THE ACTION OF CERTAIN CHOLINE DERIVATIVES ON THE CORONARY FLOW

The literature dealing with the effect of choline bodies on the coronary vessels is not extensive and contains apparently conflict-ing reports. Smith, Mifier, and Graber (10) found that acetyl-choline caused an increase in the rate of flow through the perfused rabbit heart. Wedd and Fenn (12) later observed only decreased coronary outflow for that animal following acetylchollne. Orze-chowski (7) studied the cat heart by the Langendorff method and reported that acetylcholine in concentrations of 10 to 10_s caused a diminution in coronary outflow. More recently Golden-berg and Rothberger (3) have investigated the action of acetyl-choline on the mammalian heart; the outflow of the perfused cat heart was reduced, while that of the dog in the heart-lung prepa-ration was augmented. Comroe and Starr (1) studied acetyl-beta-methylcholine and stated that this substance in the smallest effective doses caused a slight decrease in coronary flow in the perfused heart of the cat or rabbit; with larger doses the flow changes were variable, at times increasing and at others decreas-ing, and often first decreasing and then increasing, corresponding to changes in rate and amplitude. The present paper is a report of further studies on the action of acetylcholine and of acetyl-beta-methyicholine and carbarninoyl choline on the coronary flow in the heart of the dog, rabbit, and cat. ’ The hearts of 36 rabbits and of 28 cats were perfused. A 1 The following chemical preparations were used in this study: acetyicholine hydrochloride, Merck, and acetylcholine chloride by Hoffman LaRoche; acetyl-beta-methyicholine (“Mecholyl”) was supplied by Merck and Company of Rah-way, who also contributed some of the carbaminoyl choline. In most experiments with the last named drug the preparation used was “Doryl ” which was generousl