. In the dystrophic diaphragm e.p.p. amplitude was larger, but m did not differ from normal. In the cut-fibre EDL transmitter release followed a binomial distribution. The probability of quantal release (p) and the number of quanta available for release (n) were calculated using the binomial model. Probability of release was greater in the dystrophic EDL but n was similar in normal and dystrophic muscles...