Summary
A study was made of the pattern of motor innervation and neuromuscular transmission in the longitudinal muscle of the body wall of the leech.
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1.
The chemical sensitivity of muscle fibres was tested by applying acetylcholine (ACh) iontophoretically or in the form of droplets. The depolarizing action of ACh on the muscle fibres was greatest at sites where focal synaptic potentials are recorded after stimulation of the excitatory motor neuron. In many muscle fibres several sites of high ACh sensitivity may occur, a result which suggests that the muscle fibres are multiply innervated. Histologically identified nerve terminals were consistently observed at regions of high ACh sensitivity (Figs. 6, 7).
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2.
The cholinergic blocking agent curare reversibly reduced the amplitude of the excitatory synaptic potentials evoked by the motor neuron (Figs. 4, 5).
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3.
It is suggested that ACh is the transmitter released by the longitudinal motor neuron.
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This work was supported by a United States Public Health Services predoctoral trainership to the Physiology Department, U.C.L.A. Medical School. I am grateful to Drs. Alan Grinnell and John Nicholls for good advice and support throughout the course of this work.
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Kuffler, D.P. Neuromuscular transmission in longitudinal muscle of the leech,Hirudo medicinalis . J. Comp. Physiol. 124, 333–338 (1978). https://doi.org/10.1007/BF00661382
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DOI: https://doi.org/10.1007/BF00661382