Alterations in hepatic gluconeogenesis, prostanoid, and intracellular calcium during sepsis.
OBJECTIVE
The metabolic alterations observed during sepsis may be 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 non-recirculating liver perfusion model with and without lactate as gluconeogenic substrate. Hepatocyte intracellular Ca2+ (n = 11) was measured using the selective indicator Fura-2 under basal and epinephrine (10(-5) M) stimulated conditions. 6-Keto-prostaglandin F1alpha (6-Keto) and thromboxane B2 (TxB2) 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 perfused livers was significantly lower in CLP vs controls (8.5 vs 16+/-1.2 microM/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 microM/g/hr, p < 0.05) and 10 (11.9+/-1.2 vs 20.6+/-1.3 microM/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 TxB2 was not significantly altered (52.1+/-34.7 vs 87.5+/-43.2 pg/mL).


CONCLUSIONS
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.
Maitra
S R
SR
Department of Emergency Medicine, University Medical, Center State University of New York Stony Brook 11794-7400, USA. maitra@surg.som.sunysb.edu
Homan
C S
CS
Beuhler
M C
MC
Thode
H C
HC
Henry
M
M
D015121:6-Ketoprostaglandin F1 alpha / Q000096:biosynthesis; D000704:Analysis of Variance; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D005943:Gluconeogenesis; D007773:Lactates / Q000097:blood; D008026:Ligation; D008099:Liver / Q000378:metabolism*; D008297:Male; D011453:Prostaglandins / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000378:metabolism*; D013929:Thromboxane B2 / Q000096:biosynthesis
D001786:Blood Glucose; D007773:Lactates; D011453:Prostaglandins; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D002118:Calcium