COMPARATIVE METABOLISM OF PHYLLOQUINONE AND MENAQUINONE-9 IN RAT-LIVER

The hepatic turnover of phylloquinone and menaquinone-9 (MK-9) and the ir relative efficacy in satisfying the dietary requirement for vitamin K were compared in male rats. Rats fed 1.1-mu-mol phylloquinone/kg di et had higher initial liver and serum vitamin K concentrations than ra ts fed an equimolar amount of MK-9. The initial rate of hepatic turnov er of phylloquinone was two to three times as rapid as that of MK-9. A fter about 48 h of vitamin K restriction there were no significant dif ferences in hepatic vitamin K concentration of rats fed phylloquinone or MK-9. Phylloquinone was much more effective than MK-9 in maintainin g normal vitamin K status at low dietary concentrations (0.2-mu-mol/kg diet), whereas at high dietary concentrations (5.6-mu-mol/kg diet) th ey were equally effective.