Abstract
THE properties of individual synapses of the motor axon which innervates the opener (dactylopodite abductor) muscle in the crayfish walking leg have been investigated by Dudel and Kuffler1, who placed an external microelectrode close to the synaptic region to record the flow of current through the post-synaptic muscle fibre membrane during the action of the neuromuscular transmitter2. With low frequencies of stimulation of the motor axon individual synapses showed frequent failures of transmission, and the synaptic currents generated by successful transmission were small, often equal in size to a single externally recorded spontaneous miniature potential. The latter event was found to equal one quantal unit of transmitter action. At higher frequencies of stimulation, the probability of failure of transmission decreased, and the synaptic currents attained a larger average size, indicating that the output of transmitter substance from the presynaptic terminals had increased. The postsynaptic potentials recorded internally from the muscle fibres were correspondingly larger at the higher frequencies of stimulation. These observations indicate that facilitation at the crayfish neuromuscular junction is the result of some process which gives rise to a higher probability of release of transmitter substance at the higher frequencies of stimulation or during the course of a train of closely spaced stimuli.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.