A COMPARATIVE STUDY OF CHOLINE AND CERTAIN OF ITS ANALOGUES I. THE PHARMACOLOGICAL ACTIVITY OF ACETYLPHOSPHOCHOLINE AND ACETYLARSENOCHOLINE RELATIVE TO ACETYLCHOLINE

¹ Department of Pharmacology, University of Toronto

1. The pharmacological actions of the phosphorus and arsenic analogues of acetylcholine, acetylphosphocholine and acetylarsenocholine, are qualitatively identical with those of acetylcholine.

2. On the blood pressure of the pithed cat, on the frog's heart and on the rabbit's intestine, acetylphosphocholine shows approximately 8 per cent and acetylarsenocholine slightly more than 1 per cent of the activity of acetylcholine.

3. On the turtle's heart, the phosphorus analogue shows approximately 5.7 per cent and the arsenic analogue about 0.7 per cent of the activity of acetylcholine, while on the frog's rectus abdominis acetylphosphocholine shows approximately 15.8 per cent and acetylarsenocholine about 2.7 per cent of the activity of acetylcholine.

4. It is suggested that the manner in which acetylcholine and its analogues react with cells or the effect of the reaction products formed, is different in the case of the frog's rectus abdominis and the turtle's auricle from the mechanism of action on the frog's heart, rabbit's intestine and cat's blood pressure.