746 
PHARMACOLOGY 
lamines may play a more critical, compensatory 
role in maintaining ventricular contractility 
than in the adult. In adult animals, it is evident 
that only a small fraction of the normal cardiac 
stores of norepinephrine is necessary to elicit a 
functional response to adrenergic nerve 
stimulation^- or tyramine,^^ although the mag- 
nitude and perhaps the duration of the response 
may be reduced. -° 
SUMMARY 
It is clear that a more complete understand- 
ing of the normal development of the heart and 
autonomic influences is necessary to provide a 
framework within which the effects of a variety 
of disease states can be elucidated. Further, it is 
apparent that in addition to looking for differ- 
ences in drug metabolism and disposition in the 
immature organism the altered responses of 
fetal and neonatal myocardium per se must be 
considered in any evaluation of cardiac pharma- 
cology in the perinatal period. Surely, it will be 
necessary to integrate analyses of all of these 
factors if we are to create a scientific frame- 
work for the rational, clinical approach to dis- 
ease states encountered in the premature and 
newborn infant. 
ACKNOWLEDGMENTS 
A number of individuals have participated in 
a major way in various aspects of these studies, 
including Dr. Charles Cooper, Dr. David Jaco- 
bowitz, Dr. Peter Pool and Mrs. Shirley Sea- 
gren. I'm especially grateful to Dr. Eugene 
Braunwald for creating an environment in 
which the highest priorities exist for the ad- 
vancement of the cardiovascular sciences. 
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