CHOHLINERGIC TRANSMISSION IN THE RECURRENT FACILITATORY PATHWAY OF THE SPINAL MOTONEURON OF THE TOAD
1971 年 21 巻 5 号 p. 475-487
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1971 年 21 巻 5 号 p. 475-487
1. The VR-EPSP of the spinal motoneuron of the toad was investigated by intracellular recording. Concerning the size, time course, and effect of membrane potential displacements, no essential difference was found between the VR-EPSP in the toad and that in the frog. A remarkable facilitatory effect of the DR-EPSP on the VR-EPSP was observed.
2. The effects of various pharmacological agents on the VR-EPSP were tested by topical application using a double- or triple-barrel microelectrode, or by application to the perfusion fluid through the vascular system.
3. The VR-EPSP was increased in size and the decaying phase was prolonged by topical application of physostigmine. Acetylcholine was effective in increasing the size of the VR-EPSP when applied topically or through the vascular system.
4. A transient depolarization, which may be called acetylcholine potential, was recorded intracellulary when acetylcholine was applied extracellularly by a brief outward current from the microelectrode filled with acetylcholine.
5. Curare was found to have no effect on the VR-EPSP, while nicotine and atropine were effective in depressing the VR-EPSP.
6. Cholinergic trasmission at the synapse between motor axon collaterals and motoneurons in the toad was demonstrated. It was, furthermore, pointed out that the present investigation did not exclude the possibility of electrical interaction between motoneurons.
