Affiliations: Research Institute for Electronic Science, Hokkaido University, North 12, West 6, North District, Sapporo 060‐0812, Japan
Note: [] Correspondence to: Takeru Naiki, Research Institute for Electronic Science, Hokkaido University, N‐12 W‐6, North District, Sapporo 060‐0812, Japan. Tel.: +81 11 706 3369; Fax: +81 11 706 4975; E‐mail: naiki@ bfd.es.hokudai.ac.jp.
Abstract: The effect of steady shear flow on concentration polarization of plasma proteins and lipoproteins at the luminal surface of a semipermeable vessel wall was studied experimentally using suspensions of these molecules in a cell culture medium and a semipermeable membrane dialysis tube which served as a model of an implanted vascular graft or an artery. The study was carried out by flowing a cell culture medium containing fetal calf serum or bovine plasma lipoproteins or bovine albumin through a 7.5 mm diameter, 60 mm‐long dialysis tube in steady flow under a physiologic mean arterial perfusion pressure of 100 mmHg, and measuring the filtration velocity of water (cell culture medium) at the vessel wall which varied as a consequence of the change in concentration of plasma protein particles at the luminal surface of the semipermeable membrane dialysis tube. It was found that for perfusates containing plasma proteins and/or lipoproteins, filtration velocity of water was the lowest in the absence of flow, and it increased or decreased as the flow rate (hence wall shear rate) increased or decreased from a certain non‐zero value, indicating that surface concentration of protein particles varied reversibly as a direct function of flow rate. It was also found that at particle concentrations equivalent to those found in a culture medium containing serum at 5% by volume, plasma lipoproteins which were much smaller in number and lower in concentration but larger in size than albumin, had a much larger effect on the filtration velocity of water than albumin. These findings were very much the same as those previously obtained with a cultured endothelial cell monolayer, strongly suggesting that the flow‐dependent variation in filtration velocity of water at a vessel wall results from a physical phenomenon, that is, flow‐dependent concentration polarization of low density lipoproteins at the luminal surface of the endothelial cell monolayer.
