we compared the responses of third and fourth generation pulmonary arteries to norepinephrine , epinephrine , serotonin , and kcl from lambs 7 d preterm and 1 , 7 , and 21 d of age to assess differences between age and third and fourth generations of the pulmonary arterial tree during the transitional period .
C0028351
norepinephrine
C0014563
epinephrine