Fig. 1

ANP attenuates BLM-induced pulmonary fibrosis in mice. BLM was administered intratracheally to C57BL/6 mice on Day 0, and samples were removed on Day 21. ANP or vehicle was subcutaneously infused using an osmotic mini-pump throughout the experiment. Representative micrographs of lung tissue stained with hematoxylin–eosin (HE: upper panels) and Masson trichrome (MT: lower panels): normal control mice (a, d), BLM-treated mice receiving vehicle (b, e), and BLM-treated mice receiving ANP (c, f). Scale bar: 500 μm. g Fibrotic area, measured using image analysis software, and is expressed as a percentage of the whole lung field. Values represent means ± SEMs (n = 5 mice per group). *p < 0.05. NA: not assessed because of the absence of fibrotic area in normal lungs. h Body weight changes of mice after BLM administration. Values represent means ± SEMs (in normal control group, n = 13; in BLM with vehicle group, n = 15, in BLM with ANP group, n = 14)