942 
for a diminished adrenalin action — after the mechanism indicated by H. Borner 
(see supra). — It seems to us unlikely, however, that this is the case in our 
experiments, since even a very considerable deprival of blood, by which after 
injection of Tyrode-solution the viscosity of the blood has much diminished, does not 
produce a weakened adrenalin action sometimes (Exp. 2), whereas conversely, when 
a phase has been reached in which the adrenalin acts no longer, 10 ce: of serum, 
which will increase the viscosity only slightly, sometimes improve the adrenalin 
action. It appeared thus that considerable changes in the viscosity often involved 
no change in the adrenalin action, whereas such a change did occur in a case in 
which the viscosity could be influenced only in a small measure. 
We presume to assert that especially this case, in which inactivity 
of the adrenalin resulted from the plasmaphaeresis and in which 
adrenalin action revived after the injection of serum, strongly favours 
our conception that substances occur in the serum which intensify 
the adrenalin action. It would be worth while to make more expe- 
riments on the action of adrenalin after plasmaphaeresis. Failing 
the opportunity of obtaining a large enough number of cats we 
have as yet not been able to do so. We purpose to extend our 
experimentation and, in connection with the researches of Kraus, 
FRIEDENTHAL, Krpinow ete, we also intend to study the influence 
exerted by the organs of internal secretion on the sensitivity of 
animals to adrenalin. 
CONCLUSION. 
The action of adrenalin on the bloodpressure does not only depend 
on the volume of the dosis, the velocity of the injection and the 
sensitiveness of the reacting organs, but is also influenced by sub- 
stances in the blood that intensify this adrenalin action. 
In some animals there is apparently a considerable deficiency of 
these substances (the cat of fig. 1). In them the sensitivity can be 
increased by injecting human serum or cat’s serum. Other animals 
(most cats) possess a sufficient quantum of intensifying substances, 
but this quantum can be raised by injecting Witte’s peptone or its 
dialysate. Most rabbits have so much of these substances in their 
blood, that peptone cannot increase the reaction to adrenalin. In 
one case only (Fig. 4), in which a rabbit was little sensitive to 
adrenalin, could this sensitiveness be increased by peptone. 
Utrecht, The Pharmacological Institute of the 
January 1920. Utrecht University. 
