Micelle-mediated transport of vitamin K1 through porous membranes: contribution of phosphatidylcholine-bile salt mixed micelles.

Diffusion of vitamin K1 solubilized by phosphatidylcholine-sodium deoxycholate mixed micelles through porous membranes having various pore characteristics was examined. The membranes include Nuclepore, Duragard and nitrocellulose membranes, which were intended to mimic the narrow channels in the vicinity of absorptive brush border. The diffusion coefficient of the mixed micelles was 4.6-5.5 x 10(-7) cm2/s, from which the hydrodynamic radius was calculated to be about 50 A. The dependence of the diffusivity on pore size showed that the transport of the micelles is hindered by pores having a radius ratio of the diffusate to the pore of about 0.05 or larger.