Filtration through damaged and undamaged rabbit thoracic aorta.

The influence of luminal pressure and endothelial removal on fluid filtration across the arterial wall has been studied in the rabbit thoracic aorta. Segments of aorta were excised in such a way as to prevent shortening and depressurization and were filled with a 4% albumin-Tyrode solution. Experiments were carried out at two controlled pressure levels (70 and 180 mmHg). The hydraulic conductivity (Lp) of the total wall, calculated from the filtration data, was 4.00 +/- 1.31 and 2.44 +/- 0.80 (SD) X 10(-8) cm/(s X mmHg) in intact wall at 70 and 180 mmHg, respectively (P less than 0.01), whereas values for deendothelialized arteries were higher (P less than 0.01), being 5.36 +/- 1.62 and 5.27 +/- 0.84, respectively. The apparent pressure dependence of conductivity of the intact wall may be due to altered strain of the interstitial matrix. Removal of the endothelium can increase the hydration and porosity of the medial interstitium but, assuming that the conductivity of the deendothelialized wall at 70 mmHg is the same as that of the normal media, the calculated conductivity of the endothelium is 15.76 X 10(-8) cm/(s . mmHg).