Abstract
1. In these experiments the attempt was made to obtain quantitative measures of the catalepsy produced in animals by the injection of bulbocapnine.
2. It was found that under the influence of bulbocapnine a monkey will grasp a horizontal bar and hold on so firmly that it is able to support its entire body weight even when holding with one hand only. This hanging response is completely absent in normal adults not under the influence of bulbocapnine.
3. This hanging response apparently can be used as a measure of the catalepsy, since it appears and disappears simultaneously with the cataleptic condition.
4. There is a period of five to ten minutes after the injection of the drug before the hanging response appears. It increases in strength very rapidly and reaches a maximum within fifteen to thirty minutes, with a gradual decrease during the next few hours, until it disappears.
5. Doses up to 7 to 8 mgm. per kilogram body weight do not elicit the hanging response.
6. The response appears with doses of 9 mgm. or more. With larger doses up to 17 mgm., the maximum strength of the hanging response and its total duration show a proportional increase. With doses above 17 mgm. the total duration of the effect continues to increase, but the maximum hanging time remains the same. In other words, the maximum hanging time is attained with doses of 17 mgm., and an increase in the dose will not make the animal hang longer in any one test. In adult monkeys this maximum hanging time is approximately sixty seconds, and the maximum total duration of the effect may be as long as seven hours or more.
7. Doses of 40 mgm. and above produce hyperkinetic phenomena lasting as long as forty minutes after the injection, during which time the animal refuses to hang. Afterward the response appears and persists usually for several hours.
8. The maximum hanging time is much greater in young than in adult animals. One young animal hung for one hundred and fifty seconds, in contrast to the maximum of sixty-one seconds for adults. The new-born animal in which this grasp reflex was still present hung as long as forty minutes.
9. The strength of the hanging response is equal in the right and left hands. The curves for the two hands parallel one another very closely.
10. There are great variations in the susceptibility of the different animals to the drug, but the same doses in the same animal always had a very similar effect.
11. The relationship of the hanging response to catalepsy, flexor tone, and the grasp reflex, seen in new-born infants, was discussed.
Footnotes
- Received August 15, 1931.
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