REDISTRIBUTION OF PORTAL VENOUS BUT NOT HEPATIC ARTERIAL FLOW IS INDUCED BY HEPATIC NERVE-STIMULATION IN THE PERFUSED-RAT-LIVER

The effects of hepatic nerve stimulation, norepinephrine and 6-hydroxy dopamine (6-OHDA) on hepatic hemodynamics were investigated in rat liv ers perfused in situ via both the portal vein and hepatic artery. Nerv e stimulation caused a significant fall in total liver blood flow and an increase in portal and arterial pressures. Norepinephrine and 6-OHD A in addition to causing a fall in flow caused significant pressure in creases in the bed perfused (arterial or portal). Under basal conditio ns, the inter- and intra-lobar distribution of microspheres (Sn-113- o r Co-57-labelled) introduced via the portal vein or via the hepatic ar tery was homogeneous in all 6 liver lobes. During nerve stimulation, h omogeneity of interlobular, microsphere distribution was maintained. H owever, the intralobar distribution of microspheres introduced via the portal vein displayed a significant redistribution from the periphery to the core of each of the four largest lobes studied (p < 0.05). In contrast, when microspheres were introduced via the hepatic artery, th ere was no universal redistribution of microspheres with only one lobe demonstrating a significant decrease in flow to the periphery (p > 0. 05). Infusion of norepinephrine (10(-8) M) or 6-OHDA (1 mg.kg(-1) body weight) via either the hepatic artery or the portal vein was without effect on the intrahepatic distribution of the microspheres. We conclu de from our results that during hepatic nerve stimulation there is a s ignificant redistribution of portal venous but not hepatic arterial fl ow from the periphery to the cove of the liver lobe. The persistence o f hepatic arterial flow during nerve stimulation may represent a prote ctive mechanism by which the periphery of the liver, especially the bi le ducts, remains perfused during a reduction in total liver blood flo w.