Figure 3

Myocardial mononuclear cell accumulation and pro-inflammatory cytokine production are enhanced in old mice. Adult and old mice were treated with lipopolysaccharide (LPS, 0.5 mg/kg, iv) or normal saline. Mononuclear cells in the myocardium were detected by immunofluorescence staining using a polyclonal antibody against murine CD68 (red), and levels of TNF-α, IL-1β, and IL-6 in the myocardium and plasma were measured by ELISA 6 h after LPS treatment. The myocardium of old mice displayed higher densities of mononuclear cells (arrow) after LPS treatment (A) (size bar = 20 μm). In addition, the levels of TNF-α, IL-1β, and IL-6 were higher in the myocardium (B) and plasma (C) of old mice compared to adult mice. Data are expressed as mean ± standard error. *P <0.05 versus corresponding control (Ctrl); ^#P <0.05 versus adult mice treated with LPS.