PHYLLOQUINONE AND MENAQUINONE-4 DISTRIBUTION IN RATS - SYNTHESIS RATHER THAN UPTAKE DETERMINES MENAQUINONE-4 ORGAN CONCENTRATIONS

To clarify the origin of organ menaquinone-4 (MK-4), the distributions of phylloquinone and MK-4 were investigated in rats fed diets contain ing phylloquinone, MK-4 or menadione (1.1, 2.2 and 31 mu mol/kg diet, respectively, 6 rats per group). Warfarin (2 x 1 mg/kg subcutaneously) was given (3 rats per group) to study the effect of vitamin K cycle b lockage. In rats fed phylloquinone the vitamin accumulated mainly in l iver and heart. Additionally, the diet resulted in significantly highe r organ MK-4 concentrations compared with the vitamin K-deficient cont rols. The epoxide of MK-4 also was significantly higher in some organs . The MK-4 diet increased MK-4 concentration primarily in the heart, l iver and lung. Rats fed menadione had significantly higher MK-4 and MK -4 epoxide concentrations in all organs examined. The greatest accumul ations were in nonhepatic organs, particularly the pancreas, salivary gland and brain. Generally, liver and plasma had low MK-4 concentratio ns. Warfarin treatment lowered Significantly the MK-4 concentrations, whereas MK-4 epoxide accumulated. The study shows the following: 1) di etary phylloquinone is accumulated mainly in the heart and liver, 2) t he MK-4 accumulation in nonhepatic organs is due to synthesis rather t han uptake and 3) MK-4 rather than phylloquinone may be the functional vitamin in nonhepatic organs.