Small Doses of Anesthetics

Abstract

It was previously noted that, while ordinary concentrations of sodium amytal diminished or abolished tone and activity of isolated intestine and uterus, minute doses seemed to be pressor. 1 Is the same “reversal” effect to be found in whole intact animals? Picrotoxin causes convulsions in mice. The convulsions may be stopped or prevented by a proper dose of anesthetic. Indeed a method for biological assay of the hypnotics has been based on this antagonism, 2 and picrotoxin has been suggested as an antidote for barbiturate poisoning. 3 Thus it seems that wherever the points of action of these 2 types of poisons may be, they are sufficiently the same to exhibit a mutually antagonistic effect. Knowing that a convulsant dose of picrotoxin would be “neutralized” by a sufficient amount of anesthetic, would a sub-convulsant dose of picrotoxin become convulsant in the presence of a small, or excitatory, or stimulant dose of anesthetic?

The minimal convulsant dose of picrotoxin was determined in about 60 mice to be between 2.75 and 3.0 mg. per kg.; 2.75 mg. per kg. did not cause convulsions. Solutions of sodium pentobarbital (sodium ethyl-methyl-butyl barbiturate) and sodium amytal (sodium iso-amyl-ethyl barbiturate) were used interchangeably in equivalent doses to represent the anesthetics, since ether, alcohol or chloroform would have introduced the complicating factor of peritoneal irritation.