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 mot her 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 m aternal vitamin D deficiency altered the well characterized developmen t of the neonatal heart. Weaned rat pups (21-day-old) were obtained fr om 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. Thes e pups were sacrificed, hearts excised, and the hearts biochemically a nalysed 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 mu mol/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 mu mol g(-1) min(-1), and 3 -hydroxyacyl CoA dehydrogenase activity (59 v 91 mu mol g(-1) min(-1)) . Hexokinase activity (1.98 v 2.02 mu mol g(-1) min(-1)), and the dist ribution of cardiac myosin among its three isoforms (>85% V1), were un affected by this dietary deficiency, however myofibrillar protein cont ent 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.