THE ANTAGONISM BETWEEN EPHEDRINE AND PROCAINE AFTER CISTERNAL INJECTION DURING MORPHINE-SODIUM AMYTAL ANESTHESIA AND ETHER ANESTHESIA

¹ Department of Pharmacology, University of Kansas, School of Medicine, Kansas City

The efficacy of ephedrine sulphate as an antagonist to procaine hydrochloride was tested by limiting the actions of the drugs, partially and temporarily, to the medulla. Localization was accomplished by cisternal injection. We believe the site of injection used rules out some of the complicating factors which are produced by rapid excretion, detoxication and differential fixation following other methods of administration.

It was observed that resistance of the circulatory centers to procaine depression was generally greater than resistance of the central respiratory mechanism. Anoxemia is apparently the most damaging factor in circulatory depression accompanying procaine respiratory paralysis, and adequate artificial respiration is usually definite protection against this anoxemia. This contention is supported in the experimental results obtained by Isenberger (12), in which he demonstrated the value of artificial respiration and administration of oxygen in respiratory and circulatory depression following intraspinal and intravenous procaine poisoning.

It is evident that ephedrine is antagonistic to procaine by actions other than its peripheral circulatory effects. Certainly it is true that improved circulation from intracisternal ephedrine cannot always be entirely responsible for the early return of spontaneous breathing, in animals with respiratory paralysis induced by intracisternal procaine. Ephedrine stimulated nervous structures subserving depressed reflexes almost instantaneously in these experiments. Important experimental evidence on this subject has been presented by Schmidt (13), and Wright (14).

No consideration of the patency of the foraminae connecting the cistern and fourth ventricle has been raised in this discussion. Whether the procaine found its way into the central nervous tissue through open foraminae or was transported by obscure physicochemical processes, the effects, rapid respiratory paralysis and abolition of higher reflexes, were consistently obtained.