Abstract

Dorsal root ganglion cells of the cat were studied in situ with intracellular microelectrodes to assess the direct effects of a convulsant barbiturate, 5-(2-cyclohexylideneëthyl)-5-ethyl barbituric acid (CHEB), on excitability of neuronal membrane. Experiments were conducted on unanesthetized, spinal cats paralyzed with gallamine. Ganglion cells were isolated from the spinal cord by severance of the dorsal roots. CHEB (1-2 mg/kg) depolarized dorsal root ganglion cells by 10 to 20 mV, reduced firing threshold and electrical resistance of the cell membrane and discharged action potentials. CHEB was without effect on firing threshold of peripheral nerve and did not elicit discharges from sensory receptors of skin or muscle. CHEB did, however, elicit discharges from the central end of the cut dorsal roots, presumably due to depolarization of intraspinal primary afferent terminals. The effects of CHEB on dorsal root ganglion cells indicate that some derivatives of barbituric acid are capable of directly exciting neural tissue.