^bltob^^iT  ^    Specificity  of  Drugs  for  Phosphatids. 
441 
not  account  for  direct  specificity  of  drug  action  in  the  brain  and 
heart,  it  might  be  that  cephalin  and  cuorin  would.  Lecithin  from 
the  heart  may  be  identical  with  brain  lecithin  but  cuorin  is  not  the 
same  as  cephalin. 
Though  they  were  repeatedly  experimented  with  as  above  described 
for  lecithin,  they  gave  results  which  indicated  that  the  drugs  affected 
cuorin  and  cephalin  much  as  they  do  the  lecithins.  There  were  no 
indications  that  specificity  was  due  to  them.  However,  because  of 
the  rather  unsatisfactory  end  points  the  results  with  these  two  phos- 
phatids are  not  very  conclusive. 
CONCLUSIONS. 
1.  Drugs  do  affect  the  auto-oxidation  of  lecithin.  One  of  the 
ways  in  which  some  specificity  may  exist,  then,  is  in  the  alteration 
in  tissue  oxidation. 
2.  Though  certain  compounds  (principally  the  heart  drugs)  do 
combine  with  heart  lecithin,  there  is  no  direct  specificity,  because 
they  affect  brain  lecithin  in  the  same  way.  This  would  indicate  that 
the  peculiar  action  of  these  drugs  was  due  to  an  effect  on  the  com- 
plexes in  the  cell  itself,  not  on  the  phosphatid,  but  that  the  lipins 
in  the  surface  layer  of  the  tissue  cells  may  determine  the  amounts  of 
the  drug  that  will  enter. 
3.  The  precipitation  limits  of  calcium  chloride  on  lecithin  solu- 
tions are  different  when  different  salts  of  the  drug  are  present.  It 
is  necessary,  then,  in  a  comparative  study  to  use  the  free  alkaloids. 
4.  The  higher  the  drug  concentration,  the  greater  the  amount  of 
combination  with  the  lecithin. 
5.  Heart  cuorin  and  brain  cephalin  give  no  indication  of  being 
more  related  to  specificity  than  the  lecithin. 
From  the  Biochemical  Laboratories  of 
the  Universities  of  Chicago  and  Illinois. 
