Proline Uptake into Equine Placental Microvillous Membrane Vesicles

To study changes in L-proline uptake at different stages of gestation in mares, L-proline uptake into the maternal-facing microvillous plasma membrane was examined. The placental microvillous membrane vesicles (PMV) were isolated at three stages of gestation (6th, 8th and 10th month), characterized for their purity, and measured L-proline uptake. The uptake of L-proline into the PMV was demonstrated in a sodium-dependent manner. From apparent Km and Vmax values, it was considered that the degree of L-proline uptake by the active transport mechanism in the equine placenta tended to be higher at the 8th month than at the 6th and 10th month of gestation. These results suggest that the changes in L-proline uptake at different stages of gestation might be related to fetal growth in mares.