a n d P a u l Hamosh. (Spon. b y Gordon B . A v e r y ) Georgetown U n i v e r s i t y Medical C e n t e r , d e p t s . of P e d i a t r i c s a n d Physiology a n d B i o p h y s i c s . Washington DC .We h a v e r e c e n t l y s h o w n t h a t a d m i n i s t r a t i o n of p r o l a c t i n ( 1 m g p e r f e t u s ) to r a b b i t f e t u s e s l e a d s to a n i n c r e a s e in t h e concentration of l u n g dipalmitoyllecithin ( Hamosh, J . Clin. I n v e s t . 59: 1002,1977 In t h e p r e s e n t s t u d y w e h a v e t e s t e d t h e r e l a t i o n s h i p between s e r u m prolactin a n d c o r t i s o l l e v e l s a n d lung m a t u r i t y in p r e m a t u r e i n f a n t s .Prolactin a n d c o r t i s o l l e v e l s w e r e m e a s u r e d b y radioimmunoassay i n 40 p r e m a t u r e i n f a n t s b e t w e e n 26 a n d 37 w e e k s of gestation. Mixed c o r d blood w a s collected a t d e l i v e r y , c e n t r i f u g e d a n d t h e s e r a k e p t a t -20% u n t i l analysis. Prolactin l e v e l s r a n g e d from 20 to 600 n g / m l c o r t i s o l l e v e l s m e a s u r e d 25 to 350 n g / m l . C o r d p r o l a c t i n l e v e l s l e s s t h a n 140 n g l m l w e r e a s s o c i a t e d with a h i g h i n c i d e n c e of r e s p i r a t o r y d i s t r e s s s y n d r o m e (RDS); of 18 i n f a n t s with p r o l a c t i n l e v e l s less t h a n 140 n g l m l 16 (89%) h a d RDS. Only 27% of t h e i n f a n t s with RDS h a d p r o l a c t i n l e v e l s a b o v e 140 n g l m l . Two of t h e h i g h e s t l e v e l s i n t h i s g r o u p w e r e from infants with d i a b e t i c m o t h e r s . T h e r e w a s n o c o r r e l a t i o n b e t w e e n c o r d s e r u m p r o l a c t i n a n d c o r t i s o l l e v e l s or b e t w e e n c o r t i s o l l e v e l s a n d t h e i n c i d e n c e of RSD. T h e data s u g g e s t t h a t p r o l a c t i n might b e a t r i g g e r of l u n g maturation i n t h e h u m a n f e t u s . A t o t a l of 26 l i t t e r s were s t u d i e d . F e t u s e s from s a l i n e -i n j e c t e d c o n t r o l and d i a b e t i c l i t t e r s were examined a t 27.5 and 29.5 days g e s t a t i o n a l age. Pressure-volume c u r v e s were performed and s u rf a c t a n t from a l v e o l a r lavage f l u i d was q u a n t i f i e d on a s u r f a c e balance.Blood s u g a r s of d i a b e t i c does ranged from 175-400 mg/d throughout pregnancy a s compared w i t h 80-120 mg/dl i n t h e cont r o l s . :! P e d i a t r i c : and Medi--c i n e , C o l l . of Phys. and S u r g . , Columbia U n i v e r s i t y , New York. Fed. Proc. 36:630, 1977). To s t u d y t h e c e l l u l a r b a s i s of t h i s phenomenon, we h a r v e s t e d e n d o t h e l i a l c e l l s by p e r f u s i n g hu man umbilical c o r d s , r a b b i t and pig lungs and c a l f a o r t a s w i t h m i x t u r e of 0.1% c o l l a g e n a s e , 0.1% t r y p s i n and 1.0% chicken seru i n Hank's S o l u t i o n , and propagated t h e c e l l s i n medium 199. CE a c t i v i...