Maternal consumption of a low vitamin D diet retards metabolic and contractile development in the neonatal rat heart

During the fetal and suckling periods of mammalian development, the mother serves as the sole nutritional source for the offspring. As such, the quality of the maternal diet effects growth and development of the offspring during these periods. This study sought to determine if a maternal vitamin D deficiency altered the well characterized development of the neonatal heart. Weaned rat pups (21-day-old) were obtained from mothers who had consumed either a vitamin D-supplemented diet (3000 IU of vitamin D/kg) or a low vitamin D diet (<200 IU of vitamin D/kg) prior to becoming pregnant and throughout pregnancy and suckling. These pups were sacrificed, hearts excised, and the hearts biochemically analysed for metabolic and contractile protein properties. The pups of dams fed the low vitamin D diet were slightly hypocalcemic relative to those on the supplemented diet (2.28 v 2.41 μmol/l, P<0.05), had significantly lower body weights (43 v 55 g), heart weights (143 v 174 mg), citrate synthase activity (106 v 147 μmol g−1 min−1, and 3-hydroxyacyl CoA dehydrogenase activity (59 v 91 μmol g−1 min−1). Hexokinase activity (1.98 v 2.02 μmol g−1 min−1), and the distribution of cardiac myosin among its three isoforms (>85% V1), were unaffected by this dietary deficiency, however myofibrillar protein content was approximately 15% lower in the experimental hearts. These data demonstrate that maternal consumption of a low vitamin D diet results in a general but significant slowing of neonatal cardiac development.