ISSN:
1573-4919
Keywords:
cardiomyocytes
;
desensitization
;
G proteins
;
adenylyl cyclase
;
cross-talk
;
adrenergic receptor
;
adenosine receptor
;
muscarinic receptor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Chronic exposure of cells to cognate agonists has been established to cause homologous desensitization of G protein-coupled receptors. In this work, we show that exposure of adult rat eardiomyoeytes to isoproterenol (ISO) for 24 h led to the desensitization of β-adrenoceptor (β-AR) coupled adenylyl cyclase (AC) activity, which was associated with an increased inhibition of AC by M2-muscarinic receptor (MR) agonist, carbachol (Cch), and a decreased inhibition of AC by A1-adenosine receptor (AdR) agonist, N6-phenylisopropyladenosine (R-PIA). Chronic exposure of eells to Cch caused the desensitization of M2-MR-coupled AC, decreased the inhibitory action of R-PIA on AC and increased ISO-stimulated AC, while chronic exposure to R-PIA caused the desensitization of A1-AdR-coupled AC and modestly increased ISO-stimulated AC without any significant effect on Cch inhibition of the enzyme. Thus, chronic exposure ol cardiomyocytes revealed for the first time a more complex and differential nature of cross-talk among the three major G-coupled receptors in modulating AC.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006874928424
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