Muscarinic receptor reserve and beta-adrenergic sensitivity in tracheal smooth muscle.

Journal of Applied Physiology
S J GunstN A Flavahan

Abstract

The possibility that differences in beta-adrenergic sensitivity among canine trachealis muscles contracted with different contractile agonists are related to differences in the receptor-occupancy characteristics of the contractile agonists was investigated. Relaxation to isoproterenol was compared in muscles contracted with the muscarinic agonists McN-A-343 and acetylcholine (ACh). The apparent dissociation constant (pKB) values for the M1-antagonist, pirenzepine, against ACh (6.96 +/- 0.18) and McN-A-343 (6.84 +/- 0.08) were similar. The pKB values for the M3-antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP) against ACh (8.76 +/- 0.13) and McN-A-343 (8.71 +/- 0.10) were also similar, suggesting that these agonists were activating the same subtype of muscarinic receptor, probably M3. However, the contractile response to ACh was associated with a greater receptor reserve than that for McN-A-343. Isoproterenol relaxed muscles contracted with McN-A-343 much more effectively than those contracted with an equieffective concentration of ACh. The results suggest that the relative resistance of ACh-induced contractions to relaxation by isoproterenol may not be an inherent quality of muscarinic receptor stimulation. Th...Continue Reading

Citations

Feb 1, 1993·The American Review of Respiratory Disease·R W MitchellA R Leff
Aug 16, 2001·American Journal of Physiology. Lung Cellular and Molecular Physiology·H YoshimuraD O Warner
Sep 25, 2007·American Journal of Physiology. Lung Cellular and Molecular Physiology·Reinoud GosensAndrew J Halayko
Oct 12, 2013·Biological Trace Element Research·Zhenying ZhaoGuo'an Luo
Jun 1, 1995·British Journal of Pharmacology·A F RoffelJ Zaagsma
Aug 4, 2009·American Journal of Physiology. Lung Cellular and Molecular Physiology·Isabelle LabontéJames G Martin
Apr 1, 1994·Pharmacology & Therapeutics·E R ChilversR A Challiss
Jul 23, 2021·American Journal of Respiratory Cell and Molecular Biology·Pawan SharmaDeepak A Deshpande

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