MATURATION OF THE SULFOBROMOPHTHALEIN SODIUM-GLUTATHIONE CONJUGATING SYSTEM IN RAT LIVER*

Abstract

The BSP-glutathione conjugating system was examined in livers obtained from rat fetuses, in utero, and at various stages of development after delivery. BSP-glutathione conjugating enzyme activity of fetal liver was very low in the few days before birth, then rapidly increased 2.5- to 10-fold to approximately 50% adult activity by the 3d postpartum day. Thereafter it increased gradually, reaching adult levels by 5 to 7 weeks after delivery. Conjugating enzyme activity in maternal liver was also depressed prior to term, then rapidly increased soon after delivery. The concurrent depression of fetal and maternal enzyme activity during the latter part of gestation, followed by a rapid increase in activity in the early postpartum period, suggests the presence of an enzyme inhibitor in pregnancy that disappears after delivery. No evidence was found of an enzyme inhibitor in fetal liver or of enzyme activator in adult liver. Hepatic glutathione concentration of young rats were reduced to approximately 50 to 60 per cent of adult levels in the few days before and for 3 weeks after delivery. Thereafter it reached adult levels. Glutathione levels of maternal liver obtained before and after term remained within the adult range. The data suggest that delayed BSP clearance from blood observed in the human premature and full-term infant may be due, at least in part, to inadequate development of the BSP-glutathione conjugating system. Improved BSP clearance with increasing age could be explained by maturation of the conjugating mechanism.