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

The intense pharmacological activity of acetyicholine and its physiological significance as the chemical mediator of impulses at the endings of cholinergic nerve fibers, lead to interest in the mechanism by which this substance produces its action on cells. The valuable investigations of A. J. Clark (1) on frog’s heart and rectus abdominis, indicate that a reversible monomolecular reac-tion occurs between acetylcholine and some substance either in the cell or on its surface. As a result of recent investigations on the embryonic hearts of Fundulus, Armstrong (2) concluded that acetylcholine does not have a dirept action on the cardiac musculature but produces its action by stimulating the intramyocardial vagus postganglionic fibers which in turn inhibit the heart. Such a view is incompati-ble with the conception entertained at present by most pharma-cologists. Whatever the site of action of acetylcholine, it is of interest to investigate the manner in which it reacts with cell receptors and the relation between the amount of drug fixed by these receptors and the action produced. A study of the action of certain analogues of choline and acetyicholine chlorides seemed to us a possible means of obtaining further information as regards the manner in which acetylcholine influences cells. The results of quantitative pharmacologica