Abstract
1. The degree of in vitro inhibition of rat brain cholinesterase caused by five organic phosphorus compounds is compared with their intraperitoneal toxicity to mice. These compounds are: (1) tetraethyl pyrophosphate, (2) [(C2H5O)2 OPO]2 POCH3, (3) diisopropyl fluorophosphate, (4) diisopropyl chlorophosphate, (5) p-chlorophenyl diethoxy phosphine oxide. The concentrations in which these compounds cause 50 per cent inhibition of cholinesterase activity and their LD50'S in micromols and mgm. per kgm. are presented in tabular form.
2. The logs of the LD50'S of these five potent cholinesterase inhibitors are proportional to the logs of the molar concentrations causing 50 per cent inhibition of cholinesterase. The significance of this finding is discussed.
The authors wish to express their appreciation to Mr. Jack P. Saunders and Doctor Williamina A. Himwich for technical advice, to Miss Frieda F. Faiman and Mrs. Lottie K. Jandorf who did the statistical analyses, and to the Technical Command, Army Chemical Center, and the Monsanto Chemical Company, who supplied the compounds investigated in this study.
Footnotes
- Received March 29, 1948.
- 1948 by The American Society for Pharmacology and Experimental Therapeutics
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