Age-dependent loss of TM in lungs during endotoxemia. (A) Western blot analysis of a time course experiment assessing TM levels in lungs of young (4 months) and aged (24 months) mice that were sacrificed 6 and 12 hours after LPS injection (2.5 mg/kg, intraperitoneal). The control mice without LPS injection are represented by 0 h. Each lane contained 40 μg of protein derived equally from 5 individual mice. The membrane was reprobed with anti–β-actin antibody to assure equal protein loading. (B) Densitometric analysis of panel A. (C) TM levels at 12 hours after LPS injection were further compared among individual samples, which were pooled in panel A. Each lane contained 40 μg of protein from an individual mouse. (D) Densitometric analysis of panel C. (E) TM levels in lungs were compared in young mice with a high dose of LPS (20 mg/kg) versus aged mice with a low dose of LPS (2.5 mg/kg) 12 hours after injection (n = 4 in each group). (F) Densitometric analysis of panel E. (D-F) Data are mean ± SD. *Statistical significance (P < .05). **Statistical significance (P < .01).