Effect of pressure on transmural fluid flow in different de-endothelialised arteries

Abstract

The effect of pressure on filtration across different de-endothelialised arteries has been studied experimentally and the existing theoretical model is validated. Segments of different arteries are excised, de-endotheliaslised and cannulated. Bovine serum albumin Krebs solution is used as perfusate. Transmural water flux is measured by following the movement of an air bubble in a calibrated capillary, which connects the artery to a pressure reservoir; the pressure of which is varied. The hydraulic conductivity L_p is calculated from the flux values. Using available experimental parameters in the case of the thoracic and abdominal aorta, a theoretical model is validated using the experimental results. As the elastic constant for the carotid artery is not available, the theoretical model is used to calculate the elastic constant at different transmural pressures. The values calculated are in the range −4·9×10⁻⁸ to −5·7×10⁻⁹ cm² dyne⁻¹ between 50 and 135 mm Hg. Both theoretical and experimental results show a decrease in L_p values with an increase in transmural pressure for the thoracic and abdominal aorta, whereas a different trend is observed in the case of the carotid artery. The L_p values increase at 90 mm Hg, as compared with 50 mm Hg, and with a further increase in transmural pressure the values decrease.