Uptake of low density lipoprotein, albumin, and water by deendothelialized in vitro minipig aorta.

The purpose of this research was to study the effect of pressure on arterial hydration in vitro and the effect of pressure and flow (stirred reagent) on the in vitro transport of 125I-albumin and 125I-LDL into deendothelialized minipig aortas over a 24-hour period. It was found that the arterial hydration (fractional mass of water) was 0.740 +/- 0.0043 SEM for control tissue; after 24 hours this rose to 0.745 +/- 0.0038 for 0 mm Hg, 0.752 +/- 0.0046 for 100 mm Hg, and 0.755 +/- 0.0065 for 200 mm Hg. In the transport studies, the following effects were found. The reagent radioactivity concentration and composition did not change with pressure or stirring over the 24-hour period. For unpressurized tissue, the 24-hour normalized uptake [uptake (M mg cm-2) divided by reagent concentration (co mg cm-3)] of albumin was (4.86 +/- 0.43 cm) X 10(-3) from stirred and (5.46 +/- 0.36 cm) X 10(-3) from nonstirred reagent; that of LDL was (0.31 +/- 0.02 cm) X 10(-3) from stirred and (0.37 +/- 0.02 cm) X 10(-3) from nonstirred reagent. Pressurization (100 mm Hg) of the tissue increased albumin uptake by 52% from stirred and by 125% from nonstirred reagent and the LDL uptake by 52% from stirred and 241% from nonstirred reagent. Pressure increased the intimal surface concentration of albumin and LDL at the nonstirred, but not at stirred, interfaces. The electrophoretic properties of the intimal surface fluid showed only minor differences from those of the bulk reagent. These data demonstrate that pressure causes a slight, but significant, increase in arterial hydration and that radiolabeled albumin and LDL appear to be sieved by the superficial intimal layers of the deendothelialized porcine aorta under the in vitro conditions of this study.