296  Chemistry  of  Pressor  Compounds.  {Am'j^yri9Harm' 
made  from  these  organs  usually  enhanced  the  depressor  action  and 
masked  the  pressor  effects.  Miller  and  Miller  found  that,  by  auto- 
clave treatment,  the  pressor  action  of  pituitary  extracts  disappeared, 
while  the  depressor  persisted. 
It  has  been  shown  21  that  in  cats  the  injection  of  extracts  of 
pituitary  glands,  taken  from  almost  any  vertebrate  animal,  will 
increase  the  urinary  secretion.  This  action  has  been  claimed  by 
some  22  to  be  due  to  its  pressor  principle,  but  there  is  physiological 
evidence  to  show  that  the  diuretic  and  pressor  actions  are  due  to 
separate  constituents.  This  diuretic  action  is  confined  to  the  pos- 
terior lobe,  and  second  injections  of  such  extracts  do  not  produce 
tolerance  to  its  diuretic  effect,  but  rather  increase  its  action.  Ex- 
tracts of  pituitary  glands  taken  from  some  animals  have  little  or 
no  effect  on  blood-pressure,  yet  exert  a  diuretic  action.23 
It  has  been  found  that  extracts  of  pituitary  glands  exert  an 
action  on  various  organs  which  are  supplied  with  unstriated  muscles, 
such  as  the  uterus,24  intestines,  bladder,  etc.  Recently  Barger  and 
Dale  have  shown  that  various  amines  will  not  only  produce  a  rise 
in  blood-pressure,  but  also  affect  various  organs  with  unstriated 
muscles.  In  this  case  the  action  is  on  the  extreme  terminals  (re- 
ceptor bodies)  of  the  sympathetic  nerves  supplying  these  organs, 
and  these  observers  have  designated  this  action  as  "  sympathomi- 
metic." In  the  case  of  the  pituitary  extracts  the  action,  at  least  on 
the  uterus,  seems  to  be  different,  and  is  believed  by  Dale  to  be  on 
the  muscles  rather  than  on  the  sympathetic  nerve-endings.  This 
view  is  supported  by  the  experiments  of  Paton  and  Watson  on 
birds. 
The  pressor  principle  and  the  one  which  causes  uterine  contrac- 
tions may  not  necessarily  be  the  same,  or,  at  least,  all  of  the  uterine 
21  Schaefer,  E.  A.,  and  Herring,  P.  T.,  "  Action  of  Pituitary  Extracts 
upon  the  Kidney,"  Philos.  Trans.  Roy.  Soc.  London,  Ser.  B,  vol.  199,  p.  1 
(1908). 
22  Houghton,  E.  M.,  and  Merrill,  C.  H.,  "  Diuretic  Action  of  Adrenalin 
and  the  Active  Principle  of  the  Pituitary  Body,"  Jour.  Amer.  Med.  Assoc., 
vol.  51,  p.  1849  (1908). 
23  Herring,  P.  T.,  "  Further  Observations  upon  the  Comparative  Anatomy 
and  Physiology  of  the  Pituitary  Body,"  Quart.  Jour.  Exper.  Physiol.,  vol.  6, 
P-  73  (1913). 
24  Bayer,  G.,  and  Peter,  L.,  "  Zur  Klenntniss  des  Neurochemismus  der 
Hypophyse,"  Arch.  f.  exper.  Path.,  vol.  64,  p.  204  (1911). 
