Functional subcellular distribution of β1‐ and β2‐adrenergic receptors in rat ventricular cardiac myocytes. Issue 3 (22nd August 2013)

• Record Type: Journal Article
• Authors: Cros, Caroline; Brette, Fabien
• Is Part Of: Physiological reports. Volume 1:Issue 3(2013:Aug.)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2013-08-22
• Subjects: Physiology -- Periodicals; 571
• DOI: 10.1002/phy2.38
• Languages: English
• ISSNs: 2051-817X

Abstract

<abstract abstract-type="main" id="phy238-abs-0001"> <title>Abstract</title> <p>β‐adrenergic stimulation is a key regulator of cardiac function. The localization of major cardiac adrenergic receptors (β<sub>1</sub> and β<sub>2</sub>) has been investigated using biochemical and biophysical approaches and has led to contradictory results. This study investigates the functional subcellular localization of β<sub>1</sub>‐ and β<sub>2</sub>‐adrenergic receptors in rat ventricular myocytes using a physiological approach. Ventricular myocytes were isolated from the hearts of rat and detubulated using formamide. Physiological cardiac function was measured as Ca<sup>2+</sup> transient using Fura‐2‐AM and cell shortening. Selective activation of β<sub>1</sub>‐ and β<sub>2</sub>‐adrenergic receptors was induced with isoproterenol (0.1 μmol/L) and ICI‐118, 551 (0.1 μmol/L); and with salbutamol (10 μmol/L) and atenolol (1 μmol/L), respectively. β<sub>1</sub>‐ and β<sub>2</sub>‐adrenergic stimulations induced a significant increase in Ca<sup>2+</sup> transient amplitude and cell shortening in intact rat ventricular myocytes (i.e., surface sarcolemma and t‐tubules) and in detubulated cells (depleted from t‐tubules, surface sarcolemma only). Both β<sub>1</sub>‐ and β<sub>2</sub>‐adrenergic receptors stimulation caused a greater effect on Ca<sup>2+</sup> transient and cell shortening in detubulated myocytes than in control myocytes. Quantitative analysis indicates that β<sub>1</sub>‐adrenergic stimulation is ~3 times more effective at surface sarcolemma compared to t‐tubules, whereas β<sub>2</sub>‐ adrenergic stimulation occurs almost exclusively at surface sarcolemma (~100 times more effective). These physiological data demonstrate that in rat ventricular myocytes, β<sub>1</sub>‐adrenergic receptors are functionally present at surface sarcolemma and t‐tubules, while β<sub>2</sub>‐adrenergic receptors stimulation occurs only at surface sarcolemma of cardiac cells.</p> </abstract>