Objective To investigate the changes of β-adrenergic receptor (βAR) in peripheral lymphocytes and β2AR mRNA levels at different stages of bronchial asthma. Methods β2AR density and β2AR mRNA level in peripheral lymphocytes, cAMP and cGMP levels in blood plasma were estimated by radioligand binding assay, radioimmunoassay and RT-PCR.Results (1) Maximum bound volume (Bmax) and equilibrium dissociation constant (Kd) of β2AR of lymphocyte in asthma patients at remission stage were markedly higher than that in normal subjects, while cAMP levels in blood plasma showed no difference. Bmax of β2AR and cAMP levels in asthma patients at acute exacerbation stage were significantly lower than that in normal subjects, and Kds between these two groups were not much different. (2) Expression of β2ARmRNA in peripheral lymphocytes of asthmatics at remission stage was not significantly different compared with that in normals. Conclusions Amount and function of βAR and β2ARmRNA levels are related to asthmatic conditions. Changes of βAR and β2ARmRNA in asthma might rather be a pathological change accompanied by the course of the disease than a primary defect.
