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  • Title: Tissue phylloquinone and menaquinones in rats are affected by age and gender.
    Author: Huber AM, Davidson KW, O'Brien-Morse ME, Sadowski JA.
    Journal: J Nutr; 1999 May; 129(5):1039-44. PubMed ID: 10222397.
    Abstract:
    Phylloquinone and ten menaquinones (MK-1-MK-10) were measured in liver and eight extrahepatic tissues from male and female rats at 3, 12 and 24 mo of age. Phylloquinone and menaquinones showed characteristic tissue distribution. In liver, all 11 vitamers of vitamin K assayed were present in varying concentrations with phylloquinone and MK-6 the major forms. The only forms of vitamin K found in extrahepatic tissues were phylloquinone, MK-4 and MK-6. Brain contained only MK-4 and traces of phylloquinone. No significant gender difference was observed for phylloquinone except in heart at 3 mo of age (P </= 0.05). In heart, kidney and brain, MK-4 was significantly higher in females than in males (P </= 0.05). A similar gender effect was seen in kidney and lung for MK-6 (P </= 0.05). With age, hepatic phylloquinone and MK-6 significantly increased (P </= 0.05), whereas MK-4 was unchanged. In extrahepatic tissues, MK-4 decreased with age in heart and kidney of males and females, and in lung and cerebellum of males (P </= 0.05). MK-6 decreased with age in all extrahepatic tissued tested (P </= 0.05). The results suggest that in extrahepatic tissues, certain menaquinones may be the predominant form of vitamin K. The specific tissue distribution and the general decline of MK-4 and MK-6 in extrahepatic tissues during aging suggest a vitamin K tissue dynamic that is affected not only by diet, but also by gender, age and the specific roles of phylloquinone, MK-4 and MK-6 in metabolism. All of these factors must be taken into account in establishing the nutrient requirement for vitamin K.
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