QUININE: EFFECTS ON NORMAL AND DENERVATED SKELETAL MUSCLE AND ON THE ACETYLCHOLINE AND PHYSOSTIGMINE ACTIONS ON SKELETAL MUSCLE

¹ From the Department of Physiology, University of Chicago, and the Department of Physiology and Pharmacology, Loyola University, School of Medicine, Chicago

Quinine produces the following effects on the in vivo nerve-muscle preparation of the dog:

1. Potentiation of muscle twitches.

2. Depression of muscle tetanus, especially in larger doses.

3. Prolongation of the least effective interval for the summation of two successive stimuli.

4. Block of the normal physostigmine potentiation.

5. Block of the post-physostigmine acetylcholine muscle effects.

6. Additional depression of muscle twitches in a partially curarized animal.

7. Block of the acetylcholine decurarization.

8. Potentiation of the denervated muscle twitch.

9. Block of the acetylcholine effects on the denervated muscle.

The relation and significance of these findings to the clinical use of quinine and physostigmine in myotonia and myasthenia are discussed.