Placental transfer of calcium (Ca) and phosphorus (Pi) in the guinea pig: lack of correlation with placental Ca-ATPase and alkaline phosphatase (AP) activities.

In summary, it has been observed that in vitro inhibitors of placental Ca-ATPase and AP activities (EA, F, D-pen) and activators of placental AP (EA,F) are not associated with changes in Ca and Pi transfer across the in situ perfused guinea pig placenta. Assuming that the two enzyme activities were altered in vivo by these drugs, it may be that they are not directly related to active transport of Ca and Pi across the placenta.