Fig. 3. Modulation of lipopolysaccharide-stimulated cytokine response in cultured whole blood assays by norepinephrine. Dose–response characteristics of norepinephrine and contribution of adrenergic receptors were studied by adding increasing concentrations of norepinephrine (0, 10, 100, 1,000 ng/ml) in the absence or presence of the α1- and β-adrenergic receptor blocking agent labetalol (10 −5m) to diluted whole blood from healthy volunteers. For details see Materials and Methods. Norepinephrine decreased tumor necrosis factor α (TNF-α;A ) while simultaneously increasing interleukin (IL)-10 response (B ) to lipopolysaccharide stimulation. Both effects were receptor-mediated as reflected by the attenuation in the presence of labetalol. Data are mean ± SD for five individual experiments for each condition.