Loop diuretics affect skeletal myoblast differentiation and exercise-induced muscle hypertrophy

Abstract

Muscle wasting or sarcopenia contributes to morbidity and mortality in patients with cancer, renal failure, or heart failure, and in elderly individuals. Na+-K+-2Cl− cotransporter 1 (NKCC1) is highly expressed in mammalian skeletal muscle, where it contributes to the generation of membrane ion currents and potential. However, the physiologic function of NKCC1 in myogenesis is unclear. We investigated this issue using the NKCC1 inhibitors bumetanide and furosemide, which are commonly used loop diuretics. NKCC1 protein levels increased during C2C12 murine skeletal myoblast differentiation, similarly to those of the myogenic markers myogenin and myosin heavy chain (MHC). NKCC1 inhibitors markedly suppressed myoblast fusion into myotubes and the expression of myogenin and MHC. Furthermore, phosphorylated and total NKCC1 levels were elevated in mouse skeletal muscles after 6 weeks’ voluntary wheel running. Immunofluorescence analyses of myofiber cross-sections revealed more large myofibers after exercise, but this was impaired by daily intraperitoneal bumetanide injections (0.2 or 10 mg/kg/day). NKCC1 plays an essential role in myogenesis and exercise-induced skeletal muscle hypertrophy, and sarcopenia in patients with renal or heart failure may be attributable to treatment with loop diuretics.

Effect of loop diuretics on skeletal muscle depletion in patients with liver cirrhosis

“…Another member of NKCC family, NKCC2, is a major target of loop diuretics in the kidney. The results of these study could suggest that loop diuretics are involved in the loss of skeletal muscle mass and development of sarcopenia . Therefore, sarcopenia in patients with liver cirrhosis might be attributable to treatment with loop diuretics, and the findings of these basic studies, together with the results of our clinical study, could support this hypothesis.…”

WNK1 regulates skeletal muscle cell hypertrophy by modulating the nuclear localization and transcriptional activity of FOXO4

“…2D ). The calculated fusion index 8 , which represents the percentage of multinucleated MHC-positive myotubes, was also lower in the WNK1-silenced group, suggesting that the myogenic fusion of myoblasts into myotubes was impaired by WNK1 silencing (Fig. 2E ).…”

“…To determine whether WNK1 modulates muscle cell hypertrophy or myogenic differentiation, we measured myotube diameter and the myoblast fusion index 8 after small interfering RNA (siRNA)-mediated silencing of WNK1, SPAK, or OSR1 (Fig. 2A ) using immunofluorescence for MHC in differentiated C2C12 myotubes 4 days after switching the culture medium to DM.…”

“…We previously demonstrated that Na + -K + -2Cl − co-transporter 1 (NKCC1), a member of the SLC12A family cation-coupled chloride transporter family, is an important regulator of mammalian skeletal myogenesis, and loop diuretics, which inhibit the transporter, may clinically underlie the pathogenesis of sarcopenia 8 . The other SLC12A family members NKCC2 and Na + -Cl − co-transporter (NCC), which are mutated in the salt-losing nephropathies Bartter syndrome and Gitelman syndrome respectively, are known to physiologically govern salt reabsorption and blood pressure in the kidneys and arteries 9 , 10 .…”

Loop diuretics are associated with greater risk of sarcopenia in patients with non-dialysis-dependent chronic kidney disease

“…Mandai et al have reported that loop diuretics suppressed skeletal muscle differentiation by blocking Na + -K + -2Cl - cotransporter 1 (NKCC1), which was highly expressed in skeletal muscle by using murine skeletal muscle cells in vitro and in vivo . Thus, NKCC1 was presumed to play an essential role in myogenesis [ 22 ], and it is possible that use of loop diuretics in patients with CKD may elevate the risk of sarcopenia. To date, our study is the first to our knowledge to demonstrate the effect of loop diuretics on risk of developing sarcopenia in a population-based sample.…”