2.1 GHz electromagnetic field does not change contractility and intracellular Ca²⁺ transients but decreases β-adrenergic responsiveness through nitric oxide signaling in rat ventricular myocytes

Abstract

Purpose: Due to the increasing use of wireless technology in developing countries, particularly mobile phones, the influence of electromagnetic fields (EMF) on biologic systems has become the subject of an intense debate. Therefore, in this study we investigated the effect of 2.1 GHz EMF on contractility and beta-adrenergic (β-AR) responsiveness of ventricular myocytes.

Materials and methods: Rats were randomized to the following groups: Sham rats (SHAM) and rats exposed to 2.1 GHz EMF for 2 h/day for 10 weeks (EM-10). Sarcomere shortening and Ca²⁺ transients were recorded in isolated myocytes loaded with Fura2-AM and electrically stimulated at 1 Hz, while L-type Ca²⁺ currents (I_CaL) were measured using whole-cell patch clamping at 36 ± 1°C. Cardiac nitric oxide (NO) levels were measured in tissue samples using a colorimetric assay kit.

Results: Fractional shortening and amplitude of the matched Ca²⁺ transients were not changed in EM-10 rats. Although the isoproterenol-induced (10⁻⁶ M) I_CaL response was reduced in rats exposed to EMF, basal I_CaL density in myocytes was similar between the two groups (p < 0.01). Moreover, EMF exposure led to a significant increase in nitric oxide levels in rat heart (p < 0.02).

Conclusions: Long-term exposure to 2.1 GHz EMF decreases β-AR responsiveness of ventricular myocytes through NO signaling.

Keywords::

• EMF
• heart
• ventricular myocyte
• contractility
• calcium
• nitric oxide

Acknowledgements

This study was supported by Akdeniz University Research Coordination Unit with grant number of 2014.02.0122.001.

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.