Autonomic Nervous System and Gut-derived Endotoxin: Involvement in Activation of Kupffer Cells after In Situ Organ Manipulation

Abstract

Gentle in situ organ manipulation rapidly causes disturbances in the hepatic microcirculation, hypoxia, and activation of Kupffer cells. Because the mechanisms of Kupffer cell activation after organ manipulation remain unclear, the possible role of the autonomic nervous system and gut-derived endotoxin were assessed. To mimic what occurs with major abdominal surgery, livers from female Sprague-Dawley rats (200–230 g) underwent minimal dissection for 12 minutes and were manipulated gently or were left alone for 13 subsequent minutes. Kupffer cells were activated 2 hours after manipulation, reflected by a significant increase in intracellular calcium ([Ca²⁺]_i) from about 90 nM in unmanipulated controls to more than 180 nM in response to lipopolysaccharide (LPS 100 ng/ml). Furthermore, Kupffer cells from manipulated rats produced about threefold more tumor necrosis factor-α after LPS (100 ng/ml) than did the unmanipulated controls. Moreover, O₂ uptake of ex situ perfused liver was increased from about 110 μmol/g/hr in unmanipulated controls to more than 160 μmol/g/hr 2 hours after organ manipulation. Binding of pimonidazole (120 mg/kg IV), a 2-nitroimidazole hypoxia marker given 2 hours after manipulation, increased about 2.5-fold, and hepatic glycogen was depleted. Two hours after organ manipulation gut permeability to horseradish peroxidase was elevated and endotoxin in the portal venous blood was increased twofold. Microsurgical hepatic denervation, ganglionic blockade, adrenalectomy, and antibiotics to sterilize the gut before manipulation prevented activation of Kupffer cells by organ manipulation. Hexamethonium and adrenalectomy prevented increases in gut permeability caused by manipulation. Although antibiotics blunted the increase in portal venous endotoxin significantly, there was no effect on gut permeability. These data indicate for the first time that both the autonomic nervous system and gut-derived endotoxin are involved in activation of Kupffer cells after organ manipulation.