There is accumulating evidence of cross-regulation between stimulatory G-protein (Gs)-coupled receptors in human atrium. Chronic β1-adrenoceptor antagonist treatment can sensitize β2-adrenoreceptors, 5-HT4 receptors, histamine H2 receptors and possibly β4-adrenoreceptors. To investigate the mechanism of such cross-talk between Gs-coupled receptors, we have measured the mRNA expression of the cardiac adenylate cyclases (types IV, V, VI and VII) and of β-adrenoceptor kinase 1 in human atria using TaqMan quantitative PCR, and compared expression between patients chronically receiving a β1-adrenoceptor antagonist and non-treated patients. The results showed no difference in gene expression between the two groups of patients; however, significant positive correlations of gene expression between adenylate cyclase subtypes were found. We conclude that β1-adrenoceptor antagonists do not change the absolute levels of gene expression of adenylate cyclase subtypes in human atrium. The co-ordinate regulation among adenylate cyclase subtypes and the influence of β1-adrenoceptor antagonists need to be investigated further.

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