Constitutive Inhibitory Action of Muscarinic Receptors on Adenylyl Cyclase in Cardiac Membranes and Its Stereospecific Suppression by Hyoscyamine

Title:

Constitutive Inhibitory Action of Muscarinic Receptors on Adenylyl Cyclase in Cardiac Membranes and Its Stereospecific Suppression by Hyoscyamine

Creator:

Jan Říčný, Gualtieri, F., and Stanislav Tuček

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:d12659bb-2619-4a15-abd8-640eafe02cd0
uuid:d12659bb-2619-4a15-abd8-640eafe02cd0
issn:0862-8408

Subject:

Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, Muscarinic receptors, Adenylyl cyclase, Constitutive activity of receptors, Hyoscyamine, Atropine, Heart, Inverse agonist action, 14, and 612

Type:

article, studie, model:article, and TEXT

Format:

print, bez média, and svazek

Description:

Muscarinic acetylcholine receptors in the heart have been shown to display agonist-independent spontaneous (constitutive) activity which causes changes in the opening of cardiac ion channels and in the activity of G proteins. We investigated whether an inhibition of the constitutive activity of muscarinic receptors induced by the binding of antagonist brings about a change in the synthesis of cyclic AMP in rat cardiac membranes, and whether the action of the antagonist is stereospecific. Atropine and S-(-)-hyoscyamine were indeed found to enhance the forskolin-stimulated synthesis of cyclic AMP in rat cardiac (both atrial and ventricular) membranes by up to 24%. The effect was stereospecific and the potency of R-(+)-hyoscyamine was 30 fold lower than that of the S-(-) enantiomer, confirming that the action of hyoscyamine is receptor-mediated. The effect did not depend on the presence of endogenous acetylcholine in the system used. The results strongly suggest that the adenylyl cyclase in the heart is exposed to continuous mild inhibition by constitutively active muscarinic receptors in the membranes of cardiomyocytes., J. Říčný, F. Gualtieri, S. Tuček., and Obsahuje bibliografii

Language:

English

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Source:

Physiological research | 2002 Volume:51 | Number:2

Harvested from:

CDK

Metadata only:

false