Figure 5.

β₂-adrenergic receptor activation is required for (R)-albuterol–mediated increase in iNOS expression. NHBE cells were stimulated with 10 ng/ml of IL-1β + IFN-γ with or without 10⁻⁵ M (R)-albuterol for 18 h in the presence or absence of the β₂-adrenergic antagonist, ICI 118551. iNOS message, normalized to β-actin message, was assayed by TaqMan real-time RT-PCR. β₂-adrenergic receptor antagonism alone did not affect IL-1β + IFN-γ–induced iNOS transcription, but (R)-albuterol augmentation of iNOS message was blocked by ICI 118551. NHBE cells incubated in medium alone exhibited no measurable iNOS message. Dashed line represents IL-1β + IFN-γ–induced iNOS expression. Data are presented as mean ± SEM (n = 4). ^* Significantly greater than cytokine-induced iNOS expression (P < 0.01); ^† significantly lower than iNOS message expression after cytokine + (R)-albuterol treatment (P < 0.01). N.S., no significant difference (P > 0.05).