Beating Of The Heart: Differentially Regulated In The Upper And Lower Chambers

Main Category: Cardiovascular / Cardiology
Article Date: 17 Aug 2008 - 8:00 PDT

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Rodolphe Fischmeister and colleagues, at INSERM UMR-S 769, France, have provided evidence that the contraction of the two regions of the heart, the atria and the ventricles, is differentially regulated.

The contraction phase of the heart beat is controlled by several pathways, including one initiated by stimulation of cell surface proteins known as beta-adrenergic receptors. At the molecular level, the flow of Ca2+ through protein channels known as L-type Ca2+ channels has a central role in the regulation of the contraction of the heart by beta-adrenergic receptors. Previous data have indicated that stimulation of beta-3-adrenergic receptor (beta-3-AR) decreases the contractility of tissue from human ventricles (the lower chambers of the heart) and decreases the activity of ventricle L-type Ca2+ channels in various animal models. In contrast, Fischmeister and colleagues have now found that beta-3-AR stimulation increases the activity of L-type Ca2+ channels in heart cells isolated from human atria (the upper chambers of the heart) and increases the contractility of human atrial tissue. This demonstration that beta-3-AR stimulation has opposing effects on human atrial and ventricular tissue has important implications for those developing therapeutics targeting beta-adrenergic receptors for the treatment of cardiovascular diseases.

TITLE: Beta-3-adrenergic receptor activation increases human atrial tissue contractility and stimulates the L-type Ca2+ current

AUTHOR:
Rodolphe Fischmeister
INSERM UMR-S 769, Châtenay-Malabry, France.
http://www.inserm.fr

View the PDF of this article here.

Source:
Karen Honey
Journal of Clinical Investigation