Expression of biological markers. Real-time polymerase chain reaction analysis of biological markers associated with inflammation (interleukin β (IL-β) and IL-6), apoptosis (procaspase 3), fibrogenesis (pro-collagen type III, PCIII) and damage inflicted upon the endothelium (intercellular adhesion molecule 1 (ICAM-1)) and alveolar type I epithelial cells (receptor for advanced glycation end product, RAGE). Relative gene expression was calculated as a ratio of the average gene expression levels compared with the reference gene (36B4) and expressed as fold change relative to NV (nonventilated). ALIexp: extrapulmonary acute lung injury; ALIp: pulmonary acute lung injury; BIVENT: biphasic positive airway pressure at different rates of time-cycled controlled breaths: 100, 75 and 50 breaths/min; NV: nonventilated; P2 = type II epithelial cell; PCV: pressure-controlled ventilation. Boxplots show medians and IQRs of five rats in each group. *P < 0.05 vs. NV, #P < 0.05 vs. PCV.