SYNERGISMS AND ANTAGONISMS OF ACETYLCHOLINE BY QUATERNARY AMMONIUM SALTS

¹ The Department of Pharmacology, University of Edinburgh

1. Compounds of the series Me₃NMe. to Me_3NAm. produce a full additive action when combined with acetylcholine on the frog's auricle and other tissues tested.

2. The series Me₃NHex. to Me₃NCetyl produces an antagonistic action, and the intensity of antagonism increases with increasing length of chain.

3. The compounds Et₄N, Pr₄N, and Br₄N are similar as regards their power of antagonising acetylcholine.

4. The compounds Et₄As, Me₂NPiperidine, and Et₂NPiperidine have similar antagonistic actions, which are about one-tenth that of Et₄N.

5. Methylene-blue and procaine antagonise the action of acetylcholine on the frog's heart, rectus abdominis, and rat's gut, but potentiate its action on the leech muscle.

6. Various antagonists to acetylcholine, such as atropine and curarine, show marked tissue specificity.

7. The significance of these results in relation to certain general theories of drug action has been discussed.It is with pleasure that I put on record my indebtedness to Professor A. J. Clark for his kind hospitality, and for his constant help and Synergisms and Antagonisms of Acetylcholine advice. The expenses of this research were in part defrayed by the Moray Fund, for which help I express my thanks.