Selectivity of beta-adrenergic stimulating and blocking agents.
Studies have been performed to answer two questions: whether there are subgroups of beta 2-receptors separating effects in bronchial and skeletal muscle and whether beta 1-receptors in asthmatic airways mediate bronchoconstriction. Asthmatic patients have been studied in randomised cross-over trials. Effects on FEV1, heart rate and skeletal muscle tremor have been monitored. In some experimental studies, two new compounds, D2343 and QH-25, have shown a selectivity for beta 2-receptors in bronchial muscle compared to skeletal muscle. Studies in asthmatics did not confirm this. Thus, the beta 2-receptors in the two organs appear to be identical. The clinical effect of beta 1-receptors in the the airways was studied by giving selective beta 1-receptor blocking agents. It was shown that pafenolol , a beta-blocker more beta 1-selective than metoprolol, had less effect on FEV1 than metoprolol given in equipotent beta 1-blocking doses. Beta 1-receptor stimulation with a new selective beta 1-stimulating agent, prenalterol, did not give bronchodilation in doses which gave a significant increase of heart rate. Thus, beta 1-receptors do not contribute to bronchodilation in asthmatic patients.
D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000403:Airway Resistance / Q000187:drug effects; D000420:Albuterol / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy*; D001980:Bronchi / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009655:Octopamine / Q000031:analogs & derivatives / Q000627:therapeutic use; D010627:Phenethylamines / Q000627:therapeutic use; D011943:Receptors, Adrenergic, beta / Q000187:drug effects; D013726:Terbutaline / Q000627:therapeutic use
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D010627:Phenethylamines; D011943:Receptors, Adrenergic, beta; D009655:Octopamine; C013742:QH 25; C033651:D 2343; D013726:Terbutaline; D000420:Albuterol