Gender differences in hepatic phylloquinone and menaquinones in the vitamin K-deficient and -supplemented rat

Gender differences in relation to vitamin K were investigated in the rat. H epatic phylloquinone and menaquinone (MK-1 to MK-10) concentrations, gamma- carboxyglutamic acid (Gla) excretion, plasma phylloquinone and percent prot hrombin were measured in male and female rats on a chow diet (24.5 ng phyll oquinone and 8.8 mu g menadione), and on phylloquinone deficient and -suppl emented purified diets (0.38 and 1400 ng phylloquinone/g, respectively). Me an hepatic phylloquinone concentrations varied with dietary intake and rang ed from 6.8 +/- 9.0 pmol/g in the deficient male, to 171.1 +/- 56.9 pmol/g in the supplemented female. Menaquinones accounted for a large proportion o f total vitamin K in the liver of males and females with MK-4, MK-6, and MK -IO present in highest concentrations. On the chow and supplemented diets, females had significantly higher MK-4, MK-6, and MK-10 concentrations in th eir livers (P < 0.05). On the phylloquinone-deficient diet (-K-1), hepatic phylloquinone, MK-4, and to a lesser extent MK-6 (but not MK-IO) were signi ficantly reduced (P < 0.05). In the phylloquinone-supplemented male and fem ale groups, which did not receive menadione during the experimental period, MK-4 increased above that in the chow groups suggesting synthesis of MK-4 from phylloquinone which was statistically significant in the female (P < 0 .01). A significant gender difference (P < 0.05) was also observed for urin ary Gla excretion with less Gla excreted by the females indicating that fem ales may require less dietary phylloquinone than males of the same body wei ght. (C) 1999 Elsevier Science B.V. All rights reserved.