Ontogenesis of tissue catecholamines in fetal and neonatal XXXX .

@entity1425 @entity1063 @entity95 @entity2922
The ontogenesis of tissue @entity2922 concentrations in heart, lung, brown adipose tissue, adrenal and para-aortic chromaffin tissue was assessed in fetal and newborn @entity95 using a radioenzymatic assay adapted to perchloric extracts of tissue. Measurements were conducted at 20, 24, 27 and 31 days gestation and at 3 and 7 days of age. Myocardial @entity1063 was detectable at 20 days gestation, the earliest age studied. Lung @entity1063 was not detectable until 24 days gestation. @entity1063 concentrations in brown adipose were similar to myocardial levels. Adrenal and para-aortic tissue @entity2922 content increased significantly between 24 days gestation and 7 days of postnatal age. @entity1425 became the predominant adrenal @entity2922 by 24 days gestation. Para-aortic body @entity1063 concentrations always were substantially less than adrenal @entity1063 or @entity1425 contents. @entity1425 was undetectable in para-aortic bodies at 20 and 24 days and at 31 days was only 27% of @entity1063 content. Adrenal maturation as reflected by @entity1425 content or @entity1425 / @entity1063 ratio correlated positively with body weight in the 31 day gestation fetuses. Thus, significant changes in tissue @entity1063 concentrations occur during the developmental time period studied. Parallel maturational changes occur in adrenal and para-aortic chromaffin tissue.
