Alterations in hepatic gluconeogenesis, prostanoid, and intracellular calcium during sepsis

Objective: The metabolic alterations observed during sepsis maybe associated with changes in local concentrations of intracellular calcium (Ca2+) and prostanoid synthesis in the liver. The authors studied hepatocyte intracellular Ca2+ and the release of glucose. and prostanoid in an in-vivo murine liver perfusion model. Methods: Sepsis was induced in anesthetized, fasted rats by cecal ligation and puncture. (CLP, n = 42). Hepatic glucose release was studied in control (n = 10) and CLP (n = 10) groups using a nonrecirculating liver perfusion model with and without lactate as gluconeogenic substrate. Hepatocyte intracellular Ca2+ (n = 11) was measured using the selective indicator Fura-a under basal and epinephrine (10(-5) M) stimulated conditions. 6-Keto-prostaglandin F-1 alpha (6-Keto) and thromboxane B-2 (TxB(2)) were determined from liver perfusate by radioimmunassay (n = 11). Data were analyzed using t-tests and repeated-measures ANOVA. Results: Plasma glucose was significantly lower in CLP groups compared with controls:(74.9 +/- 6.6 vs 115.7 +/- 4.6 mg/dL, p < 0.05). Plasma lactate was:significantly higher in CLP vs controls (3.7 +/- 0.4 vs 1.4 +/- 0.1 mM, p < 0.05). Glucose release in isolated pei fused livers was significantly lower in CLP vs controls (8.5 vs 16 +/- 1.2 mu M/g/hr, p < 0.001). With the addition of lactate + pyruvate to the perfusate, glucose output in CLP livers was significantly lower following 5 (9.9 +/- 0.7 vs 17.7 +/- 1.1 mu M/g/hr, p < 0.05) and 10 (11.9 +/- 1.2 vs 20.6 +/- 1.3 mu M/g/hr, p < 0.001) minutes of perfusion. The basal level of intracellular calcium ([Ca2+](i)) in CLP rats (460.1 +/- 91.6 nM) was significantly higher than in control rats (196.3 +/- 35.5 nM) (p < 0.05). A significant increase(p < 0.05) in [Ca2+](i) occurred after the addition of epinephrine in hepatocytes in control (196.3 +/- 35.5 vs 331.8 +/- 41.4 nM) but not CLP (460.1 + 91.6 vs 489.4 +/- 105 nM) rats. 6-Keto was significantly lower in CLP compared with controls at 30 minutes (25.7 +/- 3.9 vs 33.4 +/- 5.5 pg/mL, p < 0.05), whereas TxB(2) was not significantly altered (52.1 +/- 34.7 vs 87.5 +/- 43.2 pg/mL). Conclusion: These results demonstrate that CLP sepsis is associated with an increase in hepatocyte intracellular free Ca2+ concentration along with attenuation of hormone-mediated Ca2+ mobilization and hepatic gluconeogenesis. Key words: rat; cecal ligation and. puncture; hepatic glucose release; hepatocyte intracellular calcium; 6-keto prostaglandin F-1 alpha; thromboxane B-2; plasma glucose; plasma lactate; Liver perfusion.