Abstract
Weak electromagnetic fields (WEF) enhance Ca2+ entry into cells via voltage-gated Ca2+ channels and affect various aspects of metabolism, structure, and function. However, little information is available on the effect of WEF on skeletal muscle, which depends primarily on intracellular Ca2+ stores for function and metabolism. Here, we examine the effects of 30 min exposure of rat primary myotube cultures to WEF (1.75 μT, 16 Hz) on Ca2+ handling and creatine kinase (CK) release. Free myoplasmic Ca2+ concentration ([Ca2+ i]) was measured with the ratiometric dye indo-1. WEF did not affect basal [Ca2+]i but decreased the twitch [Ca2+]i transient in a time-dependent manner, and the twitch amplitude was decreased to ∼30 % after 30 min. WEF completely abolished the increase in [Ca2+]i induced by potassium chloride (∼60 mM) but had no effect on the increase induced by caffeine (∼6 mM). Hypoxia (2 h exposure to 100 % argon) resulted in a marked loss of CK into the medium (400 % of normoxic value), as well as a rapid (within 20 min) and sustained increase in basal [Ca2+]i (∼20 % above baseline). However, during exposure to WEF, basal [Ca2+]i remained constant during the initial 60 min of hypoxia and, thereafter, increased to levels similar to those observed in the absence of WEF. Finally, WEF blocked about 80 % of hypoxia-mediated CK release (P < 0.05). These data demonstrate that WEF inhibits increases in [Ca2+]i by interfering with muscle excitation and protects against muscle damage induced by hypoxia. Thus, WEF may have therapeutic/protective effects on skeletal muscle.
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This research was supported by a grant from the Gasner Foundation.
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All experiments were conducted according to the guidelines of the National Institute of Health for the care and use of laboratory animals and approved by the institutional review board of Bar Ilan University.
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Adler, D., Fixler, D., Scheinowitz, M. et al. Weak electromagnetic fields alter Ca2+ handling and protect against hypoxia-mediated damage in primary newborn rat myotube cultures. Pflugers Arch - Eur J Physiol 468, 1459–1465 (2016). https://doi.org/10.1007/s00424-016-1837-2
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DOI: https://doi.org/10.1007/s00424-016-1837-2