The charge-dependent materno-fetal barrier in the rat.

The charge-dependent materno-fetal barrier of near-term rats was examined with two pairs of radiolabelled proteins differently charged. When the proteins were injected intra-arterially, the maternal blood concentrations of the two cationized proteins (BSA and human IgG) exceeded those of native proteins in the chorioallantoic placenta and fetus during the period of examination (15-180 min). In the yolk sac placenta, these percentages were essentially the same as those of native proteins. Following intra-placental injection, the amounts of the cationized proteins in the chorioallantoic placenta and fetus were significantly (p less than 0.01) greater than those of native proteins at the particular times examined (5 and 60 min). In contrast, the amounts of cationized proteins in the yolk sac placenta were basically the same as those of native proteins. The data presented above indicate the charge on proteins that considerably influenced their materno-fetal transfer, particularly via the chorioallantoic placenta.