Abstract
1. Morphine inhibits reversibly the contractions of eserinized leech muscle due to acetyl-choline.
2. An approximately constant ratio exists between the amounts of morphine present in the medium and the minimum quantities of acetyl-choline necessary to give a contraction in presence of them.
3. The following morphine derivatives—heroin, codeine, dionine—behave similarly to morphine, heroin being a more powerful inhibitor than morphine and codeine and dionine less powerful inhibitors. Apomorphine is inactive as an inhibitor of acetyl-choline contraction.
4. Morphine also inhibits reversibly the contractions of noneserinized leech muscle due to choline and nicotine.
5. Narcotine, papaverine and cotarnine have no definite inhibitive actions on acetyl-choline contractions of leech muscle in the concentrations tested.
Footnotes
- Received February 14, 1937.
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