Abstract
Vagal nerve stimulation has been postulated to confer an antifibrillatory effect. We studied whether ghrelin administration would exert an antiarrhythmic effect via modulation of autonomic nerve activity in rats after acute myocardial ischemia (MI). Male Sprague-Dawley rats were exposed to 30 min of ischemia following ligation of the left coronary artery. Animals were then randomized to receive either ghrelin (n = 26) or saline (n = 26) during the period of coronary ligation. Power spectral analysis of heart-rate variability revealed that the administration of ghrelin increased the high-frequency (HF) power and decreased the low-frequency (LF)/HF ratio. Ventricular tachyarrhythmias were less frequent in rats after MI who received ghrelin in comparison with rats that received saline. Immunoblotting and immunohistochemistry revealed that rats given saline alone during MI exhibited a marked reduction in phosphorylated connexin-43 within the left ventricle, whereas those that received ghrelin displayed only minor reductions in comparison with sham-operated rats. These effects of ghrelin were diminished by the coadministration of atropine or the blockade of vagal afferents. These data demonstrate that the beneficial effect of ghrelin might be mediated by modulation of cardiac autonomic nerve activity.
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Acknowledgments
The authors thank Kazue Ishikawa for her assistance and contributions to the study. This study was supported by research grants from the Japan Society for the Promotion of Science (JSPS) and a Grant-in-Aid for Scientific Research (C) [JSPS (C)-21590899]. All authors have reported that they have no relationships to disclose relevant to the content of this article.
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Soeki, T., Niki, T., Uematsu, E. et al. Ghrelin protects the heart against ischemia-induced arrhythmias by preserving connexin-43 protein. Heart Vessels 28, 795–801 (2013). https://doi.org/10.1007/s00380-013-0333-2
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DOI: https://doi.org/10.1007/s00380-013-0333-2