The placental and mammary transport of [14C]menaquinone-4 in rats.
The transfer of menaquinone-4 (vitamin K2(20] to the fetus and milk was studied in pregnant and lactating rats, respectively, after oral administration (4 mg/kg) of [3'-14C]menaquinone-4. Intestinal absorption of menaquinone-4 was rapid and the highest level of radioactivity in each tissue except guts of fetal rats was observed at 4h after dosing. The level in the fetal homogenate was low. At that time, the concentration of menaquinone-4 in the fetal liver was 84 ng/g, corresponding to 9% of the value found in the placenta. Therefore, we conclude that the transfer of menaquinone-4 to the developing rat fetus is restricted by the blood-placenta barrier, but that a sufficient amount of menaquinone-4 (more than the essential amount of vitamin K to ensure full carboxylation) can be transferred into the fetal liver. It was also observed that the radioactivity was transferred to milk after oral administration to lactating rats. Milk/blood concentration ratios at 6 and 24h after dosing were 13.8 and 65.1, respectively. The elimination half-life of radioactivity in milk was about 17h. Eighty-four percent of milk of radioactivity was due to menaquinone-4. These results suggest that the prophylactic maternal oral administration of menaquinone-4 may be efficacious for a prophylaxis of neonatal and infantile vitamin K deficiency.
Tadano
K
K
Tsukuba Research Laboratories, Eisai Co., Ltd., Japan.
Yuzuriha
T
T
Miyake
Y
Y
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects / Q000528:radiation effects; D005260:Female; D005333:Fetus / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D008431:Maternal-Fetal Exchange / Q000187:drug effects*; D008892:Milk / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D010920:Placenta / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D011247:Pregnancy; D051381:Rats; D014018:Tissue Distribution / Q000187:drug effects / Q000528:radiation effects; D014812:Vitamin K / Q000031:analogs & derivatives / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D024482:Vitamin K 2 / Q000031:analogs & derivatives; D014916:Whole-Body Irradiation
D024482:Vitamin K 2; D014812:Vitamin K; C030814:menatetrenone