Effect of diabetes mellitus on maternofetal flux of calcium and magnesium and calbindin9K mRNA expression in rat placenta.

The effect of maternal diabetes mellitus on placental unidirectional maternofetal flux of calcium (Ca) and magnesium (Mg), calbindin9K mRNA expression, and net fetal Ca and Mg accretion has been investigated using control (C), untreated diabetic (D(O)) and insulin-treated diabetic (DI) rats. Unidirectional maternofetal flux of Ca in the D(O) group was 61 and 63% of the value of the C and DI groups; unidirectional maternofetal flux of magnesium in the D(O) group was 79 and 66% of the value in the C and DI groups. Fetal Ca and Mg content (mmol; mean +/- SEM) was also significantly lower in the D(O) group compared with the other two groups (0.111 +/- 0.004 versus 0.153 +/- 0.008 in C and 0.168 +/- 0.007 in DI, p < 0.01 D(O) versus C and DI for Ca; and 0.021 +/- 0.001 versus 0.027 +/- 0.001 in C and 0.031 +/- 0.001 in DI, p < 0.01 D(O) versus C and DI for Mg). However, only Ca content was significantly lower in the D(O) group when normalized to fetal ash weight. Densitometric analysis of autoradiograms after Northern hybridization with cDNA probes demonstrated that the placental calbindin9K/cyclophilin mRNA ratio was 11- to 12-fold lower in the D(O) group compared with the C and DI groups. Collectively, the data suggest that untreated maternal diabetes mellitus reduces fetal Ca and Mg accretion by an effect on the expression of placental transport components involved in the maternofetal transfer of these cations.