INTESTINAL FLORA IS NOT AN INTERMEDIATE IN THE PHYLLOQUINONE-MENAQUINONE-4 CONVERSION IN THE RAT

To elucidate the role of intestinal bacteria in the conversion of phyl loquinone into menaquinone-4 (MK-4) we investigated the tissue distrib ution of vitamin K in germ-free rats. The rats were made vitamin K def icient by feeding a vitamin K-free diet for 13 days. In a subsequent p eriod of 6 days, phylloquinone and menadione were supplied via the dri nking water in concentrations of 10 and 50 mu mol l(-1). Menadione sup plementation led to high levels of tissue MK-4, particularly in extrah epatic tissues Like pancreas, aorta, fat and brain. Liver and serum we re low in MK-4. Phylloquinone supplementation resulted in higher phyll oquinone levels in all tissues when compared with vitamin K-deficient values. The main target organs were Liver, heart and fat. Remarkably, tissue MK-4 levels were also higher after the phylloquinone supplement ation. The MK-4 tissue distribution pattern after phylloquinone intake was comparable with that found after menadione intake. Our results de monstrate that the conversion of phylloquinone into MK-4 in extrahepat ic tissues may occur in the absence of an intestinal bacterial populat ion and is tissue specific. A specific function for extrahepatic MK-4 or a reason for this biochemical conversion of phylloquinone into MK-4 remains unclear thus far. (C) 1998 Elsevier Science B.V.