Effect of Fe₃O₄-magnetic nanoparticles on acute exercise enhanced KCNQ₁ expression in mouse cardiac muscle

Abstract

While the potential impact of magnetic nanoparticles (MNPs) has been widely explored in almost all medical fields, including cardiology, one question remains; that is whether MNPs interfere with cardiac physiological processes such as the expression and function of ion channels, especially in vivo. KCNQ₁ channels are richly expressed in cardiac myocytes and are critical to the repolarization of cardiac myocytes. In this study, we evaluated the effects of Fe₃O₄-magnetic nanoparticles (MNPs-Fe₃O₄) on the expression of KCNQ₁ in cardiac muscle of mice at rest and at different times following a single bout of swimming (SBS). Firstly, we demonstrated that the expression levels of KCNQ₁ channels are significantly up-regulated in mice following a SBS by means of reverse transcription polymerase chain reaction (RT-PCR) and western-blot. After treating mice with normal saline or pure MNPs-Fe₃O₄ separately, we studied the potential effect of MNPs-Fe₃O₄ on the expression profile of KCNQ₁ in mouse cardiac muscle following a SBS. A SBS increased the transcription of KCNQ₁ at 3 hours post exercise (3PE) 164% ± 24% and at 12 hours post exercise (12PE) by 159% ± 23% (P < 0.05), and up-regulated KCNQ₁ protein 161% ± 27% at 12PE (P < 0.05) in saline mice. In MNPs-Fe₃O₄ mice, KCNQ₁ mRNA increased by 151% ± 14% and 147% ± 12% at 3 and 12 PE, respectively (P <0.05). Meanwhile, an increase of 152% ± 14% in KCNQ₁ protein was also detected at by 12PE. These results indicated that the administration of MNPs-Fe₃O₄ did not cause any apparent effects on the expression profile of KCNQ₁ in rested or exercised mice cardiac muscle. Our studies suggest a novel path of KCNQ₁ current adaptations in the heart during physical exercise and in addition provide some useful information for the biomedical application of MNPs which are imperative to advance nanomedicine.

Keywords:

• KCNQ₁
• cardiac muscle
• magnetic nanoparticles of Fe₃O₄

Acknowledgements

This work was supported by Special-Purpose Science Research Fund for the Doctoral Program of Higher Education of China (No. 20070286042) and National Nature Science Foundation of People’s Republic of China (No. 30770537, 30872970). The authors report no conflicts of interest in this work.

Disclosure

The authors report no conflicts of interest relevant to this study.