JPET xPharm- The Comprehensive Pharmacology Reference

Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Full Text (PDF)
Right arrow Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Janssen, L. J.
Right arrow Articles by Daniel, E. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Janssen, L. J.
Right arrow Articles by Daniel, E. E.

Classification of postjunctional beta adrenoceptors mediating relaxation of canine bronchi

LJ Janssen and EE Daniel

Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.

Adrenoceptors mediating relaxant responses to exogenously added or endogenously released catecholamines in isolated canine bronchi (3rd- 6th order) were characterized using selective beta receptor agonists and antagonists. Norepinephrine (3 x 10(7) to 3 x 10(-5) M) or isoproterenol (3 x 10(-8) to 10(-6) M) fully relaxed tissues precontracted with 3 x 10(-7) M carbachol (Cch). Salbutamol (Sal) also relaxed Cch-precontracted tissues, but this relaxant effect was extremely sensitive to the concentration of precontracting agent used: the maximal effect of Sal was 100, 79 and 28% reversal of tone in tissues precontracted with 2 x 10(-8), 10(-7) and 3 x 10(-7) M Cch. The effects of isoproterenol were antagonized by propranolol. Norepinephrine relaxations were antagonized by the beta-1-selective antagonist ICI 89,406 (pA2 = 7.70) and the beta-2-selective antagonist ICI 118,551 (pA2 = 6.33). Sal-relaxations were antagonized by ICI 118,551 (pA2 = 8.91). Field stimulation in tissues precontracted with McNeil A343 (M1-selective muscarinic agonist) produced transient relaxations which were antagonized by ICI 89,406 but not ICI 118,551 (both 10(-9) to 10(-7) M). Thus, exogenous and endogenous catecholamines relax canine bronchial smooth muscle by activating both beta-1 and beta-2 adrenoceptors, although the latter seen to play a significant role only when low concentrations of Cch were used.

Volume 256, Issue 2, pp. 670-676, 02/01/1991
Copyright © 1991 by American Society for Pharmacology and Experimental Therapeutics




This article has been cited by other articles:


Home page
 Am. J. Physiol. Lung Cell. Mol. Physiol.Home page
L. J. Janssen
Ionic mechanisms and Ca2+ regulation in airway smooth muscle contraction: do the data contradict dogma?
Am J Physiol Lung Cell Mol Physiol, June 1, 2002; 282(6): L1161 - L1178.
[Abstract] [Full Text] [PDF]

Home page
 J. Pharmacol. Exp. Ther.Home page
A. M. Johri and L. J. Janssen
N-Type Ca2+ Channels Trigger Release of Excitatory and Inhibitory Neurotransmitter from Nerve Endings in Canine Bronchi
J. Pharmacol. Exp. Ther., August 1, 1999; 290(2): 847 - 853.
[Abstract] [Full Text]


Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
All ASPET Journals Molecular Pharmacology Pharmacological Reviews
Molecular Interventions Drug Metabolism and Disposition

Copyright © 1991 by the American Society for Pharmacology and Experimental Therapeutics.