THE INTERACTION BETWEEN PROCAINE, COCAINE, ADRENALINE AND PROSTIGMINE ON SKELETAL MUSCLE

¹ From the Department of Pharmacology, Oxford

1. The interaction of procaine or cocaine with prostigmine and adrenaline has been studied on the cat's gastrocnemius stimulated indirectly by single maximal shocks. Procaine and cocaine have an action like that of curarine, but whereas curarine depresses normal contractions more than it depresses those seen after the injection of prostigmine, procaine or cocaine depress those seen after prostigmine very greatly while exerting little action on normal contractions.

2. After the injection of procaine or cocaine, the augmentor action of prostigmine is abolished, while after the injection of curarine, the augmentor action of prostigmine persists.

3. Adrenaline, injected after prostigmine, has been shown to augment muscle contractions. Although procaine abolishes the action of prostigmine, it does not abolish the augmentor action of adrenaline injected after prostigmine.

4. If adrenaline is injected after prostigmine, the injection of procaine then depresses the effect of prostigmine little or not at all.

5. While the above effects of procaine may be regarded as like those of curarine, procaine also appears to depress the production of acetylcholine at the neuromuscular junction.