Disruptions in amino acid metabolism are well-known in
HIV(þ) adults both taking and not taking cART [17e19], however,
little is known regarding maternal amino acid metabolism during
HIV(þ) pregnancy and its potential effects on infant birth weight
and cardiac function. Based on previous findings of insulin resistance
[20,21] and impaired fatty acid oxidation [22] in non-gravid
HIV(þ) adults, we hypothesized that maternal leucine utilization
(i.e. oxidation rate) during HIV(þ) pregnancy would be higher in
order to meet maternal energy needs (i.e. to compensate for insulin
resistance and lower fatty acid oxidation) leaving less leucine (i.e.
lower plasma concentration and leucine non-oxidative disposal
rate) available for fetal growth and metabolism. Subsequently,
reduced maternal amino acid delivery to the fetus could contribute
to lower birth weight and cardiac function in the offspring by
limiting the amount of leucine or by disrupting growth signaling needed for fetal organ growth and maturation. Therefore, our primary
aim was to compare post-absorptive maternal leucine kinetics
in late pregnancy between women with and without HIV
taking cART. Our secondary aim was to examine the relationships
between maternal post-absorptive leucine kinetics and infant birth
weight and cardiac function. We also measured maternal glucose
and fatty acid kinetics in order to examine leucine kinetics in the
context of overall maternal substrate metabolism. Identification of
mechanisms for abnormalities in infant body composition and
cardiac structure and function in children exposed to HIV and cART
may lead to nutritional optimization strategies for HIVþ pregnancy;
especially important in resource limited countries and in
those who are socio-economically disadvantaged, where nutrition
is often sub-optimal.