COMPARISON OF POTENCIES OF A SERIES OF BARBITURATES AT NEUROMUSCULAR-JUNCTION AND ON CENTRAL NERVOUS-SYSTEM

Abstract

The ability of a series of barbiturates to depress the depolarizing action of carbachol at the end-plate of guinea-pig lumbrical muscle was studied. The compounds studied were: amobarbital, aprobarbital, barbital, barbituric acid, butabarbital, butalbital, dimethylbutylethyl barbituric acid, hexobarbital, mephobarbital, metharbital, secobarbital, thiamylal and thiopental. The depressant activity was sensitive to small changes in structure of the compounds, strongly suggesting that a specific receptor site was involved in the interaction of the drug with the tissue. The observed relative potencies on the motor end-plate were compared with their anesthetic potencies assayed on tadpoles. The 2 potencies were in agreement for all the compounds studied, including the convulsant member of the series.