Beta-adrenergic responses and airway reactivity in healthy adults

Healthy adults aged 18-90 years were tested for lymphocyte and granulocyte cyclic AMP responses to isoproterenol and prostaglandin E1 (PGE1), beta-adrenergic receptor density and antagonist binding properties, and for airway reactivity to methacholine. Our hypothesis was that reduced beta-adrenergic responses occur with aging and are associated with increased airway reactivity. This hypothesis was not supported by the data. Lymphocyte stimulation ratios (cyclic AMP level with stimulation/baseline cyclic AMP level) at higher concentrations of isoproterenol and PGE1 increased significantly with age. There were no significant age trends for any of the other variables. None of the beta-adrenergic responses or receptor properties correlated with airway reactivity to methacholine. beta-Adrenergic responses in lymphocytes and granulocytes from the same subject were weakly correlated at high concentrations. Prior studies which suggest that reduced beta-adrenergic responses and increased airway reactivity are concomitants of normal aging may differ from the present study in subject selection. In healthy older subjects, there appears to be no reduction in leukocyte beta-adrenergic responses or receptor properties and no change in airway reactivity.