STUDIES ON PREMATURITY

This program consists of 8 projects centered around studies of perinatal
metabolism, fetal and placental growth, and cardiopulmonary adaptation.
The studies of fetal and maternal carbohydrate metabolism (Project I)
include studies in both hypo- and hyperinsulinemic states, define the
conditions for fetal gluconeogenesis and the adaptations of the maternal
liver to pregnancy. The studies in newborn lambs (II) include the relative
roles of glucose and galactose intake in glycogen synthesis and the impact
of the 2 dietary transitions on protein synthesis and turnover. The
studies of fetal amino acid metabolism (III) include the evaluation of
potential fetal growth factors, i.e. somatomedin I, growth hormone, and
insulin, upon leucine flux to CO2 and to protein synthesis, and address the
ontogenic changes in protein synthesis during early fetal life. The impact
of dietary changes in the mother on potential fetal growth factors and
protein synthetic rates will be evaluated. Project IV will study the
metabolic changes induced in the mother by labor onset. The relationship
between maternal metabolism and abnormal labor will be assessed. The
studies will also consider the potential role of the placenta as a
metabolic buffer to the fetus during labor. The possibility that the
placenta becomes hypermetabolic during labor, sparing nutrients and oxygen
for the fetus, will be investigated. The adaptations of normal and abnormal fetal pulmonary circulations and of
the transitional circulation will be studied (V) with focus on the
chronicity of the adaptive responses. Interorgan cycling of substrates
will be studied (VI) using the fetal hindlimb and liver with emphasis on
lactate kinetics. The possibility that lactate metabolism may be
relatively unregulated will be investigated utilizing lactate clamp
methodology. In Project VII, the studies of early fetal life will center
around metabolic and placental function studies performed in the
midgestation ewe when the fetus is 5%-10% of its term weight, providing far
more precise ontogenic scaling of metabolic processes to body size.
Project VIII will study the relationship between fetal and placental
growth, body composition and caloric accretion, and the rates of glycogen
and lipid synthesis. Comparisons will be made within litters for the
guinea pig and rabbit so that fetal growth and composition can be compared
in relationship to variations in placental size and perfusion.