Effects of Ethenzamide on Spinal Reflex Potentials in Cats

Abstract

The pharmacological effect of ethenzamide on spinal reflex potentials was studied in the spinal cats, and this effect was compared with that of methocarbamol which wasa centrally acting skeltal muscle relaxant. The effects of intraduodenal medication when ethenzamide was mixed with methocarbamol and then combined addivively with caffeine were also compared with the effect of ethenzamide on the spinal reflex potentials.
The spinal reflex potentials were dosis-dependently depressed by ethenzamide just as by methocarbamol, which was similar to mephenesin. The inhibitory potencies of ethenzamide were to be inferior to those of methocarbamol, and the duration of it's action of ethenzamide was also slightly shorter than methocarbamol. Therefore, ethenzamide markedly depressed the polysynaptic reflex potential and then slightly decreased the monosynaptic reflex potential. The inhibition of spinal reflex potentials induced by ethenzamide could antagonize an excitory potentials of picrotoxin and metrazol but could not antagonize that of strychnine. In opposed to that, methocarbamol could antagonize the central stimulants except picrotoxin, the same as mephenesin. In these points, the action mode of ethenzamide might be differed from that of methocarbamol. On the other hand, these inhibitory effects synergetically potenciated the monosynaptic reflex potential more than polysynaptic reflex potentials by an administration of both drugs. These inhibitory potencies were much increased by additive caffeine especially on the polysynaptic reflex potentials. This potentiation may be based on sensitization of interneuronal pathway induced by prostaglandin, which is markedly synthetized by caffeine.