p38 signaling pathwayinvolved in the expression of HMGB1 in a rat model of ventilator-indnced lung injury

：Objective To investigatethe role of p38 MAPK pathway in the expression of high mobility group box 1 (HMGB1) inlung tissue in a rat model of ventilator-induced lung injury. Method Twenty-fonr healthySprague Dawley (SD) rats were randomly divided into 3 groups (n = 8 each) : group A,spontaneous breathing; group B, small tidal volume ventilation (Vt = 8 mL/kg) and group C,high tidal volume ventilation (Vt = 40 mL/kg). 1he animals in group B and C weremechanically ventilated for 4 hours and all animals were sacri-riced. The lungs wereremoved for: (1) lung lavage and determination of total protein contnt and WBC andneu-trophil counts in broncho-alveolar lavage fluid (BALF) ; (2) determination of W/D lungweight ratio and myelop-erexidnse (MPO) activity; (3) detennination of HMGB1 protein andmRNA expression and p38 MAPK activity in lung tissue. Differences within the groups wereanalyzed using One way ANOVA. Results The inflammatory re-sponse as evidenced by totalprotein (1.77 ± 0.68) g/L and WBC (106.55 ± 28.17) × 10~7/L in BALF, W/D lung weightratio (7.16±1.02) and MPO activity (3.94±1.21) U/g were significantly higher in group Ccom-pared with group A (P 0.05). Conclusions High tidal volume ventilation in-daces acute lunginjury, which may be related with upregulation of HMGB1 expression through p38 MAPK signalpathway.