Influence of static and oscillatory pressure/strain on 131I-albumin uptake by the wall of the isolated pig thoracic aorta.

The uptake of 131I-albumin by the wall of the isolated pig thoracic aorta was investigated in vitro to achieve good control of the experimental conditions. The lumena of the arteries were perfused with a balanced salt solution (Hanks') containing the radioactively labelled albumin. Albumin flux was studied at three static intralumenal pressures, viz 6.7, 13.3 and 20 kPa (50, 100 and 150 mmHg) and uptake (normalised per unit dry tissue weight) was found to be approximately doubled on increasing the pressure from 6.7 to 20 kPa (50 to 150 mmHg). With a mean pressure of 6.7 kPa (50 mmHg) the uptake was studied in the presence of sinusoidal pressure oscillations of amplitude in the range 1.3 to 6.0 kPa (10 to 45 mmHg) at frequencies 1, 5 and 11 Hz. At each frequency the uptake was found to be dependent on the pressure amplitude. The dependence at 5 Hz was significantly stronger than at 1 Hz (P < 0.05) and although not significant there was a suggestion that the uptake was higher at 5 than 11 Hz. There was no significance and no suggestion of a difference at 1 and 11 Hz. The possible influence on uptake of the associated oscillatory wall shear component has been considered. The relevance of these findings to macromolecular transport and to the characteristic localisation of atheroma within the arterial tree is discussed.