Hemodynamics of the Vascular Tree of the Isolated Rat Liver Preparation

¹ From the U. S. Naval Radiological Defense Laboratory, San Francisco, California

The hemodynamic properties of the hepatic vascular bed of the isolated rat liver preparation have been studied by the use of flow-pressure diagrams in experiments involving as a perfusate either whole blood or cell-free rat plasma under an oxygen partial pressure of 2.5 atm. Either perfusion medium yields a nonlinear flow-pressure diagram of sigmoid shape approaching a straight line through the origin at perfusion pressures slightly above physiological ones. Data are also reported concerning change of liver weight with perfusion pressure of the isolated organ. These, together with previously reported results of radiocolloid uptake studies, are incorporated into a representation of the hepatic vascular bed in terms of a population of parallel vascular channels having critical opening pressures distributed between 7 and 13 cm of plasma. The distribution function is described and its bearing upon liver function in relation to liver blood flow is briefly discussed.