292 
Chemistry  of  Pressor  Compounds.     {Am  j°™' ilurm" 
heart,  while  the  other  causes  a  rise  in  blood-pressure  through  inhi- 
bition of  the  depressor  nerve.4 
Howell 0  traced  the  pressor  action  of  the  pituitary  exclusively  to 
the  infundibular  portion,  and  found  that,  if  the  injection  of  extracts 
of  this  portion  were  repeated  rapidly,  the  second  injection  caused 
no  rise  in  blood-pressure  and  produced  no  cardiac  inhibition.  He 
also  found  that  extracts  of  the  anterior  lobe  usually  induced  no 
effect,  either  on  the  blood-pressure  or  on  the  heart- rate.  If  the 
vagi  were  intact,  as  in  Oliver  and  Schaefer's  original  experiments, 
extracts  of  the  infundibular  lobe  caused  a  rise  in  blood-pressure 
with  a  slow  heart-beat,  but  if  the  vagi  were  cut  there  was  a  rise  in 
pressure  with  less  slowing  than  when  the  vagi  were  intact,  hence  the 
action  is  partly  central.  Other  workers  have  found  that  some  of 
the  cardiac  slowing  is  peripheral  in  origin.6 
In  Howell's  experiments  both  sheep  and  dog  pituitaries  were 
used  and  were  tested  on  dogs.  Schaefer  and  Vincent 7  confirmed 
Howell's  conclusions  that  the  pressor  principle  was  confined  to  the 
infundibular  portion,  and  the  latter  workers  made  the  further  sug- 
gestion that  in  extracts  of  this  gland  there  was  a  depressor  com- 
pound. They  agreed  with  Howell  that  a  second  injection,  if  given 
too  soon  after  the  first,  would  cause  no  immediate  rise  in  blood- 
pressure,  but  claimed  there  might  be  a  delayed  rise  and  that  the 
second  injection  produced  a  more  marked  fall,  so  that  no  tolerance 
to  the  depressor  action  was  produced.  The  depressor  action  still 
occurred  after  the  use  of  atropin  and  was,  therefore,  not  due  to 
cholin.  Slowing  of  the  heart  was  not  constant,  but  when  present 
might  be  very  persistent. 
They  found  that  the  pressor  compound,  at  least  in  the  form  in 
which  it  existed  in  the  glands,  was  insoluble  in  alcohol  or  ether, 
while  the  depressor  body  was  soluble  in  absolute  alcohol.  Schaefer 
4  Cyon,  E.  v.,  "  Die  physiologischen  Herzgiften,"  Arch.  f.  ges.  Physiol., 
vol.  73,  p.  339  (1898). 
5  Howell,  W.  H.,  "  Physiological  Effects  of  Extracts  of  the  Hypophysis," 
Jour.  Exper.  Med.,  vol.  3,  p.  245  (1898). 
6  Hebdom,  K.,  "  Ueber  die  Einwirkung  verschiedener  Stoffe  auf  das 
isolierter  Saugetierherz,"  Skan.  Arch.  /.  Physiol.,  vol.  8,  p.  147  (1898)  ;  Cleg- 
horn,  A.,  "  Action  of  Animal  Extracts  ...  on  Mammalian  Heart 
Muscle,"  Amer.  Jour.  Physiol.,  vol.  2,  p.  273  (1899). 
7  Schaefer,  E.,  and  Vincent,  S.,  "  Physiological  Effects  of  Extracts  of  the 
Pituitary  Body,"  Jour.  Physiol.,  vol.  25,  p.  87  (1899). 
