Absence of secretion of acetylcholine on stimulation of nerves in an unstriated muscle

Summary

1. Frog’s stomach muscle when immersed in eserinised Ringer’s solution for 2 hours shows no leakage of acetylcholine, whether extended or unextended.

2. Electrical stimulation of the muscle or its nerves does not release any acetylcholine.

3. Depolarisation with strong solutions of potassium chloride does not liberate acetylcholine.

4. Immersion in strong solutions of calcium chloride does not liberate acetylcholine.

5. Heating to 50–60° C., or treatment with ether liberates acetylcholine; the muscle also relaxes actively if heated. Adrenaline or noradrenaline is also liberated by heating.

6. As heating to 50–60° C. causes active relaxation as well as liberation of acetylcholine, it is suggested that acetylcholine is in some way connected with contractility by direct action on the contractile mechanism.

7. The above results were obtained in autumn, but in winter acetylecholine was liberated.