Effect of swirling flow on the uptakes of native and oxidized LDLs in a straight segment of the rabbit thoracic aorta.

To elucidate the physiological significance of the spiral flow in the arterial system from the viewpoint of atherogenic lipid transport, an ex vivo experimental comparative study was designed to investigate the effect of swirling flow on the distribution of native 3,3'-dioctadecylindocarbocyanine-low-density lipoproteins (DiI-LDL) and DiI-ox-LDL uptakes by segments of the rabbit thoracic aorta. The experimental results showed that when compared with the normal flow, the swirling flow generated in the test arteries significantly reduced the DiI-LDL and DiI-ox-LDL uptakes by the arterial walls. The results also showed that the values of DiI-ox-LDL uptake were higher than those of DiI-LDL uptake at the same sample position in both the normal flow group and the swirling flow group. Most interestingly, the experimental results found that the percentage increase in DiI-ox-LDL uptake was much larger than that in DiI-LDL uptake when the perfusion duration increased from 3 to 24 h. In conclusion, the present study substantiated the hypothesis that the spiral flow in the arterial system plays a beneficial role in protecting the arterial wall from atherogenesis. Meanwhile, it supported the concept that the receptor-mediated bindings of LDL uptake, the barrier function of the arterial endothelial linings and the mass transport phenomenon of LDL concentration polarization are all involved in the infiltration/accumulation of atherogenic lipids within the arterial wall.