Tissue‐Specific Proportions of Phylloquinone to Menaquinone‐4 Concentrations Differ in Response to Dietary Phylloquinone Manipulation in Lean Male Zucker Rats

Phylloquinone (PK) and menaquinone (MK) are naturally‐occurring forms of vitamin K (VK).There is selective tissue distribution and conversion of dietary PK to MK4, providing indirect evidence of unique MK4 functions beyond those established for PK. We determined the effect of dietary PK manipulation on the ratio of PK:MK4 in tissues of male lean Zucker rats (n=24, 4mo). Rats were pair‐fed a PK‐supplemented (S) (10±0.5 mg PK/kg) or PK‐deficient (D) (0.03±0.003 mg PK/kg) diet for 12 weeks. PK was the sole dietary VK form provided. Liver, kidney, brain, pancreas, mesenteric adipose tissue, serum and diet PK and MK4 concentrations were measured by HPLC. Data were analyzed by ANOVA, with p<0.01 considered significant based on a Bonferroni adjustment. Data presented as mean±SD. PK:MK4 was significantly higher in kidney, liver and mesenteric adipose tissue on the S diet (1.41±0.14 ; 78.8±15.5 and 21.8±4.8 pmol/g, respectively) compared to D diet (0.54±0.3, 7.4±4.9 and 12.2±5.4 pmol/g, respectively) (p<0.01). In contrast, PK:MK4 in brain (0.34±0.03, S; 0.55±0.3, D) and pancreas (0.86±0.3, S; 0.87±0.26, D) did not significantly differ between diet groups (both p>0.147). PK supplementation resulted in an increase in PK:MK4 in liver, kidney and adipose tissue. In brain and pancreas, tissues that have a preferential conversion of PK to MK4, there was concomitant increase in MK4 such that the PK:MK4 ratio is maintained. The implications of this ratio merits further investigation in order to elucidate the roles of MK4. Support: USDA ARS under Cooperative Agreements No. 58‐1950‐7‐707; NIH/NIDDK T32 DK062032