Continuous measurement of the effect of a depressing drug upon the organism.

Abstract

The apparatus described was used in measuring the effect of nembutal upon dogs. It comprises an electrical circuit arranged to deliver, either to the animal or to a voltmeter, a d.c. make-break shock of 0.2 sec. duration and variable voltage. A resistance which is low in comparison with that of the animal is placed in parallel with the animal in order to minimize the effect of changes in the animal''s resistance (which varied from 5,000-25,000 ohms). The voltage required to induce a flexion response 4 inches in magnitude is periodically detd. It is observed that 10-20 mins. after an intraperitoneal inj. of 0.08 grains of nembutal/lb. of body-wt., the voltage required to elicit this response is about 250% of that required for undrugged animals, and individual differences in sensitivity to electrical shock are much reduced. The effect of the drug wears off until an hr. later the voltage required to effect the response is only 150% of normal.