Abstract

The pharmacological properties of certain derivatives of choline have been investigated with the following results.

1. In the choline group: The propionyl and butyryl ester have weaker muscarine-like properties than acetyl choline. Their nicotine action on the blood pressure is more potent than that of acetyl choline. In contracting the denervated muscle propinoyl choline is nearly as active as acetyl choline, butyryl choline is about half as active.

The butyl and vinyl ethers of choline both have a very strong nicotine action upon the cat's blood pressure. The butyl ether has practically no muscarine action while the vinyl ether is in this respect very close to the ethyl ether of choline. The investigated ethers (methyl, ethyl, vinyl, butyl) have a marked action on the denervated cat's muscle but are notably weaker than the esters.

The esters are all about equally active in liberating adrenalin from the suprarenals after atropine; they are far more powerful in this respect than the ethers even though they cause a much smaller hypertension.

2. In the methyl choline group: Compared with choline, α-methyl choline has weaker muscarinic properties but an equal nicotine action.

Acetyl-α-methyl choline is notably less active than acetyl choline as far as the muscarine action is concerned. Its nicotinic potency is of the same order as that of acetyl choline.

Compared with choline, fl-methyl choline has a weaker muscarine and nicotine action, but on the denervated muscle they seem equally active.

With regard to the muscarine action acetyl- and propionyl-fimethyl choline are weaker than their homologues in the choline series, if small doses are used; they become more active than their choline homologues in large dosage. These compounds do not elicit nicotinic hypertension and on the denervated muscle they are about a thousand times less active than acetyl and propionyl choline.

The ethyl ether of fl-methyl choline has a weaker muscarine action than the ethyl ether of choline. It does not produce nicotinic hypertension and has a very low activity upon the denervated muscle. Injected into the normal cat the ethyl ether produces an intense miosis which is not shown by injection of the esters of fl-methyl choline or of a lethal dose of the ethyl ether of choline.

3. Of all the compounds investigated, the acetyl ester of 13-methyl choline appears actually to offer the greatest possibility of clinical usefulness, since it is approximately as potent as acetyl choline in lowering blood pressure when given intravenously; it has no demonstrable nicotinic action on the circulation, and it is so much more stable than acetyl choline that it is effectively absorbed from the intestinal tract and is much more potent than acetyl choline when injected subcutaneously.