THE SUPRARENAL SYSTEM 259 



of Weiss and Harris and others, seem to show that the action of 

 adrenalin is similar in type to that of muscarin ; that when, at 

 the site of activity, a certain degree of saturation has been reached, 

 no further effect is possible ; and certainly that no permanent effec. 

 is obtainable by repeated exhibition of the substance. Kretsch 

 mer's experiments consisted in the repetition, at regular intervals, 

 of the intravenous injection of a certain fixed quantity of adrenalin. 

 They showed that, although the same hypertensive effects could 

 be produced successively and as frequently as desired, a permanent 

 rise in blood-pressure was not obtainable by the non-continuous 

 exhibition of adrenalin, however large the doses. It is evident 

 from this that, in the case of adrenalin, unlike that of muscarin, 

 there is no cessation of absorption on the part of the specific cells, 

 and that a condition of chemical balance does not obtain. 



A permanent increase in blood-pressure, lasting for three 

 hours, was, however, obtained by the continuous transfusion of 

 adrenalin, the velocity being maintained at .00001 to .00002 grm. 

 per minute.* The hypertensive action increases the velocity of 

 the transfusion up to a certain maximal point, beyond which the 

 increase in velocity does not produce a further rise in blood- 

 pressure. Interruption in the flow of the adrenalin is followed 

 by a return of the blood-pressure to the normal, while the duration 

 of the after-affects will be in proportion to the amount of adrenalin 

 present in the blood at the moment of interruption. In view of 

 the fact that the action of adrenalin lasts only as long as the 

 substance is present in the blood, Kretschmer believes that 

 adrenalin acts as an irritant poison, and that the method of action 

 is, up to a certain point, similar to that of muscarin, the action 

 in both cases depending upon the difference between the con- 

 centration in the blood and the concentration in the cytoplasm. 

 Adrenalin differs from muscarin, however, in that the balance 

 between the two concentrations, which takes place in the case of 

 muscarin, is absent in the case of adrenalin. The disturbance of 

 balance is probably due to the continued rapid destruction of 

 adrenalin which goes on in the interior of the cell. 



What is known concerning the action of adrenalin upon the 

 vessels applies equally, as Ritzmann pointed out, to its glycosuric 

 action. Observation of the method by which adrenalin produces 

 glycosuria supplies certain data concerning the physiological 

 significance of this substance. These suggest that the continuous 

 flow of adrenalin, producing a condition of physiological adrena- 

 linasmia, may exercise an immense influence upon the permanent 

 tone of organs with a sympathetic innervation, more particularly 

 upon the vascular tone and upon the sugar tone (Zuckertonus). 



* By continuous transfusion of very dilute suprarenal extract I suc- 

 ceeded in obtaining and demonstrating (1895) a protracted vaso-contraction, 

 so that the blood-pressure which, after destruction of the entire spinal cord, 

 had fallen almost to zero, rose to 160 mm. Hg. and remained at this level 

 for several hours. 



