236 INTERNAL SECRETION 



gastrocnemius of frogs, as well as of the forearm muscles of dogs. 

 According to Langlois, suprarenal extract produces a paralysis of 

 the motor nerve endings, similar to that provoked by curare. 

 Boruttau compared the action of adrenalin upon the striated 

 muscles to the changes which take place in the first stage of 

 fatigue. On the other hand, Dessy and Grandis believe that 

 fatigued nerve muscle preparation of the frog is stimulated to 

 renewed activity by the action of adrenalin. Panella, who con- 

 firmed this view, found that, in frogs, the action of the active 

 principle of suprarenal was antagonistic to that of curare ; it 

 neutralizes the inhibitory effect which minimal doses of curare 

 have upon the muscles, and in cases where curare paralysis has 

 already made its appearance, it hastens the return to normal 

 conditions. The results of Joteyko's investigations into the 

 nature of adrenalin, seem to show that it produces neither stimu- 

 lation nor inhibition of muscular action, but that it affects the 

 muscular sarcoplasm in such a way as to render it more sensitive 

 to nervous stimulus. These changes in irritability are, however, 

 so slight as to be demonstrable only by special methods. 



The experimental evidence which we at present possess is 

 not sufficient to decide the question, as to whether the influence 

 which adrenalin exercises upon the striated muscles is physio- 

 logical or toxic in character. Observation of the heart muscle 

 yields results which seem to point to the latter conclusion. For, 

 in addition to the changes which have been described, certain 

 phenomena are occasionally observed in connection with the 

 heart muscle, which it is impossible to regard as other than toxic. 

 In dogs, especially, both large doses of adrenalin and the injection 

 into the veins of extract of the chromaffine bodies (Biedl and 

 Wiesel), are frequently followed by arhythmia, and in some 

 instances by a sudden fluttering which terminates fatally. 



TOXIC ACTION. 



When given in moderate doses, the influence of adrenalin is 

 purely physiological, but when employed in large quantities its 

 action is violently toxic. It exercises a destructive influence upon 

 a number of tissues, and produces acute symptoms which may 

 end in death. 



The amount of the toxic dose of adrenalin is, to a certain 

 extent, dependent upon the animal species and upon the method of 

 exhibition. The intravenous injection of .1 to .2 mg. per kilo 

 usually proves fatal to dogs, rabbits, and guinea-pigs. Amberg 

 gives the toxic dose of epinephrin though this is probably not 

 identical with adrenalin as i to 2 mg. per kilo in dogs. Cats, 

 as a general rule, tolerate somewhat larger doses of adrenalin, the 

 toxic dose being as high as .5 to .8 mg. per kilo (Lesage). The 

 size of the dose, the intravenous injection of which is immediately 



