CORRELATES OF ANESTHETIC PROPERTIES IN ISOLATED SPINAL-CORD - CYCLOBUTANES

Two halogenated cyclobutanes, one anesthetic and one not, were compare d on receptor-specific pathways in isolated neonatal rat spinal cord. The anesthetic 1-chloro-1,2,2-trifluorocyclobutane depressed the monos ynaptic reflex (glutamate non-NMDA receptors) and abolished a slow ven tral root potential (glutamate NMDA, non-NMDA and tachykinin receptors ). This compound slightly enhanced the muscimol-evoked dorsal root pot ential (GABA(A)) but reversibly depressed the dorsal root potential el icited by dorsal root stimulation. The non-anesthetic 1,2-dichlorohexa fluorocyclobutane increased monosynaptic reflex, depressed slow ventra l root potential similar to 50%, had little effect on muscimol-evoked dorsal root potential, and irreversibly depressed dorsal root-evoked d orsal root potential. Hypoxia accounts for slow ventral root potential depression, but not monosynaptic reflex enhancement. In this preparat ion and for this pair of compounds, anesthetic properties are related to blockade of transmission at glutamate synapses, with a small compon ent of GABA(A) enhancement. Monosynaptic reflex increase may be relate d to the non-anesthetic cyclobutane's convulsant and anti-anesthetic p roperties.