Hepatic circulation in acute hemorrhage with reference to renal circulation

Studies were made on the hemodynamics in the liver and kidney during hemorrhage and retransfusion, using 20 dogs with or without hepatic periarterial nerve plexus, anaesthetized with sodium pentobarbital. The results were as follows. In 14 dogs in which the hepatic periarterial nerve plexus was left intact (Group A), the averages of the hepatic arterial flow (HAF), portal venous pressure (PVP), portal venous flow (PVF), and flow in the right renal artery (RAF) decreased significantly to 38, 64, 35, and 25%, respectively of the control levels when the abdominal aortic pressure (ABP) fell to 40 mm Hg (36% of the control level) during hemorrhage. At the same time the portal venous resistance (PVR) and the right renal vascular resistance (RVR) increased greatly and the hepatic arterial resistance (HAR) either increased or decreased in different dogs. During retransfusion the ABP and vascular resistance returned to nearly the control levels, the PVF increased beyond the control level. In 6 dogs in which the nerve plexus was resected (Group B), the decreases in the HAF and RAF during hemorrhage were not significantly different from those in Group A. These results may suggest the following. The decrease in the HAF during hemorrhage seems to be mostly a passive change resulting from decrease in the systemic blood pressure. Neurogenic regulation may be a little. Further, the existence of the humoral regulation and autoregulation in the HAF were suggested in some cases. While, the responsibilities to hemorrhage and retransfusion appear to be different among the examined three vessels, i.e. the hepatic artery, portal vein, and renal artery. No definite interrelation was seen between the hepatic and renal circulations.