A COMPARISON OF THE CONCENTRATION OF C14IN THE TISSUES OF PREGNANT AND NONPREGNANT FEMALE RATS FOLLOWING THE INTRAVENOUS ADMINISTRATION OF VITAMIN K1-C14AND VITAMIN K3-C14

Abstract

The Cl4 content was determined of the livers, spleens, skeletal muscle, blood, feces, and urine of both pregnant and nonpregnant female rats and of the placentas, fetal livers, fetuses, and amnionic fluids of pregnant rats following the intravenous administration of 5 mg./kg- of either vitamin K1-C14 or vitamin K3-C14. The C14 concentrations of the livers of the rats given vitamin K1 were about 24 times larger than those of animals that had received vitamin K3-C14. A fivefold difference in the same direction exists between the concentrations in the spleens of the two groups. The C14 levels for skeletal muscle, blood, placenta, fetal liver, and fetal tissue were of similar magnitude regardless of whether vitamin K1 or vitamin K3 was administered. Isotope dilution tests revealed that following intravenous administration of vitamin Kj-C14 the amount of radioactivity present as unchanged vitamin K1-Cl4 was 12% for fetal tissue, 59% for placenta, and 120% for the maternal liver. The dry weights of the livers of pregnant rats were larger than those of nonpregnant rats and the increase was proportional to the live weight of the pregnant rat. No significant difference could be demonstrated in the percentage of the injected dose of vitamin K1 deposited in the livers of pregnant or nonpregnant rats. The same was true for vitamin K3-C14. The results of this experiment indicate that vitamin K3-C14 is not concentrated in the liver of the rat whereas vitamin K3-Cl4 is. Furthermore, it would appear that both vitamin K1 and vitamin K3 can pass the placental barrier of the rat.