β-Adrenergic receptor function and oxygen radical production in bovine pulmonary alveolar macrophages

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Abstract
Reactive oxygen species production by bovine pulmonary alveolar macrophages was evaluated by a chemiluminescence assay utilizing luminol and opsonized zymosan. Incubation with dobutamine (5 .times. 10-8 and 5 .times. 10-7 M) or isoproterenol (5 .times. 10-8 and 5 .times. 10-7 M) prior to zymosan challenge significantly (p < 0.05) increased the time for chemiluminescence to begin, and significantly decreased the level of maximum chemiluminescence. The agonists'' inhibitory effects on maximum chemiluminescence were significantly reduced by pre-incubation with the appropriate antagonist (atenolol at 1 .times. 10-6 M for dobutamine; and propranolol at 1 .times. 10-6 M for isoproterenol). Salbutamol at 1 .times. 10-6 M significantly reduced the level of maximum chemiluminescence only, but did not increase the time for chemiluminescence to begin. This effect was significantly reduced by the presence of the .beta.2-antagonist ICI 118,551 at 1 .times. 10-6 M. The results reveal the presence of .beta.1- and .beta.2-adrenoceptors on bovine pulmonary alveolar macrophages, and suggest that these receptors are important in the regulation of reactive oxygen species production by these cells.