Placental transfer and body distribution of nickel chloride in pregnant mice

Placental transfer and body distribution of NiCl₂ were studied in pregnant mice (ICR strain, 12–14 weeks old). A single injection of NiCl₂ (4.6 mg/kg as Ni ip) was administered on the 16th day of gestation. Animals were killed at intervals of 2, 4, 6, 8, 10, 24, 30, and 48 hr after the injection and tissues were obtained for measurement of nickel concentration. Concentration of nickel in blood and placentas were found to be at maximum level (19.8 and 3.9 μg/g) 2 hr after injection, and those in liver, spleens, and kidneys reached maximum levels of 4.9, 1.3, and 56.2 μg/g, respectively, 4 hr after injection. Maximum concentration in fetal tissues (1.1 μg/g) was reached 8 hr after injection, and a slight gradual decrease was observed during 24 hr. Thereafter, there was a rapid decrease. The relative concentrations of Ni in blood, organs, and tissues of pregnant mice at 24 hr after injection were found in order from highest to lowest concentration: Kidneys > blood > placentas > fetuses ? liver > spleen. It is estimated that the Ni will be excreted in about 42 to 84 hr after injection from the calculated biological half-times.