Transport in rat vessel walls. I. Hydraulic conductivities of the aorta, pulmonary artery, and inferior vena cava with intact and denuded endothelia

Abstract

Shou, Yixin, Kung-ming Jan, and David S. Rumschitzki. Transport in rat vessel walls. I. Hydraulic conductivities of the aorta, pulmonary artery, and inferior vena cava with intact and denuded endothelia. Am J Physiol Heart Circ Physiol 291: H2758 -H2771, 2006. First published May 26, 2006 doi:10.1152/ajpheart.00610.2005In this study, filtration flows through the walls of the rat aorta, pulmonary artery (PA), and inferior vena cava (IVC), vessels with very different susceptibilities to atherosclerosis, were measured as a function of transmural pressure (⌬P), with intact and denuded endothelium on the same vessel. Aortic hydraulic conductivity (L p) is high at 60 mmHg, drops ϳ40% by 100 mmHg, and is pressure independent to 140 mmHg. The trends are similar in the PA and IVC, dropping 42% from 10 to 40 mmHg and flat to 100 mmHg (PA) and dropping 33% from 10 to 20 mmHg and essentially flat to 60 mmHg (IVC). Removal of the endothelium renders L p(⌬P) flat: it increases Lp of the aorta by ϳ75%, doubles L p of the PA, and quadruples Lp of the IVC. Specific resistance (1/L p) of the aortic endothelium is ϳ47% of total resistance; i.e., the endothelium accounts for ϳ47% of the ⌬P drop at 100 mmHg. The PA value is 55% at Ͼ40 mmHg, and the IVC value is 23% at 10 mmHg. L p of the intact aorta, PA, and IVC are order 10 Ϫ8 , 10 Ϫ7 , and 5 ϫ 10 Ϫ7 cm⅐s Ϫ1 ⅐mmHg Ϫ1, and wall thicknesses are 145.8 m (SD 9.3), 78.9 m (SD 3.3), and 66.1 m (SD 4.1), respectively. These data are consistent with the different wall structures of the three vessels. The rat aortic L p data are quantitatively consistent with rabbit Lp(⌬P) (Tedgui A and Lever MJ.

A theory for water and macromolecular transport in the pulmonary artery wall with a detailed comparison to the aorta

“…Tompkins simplified geometric model yielded a factor of 3: that the PA media diffusivity far exceeds that of the aorta is consistent with a variety of evidence that the PA is far sparser and more permeable to both water and macromolecules than the aorta: the PA has a far higher L pt * than the aorta (45). The in vitro experiments of Lever and Jay (34) showed that the PA wall has a greater distribution volume albumin than systemic arteries.…”

“…Given their different ⌬P*, it is not a priori obvious which experiences the higher fluid flux. Shou et al (45) found this flux, wall L p * ϫ ⌬P*, was the same in the aorta, PA and even the inferior vena cava, to within experimental error. Shou et al (46) found the rat PA endothelium also leaks HRP focally, not uniformly, over a 4-min circulation and PA and aorta focal HRP spot growth with HRP circulation time are both rapid and surprisingly similar to each other and to the aorta study of Chuang et al (9).…”

“…This indicates that the flow resistance due to the endothelium plus SI, including effects of SI compression and IEL fenestral blockage (22,24), contribute a smaller fraction of the total wall resistance in the PA than the aorta. [The statement of Shou et al (45) * are remarkably similar near the cleft, despite the vessels' very different ⌬P* and total wall L pt * . The local SI radial Peclet number, Pe SI ϭ f 1 r*U 1 * /␥ 1 D 1 * , the ratio of the SI radial advection to molecular diffusion, is a way to represent the radial flow rate nondimensionally.…”

“…1 Since electron micrographs (45,46) show the PA and aorta have the same basic structural layers: endothelium, SI, IEL, media, and adventitia, Fig. 1, A and B, applies to both vessels the same basic 2-D convection-diffusion model (similar, but not identical, to that in Refs.…”

“…In RESULTS AND DISCUSSION, these changes showed that the impact of the aorta's leaky EC junction extends into the media, causing nonuniformities in the pressure, velocity, and macromolecular concentration near the IEL. The PA wall's similar layered ultrastructure (45) and looser media suggest, and Figs. 3 and 5 find, even more significant pressure and concentration nonuniformities in the PA than in the aorta.…”