Heat stress modulates hepatocyte membrane proteins during endotoxemia

BACKGROUND: Hepatic failure following sepsis is one of the important features of burns. Studies have shown that in septic rats, heat stress (HS) has a protective effect on bile acid transporters in hepatocyte membranes. This study investigates the influence of HS on hepatocyte membrane proteins during endotoxemia using 2D gel electrophoresis. METHODS: Endotoxemia in rats was induced by intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS) (n=24), while control rats (n=24) received saline. Twelve rats from each group were exposed to HS 2h prior to LPS or saline injection by external warming to 42 degrees C for 10 min and 12 rats in each group were exposed to ambient temperature 2h prior to LPS or saline injection. Membrane fractions were extracted 12, 24 and 72 h after LPS or saline treatment. Extracted proteins were separated using 2D gel electrophoresis. The most dominant spots were analyzed by MALDI-TOF-MS. RESULTS: Two-dimensional gel electrophoresis differentially identified expressed proteins in all treatment groups. The majority of the spots developed 24h after injection. Membrane proteins; Wnt 13, ribosomal protein L14, VLCAD, BHMT and HIT-40 were found only in HS-LPS. Protein profiles of the groups returned to normal after 72 h. CONCLUSION: We propose that HS during endotoxemia changes hepatic membrane proteins expression, which are involved in metabolism.