A) Fold changes ofTNF-αandIL6mRNA levels in the lungs of healthy rats after 4 hours of spontaneous breathing (non-ventilated), and on mechanical ventilation with 6 ml/kg (low V
), 20 ml/kg (high V
). Bars represent the median of six rats per group. *p = 0.025 when compared to low VT; **p = 0.033 when compared to spontaneous breathing animals. B and C) Effects of 4 hours of spontaneous breathing in non-ventilated, anesthetized animals and of 4 hours of mechanical ventilation with low VT(B) and high VT (C) on systemic protein levels of TNF-α and IL-6. Bars represent the mean values of 6 rats per group.