Alpha-Adrenergic Hyper-Responsiveness in Asthma

Abstract

Because alpha-adrenergic stimulation causes bronchoconstriction, the alpha-adrenergic responsiveness of 21 subjects with allergic asthma was compared with that of 16 subjects with allergic rhinitis and 38 normal control subjects. None of the patients had taken medications for at least 30 days before study. Alpha-adrenergic responsiveness was measured by the capacity of phenylephrine to constrict the cutaneous vascular bed and to dilate the pupillary sphincter muscle. Asthmatic subjects required 4.0±0.6 ng to reduce their cutaneous blood flow by 50 per cent, whereas normal controls required 32.0±7.5 ng (P<0.005) and subjects with allergic rhinitis required 23.7±9.4 ng (P0.5 mm in response to 1.8±0.14 per cent phenylephrine, patients with allergic rhinitis required 2.4±0.16 (P<0.01), and normal controls needed 2.7±0.07 (P<0.00001). Therefore, the patients with allergic asthma had significantly enhanced alpha-adrenergic responses when compared both to normal subjects and patients with allergic rhinitis; the possibility that increased alpha-adrenergic activity contributes to the asthmatic diathesis warrants further exploration. (N Engl J Med 300:642–647, 1979)