Selective Modulation of Chemical Transmission at a Dual-Action Synapse (with Special Reference to Baclofen)
نویسنده
چکیده
Monosynaptic, electrical-chemical EPSPs were produced in individual motoneurons of the isolated frog spinal cord by intracellular stimulation of single primary afferents. This preparation was used to assess the relationship between the modulation of chemical synaptic transmission and presynaptic invasion. It was found that at dual-action synapses Baclofen selectively depressed chemical transmission without affecting the electrically mediated response. The depression of chemical transmission results from a reduction in the number of transmitter quanta released by the presynaptic terminals following their adequate depolarization by the incoming action potential. Some other drugs depressing (Nembutal) and enhancing (Guanidine) chemical transmission and cooling also induce variability to release transmitter without affecting the presynaptic invasion.
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