Adrenergic Agonist and Antagonist Action in Airways of Patients with Bronchial Asthma

Abstract

In this study, the effect of dopamine as agonist dopaminergic receptor and alpha and beta adrenergic receptor was studied both in vivo. The effect of tolazoline as an antagonist of alpha-2 adrenergic receptor was also studied in patients with bronchial asthma and persons with increased bronchial reactibility. Parameters of the lung function are determined by body plethysmography. Raw and ITGV were registered and SRaw was calculated as well. Aerosolization is done with standard aerosolizing machines -Asema. Results gained in vivo shows that stimulation of alpha adrenergic receptor with dopamine (4 µg and 300 µg) causes significant contraction (p > 0.1) of the smooth bronchial musculature. Whereas, blockage of alpha-2 adrenergic receptor with tolazoline (20 mg by inhalator ways) does not change the bronchimotor tonus significantly (p>0.1) when compared to the stimulation of beta-2 adrenergic receptor with hexoprenaline (2 inh. x 0.2 mg) and blocker of cholinergic receptor -ipratropium (2 inh. x 1 mg). Reaction of the smooth musculature to dopamine suggests that this substance may cause constriction through alpha adrenergic receptors. Reaction may also be intermediated in indirect ways through dopaminergic receptor of the cholinergic transmission, with intracellular inhibition of the creation of cAMP.