Normal alpha 2-adrenergic responses in platelets from patients with asthma.

recent in vivo studies suggest that alpha-adrenergic responses are exaggerated in asthmatic subjects. We studied alpha 2-adrenergic responses in platelets from 12 healthy subjects and 10 patients with asthma who had taken no medication for at least 9 days prior to study except low-dose (less than 600 micrograms daily) beclomethasone diproprionate. Alpha 2-adrenergic inhibiton of prostaglandin E1-stimulated adenosine 3':5; cyclic monophosphate (cAMP) accumulation was normal in platelets from subjects with asthma. The time course of inhibition, the extent of inhibition, and the dose-response relationship did not differ between the groups. Results from allergic and nonallergic patients did not differ, and alpha 2-adrenergic responses were not correlated with age, sex, peak flow rated, or total eosinophil counts. Platelet alpha 2-adrenergic cAMP responses are normal in subjects with asthma.