title: Effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats: enhancement with zinc.
abstract: The effect of vitamin K2 (menaquinone-7) on bone metabolism in the femoral-metaphyseal tissues of normal and skeletal-unloaded rats was investigated. Skeletal unloading was designed using a model of hindlimb suspension; the rats were fed for the 4 days of unloading. The metaphyseal tissues obtained from normal and skeletal-unloaded rats were cultured for 48 h in medium containing either vehicle or vitamin K2 (10(-6) and 10(-5) M). The presence of vitamin K2 (10(-5) M) caused a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal rats. Such an effect was not seen in the bone tissues from skeletal-unloaded rats. Additionally, the presence of zinc sulfate (10(-5) M) in effective concentration produced a significant increase in alkaline phosphatase activity and calcium content in the metaphyseal tissues from normal and skeletal-unloaded rats. In the presence of vitamin K2 (10(-5) M), the stimulatory effect of zinc sulfate on bone calcium content was appreciably enhanced; although this effect was completely abolished by cycloheximide (10(-6) M), an inhibitor of protein synthesis. This study demonstrates that the effect of vitamin K2 (menaquinone-7) on trabecular bone calcification in rats with skeletal unloading-induced osteopenia is enhanced by zinc in vitro. The enhancement with zinc may be based on a newly synthesized protein in the bone tissues.
authors.affiliation: Laboratory of Endocrinology and Molecular Metabolism, Graduate School of Nutritional Sciences, University of Shizuoka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ehara
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Hanahisa
authors.forename: M
authors.initials: M
authors.lastname: Yamaguchi
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D018488:Bone Demineralization, Pathologic / Q000188:drug therapy / Q000517:prevention & control; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004347:Drug Interactions; D005260:Female; D005269:Femur / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D007103:Immobilization / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014812:Vitamin K / Q000031:analogs & derivatives* / Q000494:pharmacology; D024482:Vitamin K 2 / Q000031:analogs & derivatives*; D016474:Weight-Bearing / Q000502:physiology; D015032:Zinc / Q000494:pharmacology*
chemical_list: D011500:Protein Synthesis Inhibitors; D024482:Vitamin K 2; D014812:Vitamin K; C062629:menaquinone 7; D004247:DNA; D003513:Cycloheximide; D000469:Alkaline Phosphatase; D015032:Zinc; D002118:Calcium