Fuster C, Idoux R, Berthier C, Jacquemond V, Allard B. Mammalian skeletal muscle does not express functional voltage-gated H
+ channels.
Am J Physiol Cell Physiol 2018;
315:C776-C779. [PMID:
30281323 DOI:
10.1152/ajpcell.00357.2018]
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Abstract
High metabolic activity and existence of a large transmembrane inward electrochemical gradient for H+ at rest promote intracellular acidification of skeletal muscle. Exchangers and cotransports efficiently contend against accumulation of intracellular H+ and associated deleterious effects on muscle functions. Voltage-gated H+ channels have also been found to represent another H+ extrusion pathway in cultured muscle cells. Up to now, the skeletal muscle cell was therefore the unique vertebrate excitable cell in which voltage-gated H+ currents have been described. In this study, we show that, unlike cultured cells, single mouse muscle fibers do not generate H+ currents in response to depolarization. In contrast, expression of human voltage-gated H+ channels in mouse muscle gives rise to robust outward voltage-gated H+ currents. This result excludes that inappropriate experimental conditions may have failed to reveal voltage-gated H+ currents in control muscle. This work therefore demonstrates that fully differentiated mammalian muscle fibers do not express functional voltage-gated H+ channels and consequently can no longer be considered as the only vertebrate excitable cells exhibiting voltage-gated H+ currents.
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