THE ACTION OF CHLORPHENESIN CARBAMATE ON THE FROG SPINAL CORD

Studies were carried out to elucidate the mechanism of action of chlorphenesin carbamate (CPC) and to compare the effect of the drug with that of mephenesin on the isolated bullfrog spinal cord. Ventral and dorsal root potentials were recorded by means of the sucrose-gap method. CPC caused marked hy...

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Bibliographic Details
Published in:Japanese journal of pharmacology 1980/02/01, Vol.30(1), pp.29-36
Main Authors: AIHARA, Hironaka, KURACHI, Michio, NAKANE, Sadao, SASAJIMA, Michitada, OHZEKI, Masahiro
Format: Article
Language:English
Subjects:
Action Potentials - drug effects
Animals
Anura
Calcium - physiology
Chlorphenesin - analogs & derivatives
Chlorphenesin - antagonists & inhibitors
Chlorphenesin - pharmacology
Electric Stimulation
Evoked Potentials - drug effects
Excitatory Amino Acid Antagonists
Ganglia, Spinal - drug effects
In Vitro Techniques
Magnesium - physiology
Mephenesin - pharmacology
Picrotoxin - pharmacology
Rana catesbeiana
Spinal Cord - drug effects
Strychnine - pharmacology
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Summary:Studies were carried out to elucidate the mechanism of action of chlorphenesin carbamate (CPC) and to compare the effect of the drug with that of mephenesin on the isolated bullfrog spinal cord. Ventral and dorsal root potentials were recorded by means of the sucrose-gap method. CPC caused marked hyperpolarizations and depressed spontaneous activities in both of the primary afferent terminals (PAT) and motoneurons (MN). These hyperpolarizations were observed even in high-Mg2+ and Ca2+-free Ringer’s solution, suggesting that CPC has direct actions on PAT and MN. Various reflex potentials (dorsal and ventral root potentials elicited by stimulating dorsal and ventral root, respectively) tended to be depressed by CPC as well as by mephenesin. Excitatory amino acids (L-aspartic acid and L-glutamic acid) caused marked depolarizations in PAT and MN, and increased the firing rate in MN. CPC did not modify the depolarization but abolished the motoneuron firing induced by these amino acids. However, mephenesin reduced both the depolarization and the motoneuron firing. The dorsal and ventral root potentials evoked by tetanic stimulation (40 Hz) of the dorsal root were depressed by the drugs. These results indicate that CPC has an apparent depressing action on the spinal neuron, and this action may be ascribed to the slight hyperpolarization and/or the prolongation of refractory period.
ISSN:0021-5198
1347-3506
DOI:10.1254/jjp.30.29