THE SUPRARENAL SYSTEM 2OI 



of the heightened blood-pressure, but of the direct action upon the 

 heart of the substance itself. Thus, the intravenous injection of 

 suprarenal extract will bring back life into an animal poisoned 

 with chloral, in which the action of the heart is almost or entirely 

 obliterated. The injection is followed by a progressive increase 

 in the rapidity and power of the contractions ; the blood-pressure, 

 which had fallen almost to nothing, rises ; and, after a second 

 injection, the heart resumes its normal activity which is main- 

 tained. A similar result may be obtained after poisoning with 

 potassium salts, which bring about a cessation of diastole and 

 thus are typical cardiac poisons (Gottlieb). 



The resuscitating effect of adrenalin upon the heart the man- 

 ner in which it hastens and strengthens cardiac contraction is 

 undoubtedly an important factor in the analeptic action, already 

 described, which this substance has in conditions of collapse due 

 to paralysis of the vessels or to temporary cardiac insufficiency. 



The action of adrenalin mav also be observed in hearts 



j 



which have been removed from the living body. Oliver and 

 Schafer experimented with isolated frogs' hearts through which 

 normal saline solution was allowed to circulate. They found that 

 suprarenal extract produces spontaneous contraction in a motion- 

 less heart ; in the case of a feebly beating heart, the beats become 

 stronger and more rapid, the irregularity disappears, and rhythm 

 is restored. 



The tonic influence of adrenalin upon the isolated mammalian 

 heart when flooded by Langendorff's method is very clearly 

 shown by the acceleration and remarkable increase in power of 

 the contractions (Gottlieb, Hedbom, Braun and Mager, Cleg- 

 horn). Weakness of the heart's action, arising from prolonged 

 deprivation of the nutrient fluid or from the action of toxins, is 

 invariably corrected by the application of adrenalin, and it is not 

 until after the method has been continued for some time that the 

 reduced cardiac activity again becomes apparent in the guise of 

 arhythmia and reduction in frequency. Hering-Bock found that 

 an increase in the pulse-rate and a stronger cardiac contraction 

 also followed the employment of adrenalin in the isolated cardio- 

 pulmonary circulation. 



Gottlieb endeavoured to discover with isolated frogs' hearts, 

 whether suprarenal extract acts directly upon fhe cardiac muscles 

 or upon the ganglia. The action of the ventricle was arrested by 

 means of the first ligature of Stannius between the sinus venosus 

 and the auricle ; by the injection of a small quantity of suprarenal 

 extract, it was next induced to contract rhythmically in the same 

 manner as after the so-called second ligature of Stannius. After 

 the application of the second ligature of Stannius, however, the 

 ventricle, which was then entirely deprived of its ganglia, failed 

 to contract even in response to injections of suprarenal extract, 

 and it responded to mechanical stimulus with a single contraction 



