抄録
1. Neuro-muscular transmission of excitation, excitatory junction potentialactivation- contraction link and tension development in the red muscle of the silver carp (Carassius auratus) were investigated and the results were compared with those of the white muscle and with the frog slow fibres.
2. Miniature excitatory junction potentials (mejps) could be recorded from the postsynaptic membrane. The mean amplitude was 0.45mV and the mean interval was 421msec. The histograms of the mejp amplitudes and of intervals were skew. The mejps and excitatory junction potentials (ejps) produced by nerve stimulation were probably due to release of acetylcholine from the nerve terminals.
3. The observation that ejps were recorded in many parts of the same muscle fibre in response to nerve stimulation suggested a diffuse innervation of the muscle fibre.
4. The equilibrium potentials of the ejps recorded in red muscle ranged between -30 and -35mV.
5. Excess calcium increased the effective resistance of the postsynaptic membrane and increased the amplitude of the mejps and ejps. Excess magnesium did not change the membrane resistance but reduced the frequency of the mejps and the amplitude of the ejps.
6. The delay in generation of ejp after the peak of the nerve action potential was 0.53msec.
7. The relation between the membrane potential and tension development was determined. The critical level of membrane depolarization required to induce tension development was 60mV and this level was exceeded by the amplitude of the ejp.
