The possibility of desensitization of the motor end‐plate to ACh during tetanus — as proposed by T hesleff — and the possible role of this desensitization for production of Wedensky inhibition of the neuromuscular transmission, have been tested and are discussed. As in T hesleff 's experiments increased concentration of NaCl has been used to obtain block of contraction and pure end‐plate potentials. Mechanical registration of the contractions and extracellular recording of end‐plate potentials were employed. No signs of Wedensky‐inhibition could be obtained by increasing the NaCl‐concentration in the bath. Previous results indicate that the state of the motor end‐plate after long sustained strong increase in the NaCl‐concentrations must be rather unphysiological. The present results and also previous ones quoted in the discussion do not indicate any certain desensitization of the motor end‐plate to ACh under physiological conditions. A mechanism of this type can probably not be of particular significance for the production of the very rapidly occurring Wedensky inhibition seen, for example, during curarization.
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Lilleheil et al. (1961) studied this question.