Regulation of oxygen consumption and microcirculation by alpha-sympathetic nerves in isolated perfused rat liver

In isolated rat liver perfused at constant flow with erythrocyte-free Krebs-Henseleit bicarbonate buffer containing 5 mM glucose and 2 mM lactate, perivascular stimulation of the hepatic nerves caused a rapid decrease of oxygen uptake, a decrease of the periportal and, after a transient rise, of the perivenous tissue po2 of surface acini, an increase of portal pressure, and an enhancement of glucose output. Furthermore, nerve stimulation changed the intrahepatic distribution of the perfusate drastically. Infusion of trypan blue 20 s after nerve stimulation resulted in a heterogeneous staining of the liver both at the surface and in cross-sections, while it led to a homogeneous distribution in non-stimulated controls. It is concluded that the major component in the mechanism of the nerve-dependent decrease of oxygen uptake is the microcirculatory change rather than a metabolic effect.