Role of β- adrenoceptor at different stages of bronchial asthma

Objective To investigate the changes of β- adrenergic receptor (βAR) in peripheral lymph ocytes and β (2)AR mRNA levels at different stages of bronchial asthma. Methods β (2)AR density and β (2)AR mRNA level in peripheral lymphocytes, cAMP and cGMP levels in blood plasma were estimated by radioligand binding assay, radioimmunoa ssay and RT- PCR. Results (1) Maximum bound volume (Bmax) and equilibrium dissociation constant (Kd) of β (2)AR of lymphocyte in asthma patients at remission stage were markedly higher t han that in normal subjects, while cAMP levels in blood plasma showed no differe nce. Bmax of β (2)AR and cAMP levels in asthma patients at acute exacerbation s tage were significantly lower than that in normal subjects, and Kds between thes e two groups were not much different. (2) Expression of β (2)ARmRNA in peripher al lymphocytes of asthmatics at remission stage was not significantly different compared with that in normals. Conclusions Amount and function of βAR and β (2)ARmRNA levels are related to asthmatic cond itions. Changes of βAR and β (2)ARmRNA in asthma might rather be a pathologica l change accompanied by the course of the disease than a primary defect.

Role of beta-adrenoceptor at different stages of bronchial asthma.

OBJECTIVE: To investigate the changes of beta-adrenergic receptor (beta AR) in peripheral lymphocytes and beta 2AR mRNA levels at different stages of bronchial asthma. METHODS: beta 2AR density and beta 2AR 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 beta 2AR 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 beta 2AR 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 beta 2ARmRNA in peripheral lymphocytes of asthmatics at remission stage was not significantly different compared with that in normals. CONCLUSIONS: Amount and function of beta AR and beta 2ARmRNA levels are related to asthmatic conditions. Changes of beta AR and beta 2ARmRNA in asthma might rather be a pathological change accompanied by the course of the disease than a primary defect.