Role of uteroferrin in placental iron transport in swine: relationship between uteroferrin levels and iron deposition in the conceptus during gestation.

This study was to examine the relationship between uteroferrin and Fe, and Fe and Cu in the fetal pig. In Exp. 1, conceptus tissues and fluids were obtained on d 30, 45, 60, 75 and 90 of gestation for Fe and Cu analyses. In fetus minus liver, total Fe and Cu increased constantly between d 30 and 90, but Fe and Cu concentrations (microgram/g dry tissue) both decreased between d 30 and 45 and then remained relatively constant to d 90. For fetal liver, total Fe increased from d 30 (27 micrograms) to d 90 (3,222 micrograms), as did total Cu (14 micrograms on d 30 to 960 micrograms on d 90). Fetal liver Fe concentration (microgram/g dry tissue) decreased from d 30 (1,021) to d 60 (472) and then increased to d 90 (1,082), whereas Cu concentration increased between d 30 (537) and 60 (830) and then decreased between d 60 (471) and 90 (329). In allantoic fluid, both total Fe and Cu increased between d 30 and 60 and then decreased to d 90. Data from this study indicated a close temporal relationship between Fe and Cu in the fetal tissues and fluids examined. In Exp. 2, the relationship between Fe and uteroferrin in fetal tissues and fluids was studied. Uteroferrin, measured indirectly by acid phosphatase activity and Fe in fetal tissues and fluid underwent closely related temporal changes between d 30 and 112 of gestation. Changes in total Fe and Fe concentration during gestation were similar to those described for Exp. 1 in fetus minus liver, fetal liver and allantoic fluid. In addition, total Fe and Fe concentration in placental and endometrial tissues were analyzed. It was concluded that uteroferrin provides a major source of Fe in endometrial secretion and that it may be stored in placental and endometrial tissues. The relationship between Fe and Cu in conceptus tissues and erythropoiesis also is discussed.