抄録
1. In unanaesthetized acute spinal cats, intravenous injection of GABA above 0.30mg/kg consistently depressed the extensor monosynaptic reflex, while the flexor monosynaptic reflex was usually facilitated. GABA action gradually decreased when systemic administration was repeated with short intervals.
2. These actions of GABA was not demonstrated in decerebrate cats.
3. The effect of GABA on the flexor monosynaptic reflex was remarkably altered by changes in the internuncial activity produced by cutaneous, Group II and III afferent conditioning volleys.
4. GABA action was not influenced by Group I afferent and antidromic axoncollateral conditioning volleys.
5. Nembutal anaesthesia resulted in elimination of GABA action. Strychnine abolished or reduced the facilitatory effect of GABA on the flexor monosynaptic reflex.
6. It was concluded that GABA may selectively block some excitatory interneurones which are intercalated in the reflex pathways of Group II and III fibers of muscle nerve and of some cutaneous afferent fibres and are tonically controlled by suprasegmental activity.
