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Male Wistar rats weighing 250～300 g were purchased from the Animal Center of the Chinese Academy of Science, Shanghai, China. The rats were fed rat chow with free access to tap water and housed in temperatureand humidity-controlled animal quarters with a 12-h light/dark cycle. All procedures were approved by the Institutional Animal Care Committee.

Animals were anesthetized with urethane (1250 mg/kg intraperitoneally [IP]). A polyethylene catheter was implanted in the right external jugular vein for the continuous infusion of solutions by using a Razel Model WZ-50C syringe pump. The rats were randomly divided into seven groups (six rats per group): 1) controls, 2) LPS; 3-6) LPS plus HES 3.75, 7.5, 15, or 30 mL/kg; and 6)  HES alone (30 mL/kg). Immediately after the time reading, LPS (6 mg/kg IP; Escherichia coli O55:B5, Sigma Chemical Co., St. Louis, MO) was given over 20 s. HES (HAES-Steril 200/0.5, 6%; Fresenius Kabi) was infused beginning at 1 min at 0.2 mL/min. In the control and HES-alone groups, 0.9% saline vehicle (3 mL/kg IP) was given instead of LPS at Time 0. In the control and LPS groups, saline 30 mL/kg was infused instead of HES. In a pilot study, the blood pressure of rats was measured with a microtip manometer (Millar, Houston, TX) inserted into the femoral artery; no significant hemodynamic instability was encountered during the procedure.

The rats were killed by exsanguination 4 h after the LPS challenge, and lung microvascular permeability was assessed by quantitating the extravasation of Evans blue dye into lung parenchyma. In another set of experiments, animals underwent the same treatments. Heparinized blood samples were obtained by a cardiac puncture with a heparin-coated 18-gauge needle either at 2 h (for neutrophil isolation and electrophoretic mobility shift assay [EMSA]) or 4 h (for flow cytometry analysis) after LPS challenge. The lung tissue was also collected either at 2 h (for EMSA) or 4 h (for determination of lung wet/dry weight ratio, myeloperoxidase [MPO] analysis, and enzyme-linked immunosorbent assay [ELISA]) after LPS challenge, frozenin liquid nitrogen, and stored at －80°C.