Acetylcholine-releasing effects of some nicotinic agents on chick biventer cervicis nerve muscle preparation.

Abstract

SummaryThe mechanism of action of some nicotinic agents has been studied on the baby chick biventer cervicis nerve muscle preparation. The effects of various nicotinic agents on this preparation were blocked by 1.2 × 10—2M triethylcholine (TEC) or by neuromuscular blockade achieved by TEC treatment with interrupted tetanic nerve stimulation, whereas the dose-responsive curve of acetylcholine (ACh) was not altered. These results suggest that the nicotinic agents tested are presumably acting primarily at the nerve terminals rather than at the receptor sites on the postjunctional membrane. After the effects of the nicotinic agents were completely blocked by TEC alone, the muscle was still responsive to nerve stimulation. This suggests that the TEC blockade of the nicotinic effects of the drugs tested may be at the membrane site of the nerve terminal since ACh is still available in the storage site for release after TEC blockade. In the same preparation, the responses to most of the nicotinic agents were mark...