Phylloquinone transport and its influence on γ-carboxyglutamate residues of osteocalcin in patients on maintenance hemodialysis

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Abstract
Plasma concentrations of phylloquinone in 42 fasting hemodialysis patients showed a much wider range than in healthy adults. Phylloquinone concentrations were best predicted by the concentration ratio of β-very-low-density-lipoprotein to low-density-lipoprotein cholesterol (r = 0.71), which is closely related to chylomicron-remnant clearance. Phylloquinone concentrations in plasma were related to apolipoprotein E genotype in the order E2 > E3 > E4. The percentage of carboxy lated osteocalcin (HBC) was related to the plasma concentration of phylloquinone in patients with the apolipoprotein E genotype E3/3 (r = 0.52, P < 0.05), and in patients with the genotypes E2/3 and E2/2 (r = 0.23, P < 0.1). Overall, plasma triglyceride concentration was a better predictor for HBC than was the plasma concentration of phylloquinone. These results point to the overriding importance of chylomicrons for the transport of phylloquinone to liver and bone. Delivery to osteocalcin-producing osteoblasts seemed impaired in patients with the low receptor-affinity apolipoprotein variant E2, suggesting a major role of receptor-mediated chylomicron-remnant uptake in the transport of phylloquinone to bone.