Investigation of the Hepatic Arterial "Space" under Various Conditions of Flow in the Isolated Perfused Dog Liver

Abstract

A radioactive isotope dilution technique, in which two radioactive tracers were used simultaneously, was employed to investigate the nature of the hepatic arterial vascular bed or arterial vascular "space" in 22 isolated perfused canine livers. The technique continuously monitored the blood leaving the liver for radioactivity so that no assumptions had to be made regarding the representative nature of samples. The concept of an arterial vascular space was defined in terms of the mean circulation time of labeled red cells through the perfused organ, and the variation of this parameter with variations in arterial flow was considered; agreement with other published work was shown. The experiments on the size of the arterial vascular space showed a linear relationship between the arterial fraction of the blood occupying the total hepatic vascular bed and the arterial fraction of the total hepatic blood flow. The evidence from these experiments supported the idea that the artery and the portal vein share a large proportion of the total hepatic vascular bed.ADDITIONAL KEY WORDS isotope dilution arterial vascular "space" mean circulation time hepatic vascular bed portal vein

Control Mechanisms of Intrasinusoidal Flow Pattern of Blood

“…The result is consistent with that reported without stimulation (FIELD and ANDREWS, 1968). A significance of this result, with respect to the intrahepatic pattern of blood flow, is evaluated in following discussion:…”

“…Attempts have been made to demonstrate the existence of the separate sinusoids for blood from only one of two vasculatures of the liver, i.e., the hepatic arterial and portal venous systems. For this purpose, an indicator was infused separately into these two vasculatures to show a difference in patterns of transport of the indicator (a route dependent difference) between the individual vascular beds (BRAUER et al, 1959 ;REES et al, 1964;HOLLENBERG and DOUGHERTY, 1966;FIELD and ANDREWS, 1968 ;COHN and PINKERSON, 1969). The observations obtained from such efforts, however, favor the evaluation that the intrahepatic mixing of arterial and portal blood occurs on entry to the sinusoids and/or within them so that the majority of the sinusoids is perfused by mixed blood (GREENWAY and STARK, 1971).…”

“…An analysis of a relationship between fractional flow through the hepatic artery of total liver flow and fractional blood volume of the hepatic arterial bed of total blood volume in the liver (FIELD and ANDREWS, 1968) allows us to know the existence of such functionally separate sinusoids. The experiments were designed to observe the relationship under a variety of hepatic arterial flow and that under stimulation of the hepatic nerves.…”

Application of the Dispersion Model to Describe Disposition Kinetics of Markers in the Dual Perfused Rat Liver

“…This was not the case for the HA-specific space (Sahin and Rowland, 1998b). Two models (serial and parallel models) have been developed to describe the connection between specific and common spaces (Field and Andrews, 1968;Sahin and Rowland, 1998b). The assumptions of both models are very similar made but they differ structurally.…”

“…Nevertheless, this approach is unphysiological in the sense that it excludes the possible contribution from the hepatic artery (HA). Studies concerned with the interaction of these two inputs suggest that both a common and specific space exists: the majority of the sinusoids are the common channels for both streams, whereas a small fraction (approximately 5-10%; Field and Andrews, 1968;Ahmad et al, 1984;Reichen, 1988;Kassissia et al, 1994;Pang et al, 1994;Sahin and Rowland, 1998b) remains specific to the HA. Although existing clearance data suggest that the difference between the PV and HA might be attributable to the presence of the specific arterial space (Ahmad et al, 1984;Pang et al, 1994;Sahin and Rowland, 2000b), they do not provide any information on the disposition characteristics of this space.…”