Inhibition of anaphylatoxin C3a‐ and C5a‐ but not nerve stimulation‐ or Noradrenaline‐dependent increase in glucose output and reduction of flow in Kupffer cell‐depleted perfused rat livers

In isolated in situ perfused rat livers, infusion of anaphylatoxins C3a and C5a, activation peptides of the complement system, as well as stimulation of sympathetic hepatic nerves have been shown to increase hepatic glucose output and to reduce hepatic flow. These effects were mediated via an at least partially prostanoid‐dependent intercellular signalling chain between nonparenchymal cells and hepatocytes. Kupffer cells have been implicated as the source of prostanoids in the anaphylatoxin‐dependent signalling chain and Ito cells in the nerve stimulation‐dependent signalling chain, because anaphylatoxins and noradrenaline increased prostanoid synthesis in isolated Kupffer and Ito cells, respectively. To further corroborate this hypothesis, anaphylatoxins were infused and hepatic nerves were stimulated in perfused rat livers in which Kupffer cells had been largely depleted by treatment of the animals with gadolinium chloride. Native human anaphylatoxin C3a (nhC3a) and recombinant rat anaphylatoxin C5a (rrC5a) increased prostanoid formation as well as glucose output and reduced flow in perfused rat liver. In Kupffer cell‐depleted rat livers, the nhC3a‐ and rrC5a‐mediated prostanoid formation was nearly abolished, and the increase in glucose output and the reduction of flow were reduced to between 30% and 50% (area under the curve [AUC]) of control livers. In contrast, stimulation of hepatic nerves increased glucose output and reduced flow to a similar extent in Kupffer cell‐depleted livers as in control livers. These results indicate that Kupffer cells were not involved in the prostanoid‐mediated nerve stimulation‐dependent increase in glucose output and reduction of flow. Kupffer cells seemed, however, to be at least one major source of the anaphylatoxin‐mediated prostanoid formation and, consequently, stimulation of glucose release and flow reduction in perfused liver. Because the metabolic and hemodynamic anaphylatoxin effects were not completely blocked in livers of gadolinium‐treated animals, either Kupffer cells may not have been entirely eliminated, or yet another nonparenchymal cell type and mediator might be involved in the anaphylatoxin‐elicited intercellular communication between nonparenchymal cells and hepatocytes.