An In Vitro Study of Transendothelial Albumin Transport in a Steady State Pipe Flow at High Shear Rates

The effect of high wall shear rates on the uptake of ¹³¹I-albumin by the arterial wall has been studied in vitro using common carotid arteries excised from anesthetized dogs and perfused with a steady state flow of homologous serum. Wall uptake was found to depend nearly linearly upon wall shear rate. The overall transport of ¹³¹I-albumin from the perfusing fluid to the vessel wall appears to be rate controlled by a shear dependent fluid-wall interface process. This study was carried out at high shear rates for flows which were transitional and turbulent. Because of the complexity of such flows, direct measurements of pressure drop were used to determine the shear rate at the vessel wall. Simultaneous pressure drop and flow measurements allowed the determination of the friction factor as a function of Reynolds number; results obtained at the higher Reynolds numbers correspond to those for a rigid pipe with a relative roughness of 0.05.