Affiliation:
1. Servizio di Fisiopatologia Respiratoria, Dipartimento di Medicina Interna e Specialità Mediche, Università di Genova, 16132 Genova, Italy
Abstract
The effects of pharmacological stimulation at different levels of the β-adrenoceptor (AR) pathway, including the receptor, the receptor-coupled Gs protein, and adenylyl cyclase, were studied by simultaneous measurements of acetylcholine (ACh) release and isometric force evoked by electric stimulation in isolated bovine trachealis. The β-AR agonists isoproterenol (10-6 and 10-5 M) and salbutamol (10-7 to 10-5 M) significantly attenuated both ACh release and contractile force. Forskolin, at 10-6 M, significantly increased ACh release without effect on contractile force, whereas at 10-5 M it increased ACh release but significantly decreased force. Activation of Gs protein by cholera toxin (10 μg/ml) significantly attenuated both ACh release and contractile force, but its effect on ACh release was abolished by calcium-activated potassium (KCa)-channel blocker iberiotoxin (10-7 M). The KCa-channel opener NS-1619 (10-4 M) attenuated significantly both ACh release and contractile force. It is concluded that β-AR agonists attenuate cholinergic neurotransmission in isolated bovine trachealis model by a mechanism not involving cAMP but KCa channels.
Publisher
American Physiological Society
Subject
Physiology (medical),Physiology
Cited by
20 articles.
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