Experiments with Quinidine. 



175 



mass involved is too small, a path long enough to permit the 

 development of a circus becomes impossible; (2) if the rate of 

 conduction is too fast, the stimulus returns to its starting point 

 before the muscle at that point is ready for its reception; (3) if 

 the refractory period of the muscle at the starting point is pro- 

 longed beyond the time consumed by the stimulus to make its 

 circuit, the muscle cannot be reexcited. The establishment and 

 maintenance of circus movement depends then on (1) a large 

 mass of muscle; (2) a slow rate of conduction, and (3) a brief 

 duration of the refractory period. 



When it became clear to us after trial in patients that with 

 quinidine one could terminate the state of fibrillation in about 

 half the individuals afflicted, we began early in 192 1 to examine 

 the nature of the activity of this drug. Certain effects which we 

 found the drug to possess on the heart and circulation we reported 

 to this Society at its meeting on May 18, 192 1. At that time we 

 reported that the study of its effect on the rate of conduction of 

 impulses through the muscle was under way. We have since 

 added to these studies an investigation of its effect on the duration 

 of the refractory period. On these two phases of the subject we 

 report now. 



During the course of our work, Lewis's report dealing with 

 the same phases of the subject has been published. Although 

 the general viewpoints of the two researches are the same, they 

 show a certain difference in that we have attempted to maintain 

 the conditions of the experiments as nearly natural as possible 

 and have, perhaps, in consequence of this difference in plan, 

 arrived at somewhat different results. 



These experiments were carried out on dogs, anesthetized with 

 ether only. Artificial respiration, at constant pressure and volume, 

 was maintained by the method of Meltzer and Auer. The chest 

 was split and the right auricle exposed by an incision of the 

 pericardium. A wick was sewed to the heart near the base and 

 another near the apex of the auricular appendix. The two wicks 

 led to non-polarizable electrodes. These electrodes formed parts 

 of two separate galvanometer circuits which were completed by 

 indifferent electrodes inserted in the muscle of the chest wall. 

 Electrodes were also placed on the right fore and left hind limbs. 



