THE EFFECTS OF DRUGS ON CARDIAC OUTPUT: VI. THE EFFECT OF EPHEDRINE ON THE MINUTE CARDIAC OUTPUT OF NORMAL DOGS

INTRODUCTION  The number of drugs which have been shown to be cardiac stimulants is not large and the result of their use in combating acute circulatory insufficiency has not been encouraging. The action of three drugs commonly used for this purpose, caffeine, camphor and strychnine, has been studied by us on normal dogs,¹ and Blalock² has studied the effect of caffeine and ether on the minute cardiac output of dogs in hemorrhagic shock. Caffeine decreased the cardiac output of normal dogs and slightly increased the output in mild shock; camphor had no effect, and strychnine caused a consistent increase when given to normal dogs. Ether, in mild shock, caused an increase in the output but in severe shock was found to decrease the output. The action of epinephrine hydrochloride is well known by virtue of the work of many investigators; Pilcher, Wilson and Harrison³ have recently shown that following the