Figure 1.

Lipopolysaccharide (LPS) stimulation down-regulates β₂-adrenergic receptor (β₂AR) expression. (a) RAW264 cells were stimulated with LPS. The protein levels of β₂AR and GAPDH (loading control) in the plasma membrane were analysed by Western blotting (left panel). The β₂AR messenger RNA (mRNA) and 18S ribosomal RNA (rRNA; loading control) were analysed by reverse transcription–polymerase chain reaction (RT-PCR; right upper panel). Bar graphs show the relative intensity of the PCR bands from three separate experiments (mean ± SEM) (right lower panel). *P < 0·01 versus 0 hr. (b) RAW264 cells were transfected with the β₂ar construct or vector alone. The protein levels of β₂AR and GAPDH (left panel) and mRNA expressions of β₂AR and 18S rRNA (right upper panel) were analysed as in (a). Bar graphs show the relative intensities of the PCR bands from three separate experiments (mean ± SEM) (right lower panel). *P < 0·01 versus 0 hr. (c) mRNA expressions of β₂AR and 18S rRNA (upper panel) were analysed as in (a). Bar graphs show the relative intensities of the PCR bands from three separate experiments (mean ± SEM) (lower panel). *P < 0·01 versus 0 hr. (d) Cells were cultured with or without LPS for 6 hr and were stimulated with salbutamol (1 × 10⁻⁶ m) for the final 30 min. Then, intracellular cyclic AMP concentrations were analysed. *P < 0·05 versus without LPS. (e) Cell size was measured by flow cytometric analysis of forward light scatter characteristics (FSC).