title: Cardioprotective and Anti-arrhythmic Effects of Magnesium Pretreatment Against Ischaemia/Reperfusion Injury in Isoprenaline-Induced Hypertrophic Rat Heart.
abstract: The effects of magnesium (Mg2+) on ischaemic complications of pathological cardiac hypertrophy are unclear. In this study, we investigated effects of Mg2+pretreatment on ischaemia/reperfusion (I/R) injury in isoprenaline (ISO)-induced hypertrophic hearts. Wistar rats were treated for 7 days with different combinations of ISO (1.25 mg/kg) subcutaneously, MgSO4(270 mg/kg) intraperitoneally, or vehicle (saline). On the eighth day, hearts were either subjected to regional I/R during Langendorff perfusion or histologically stained with haematoxylin and eosin and Masson's trichrome. Haemodynamic and electrocardiographic parameters were recorded using the PowerLab data-acquisition system. Infarcts were identified by triphenyltetrazolium chloride staining. Plasma Mg2+was measured using photometric assays. Mg2+pretreatment significantly decreased I/R-induced infarct size (p = 0.001) and the overall arrhythmia score (p < 0.001) of I/R-induced ventricular ectopics, ventricular tachycardia, and ventricular fibrillation in hypertrophic hearts, but not non-hypertrophied hearts. Mg2+also improved post-I/R left ventricular developed pressure in hypertrophic hearts. However, Mg2+did not reverse the ISO-induced myocyte thickening and interstitial fibrosis or increases in heart weight. Plasma Mg2+was not different among treatment groups. These results suggest that Mg2+pretreatment may protect against I/R-induced injury and malignant arrhythmias in hypertrophic hearts, possibly via mechanisms unrelated to long-lasting changes in plasma Mg2+or prevention of structural changes such as fibrosis.
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925, South Africa.
authors.forename: Matthew
authors.initials: M
authors.lastname: Amoni
authors.affiliation: Department of Biological Sciences, Faculty of Science, University of Cape Town, Rondebosch, Cape Town, 7700, South Africa.|Academic Development Programme, Centre for Higher Education Development, University of Cape Town, Cape Town, South Africa.
authors.forename: Roisin
authors.initials: R
authors.lastname: Kelly-Laubscher
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925, South Africa.
authors.forename: Morea
authors.initials: M
authors.lastname: Petersen
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925, South Africa. asfree.gwanyanya@uct.ac.za.
authors.forename: Asfree
authors.initials: A
authors.lastname: Gwanyanya
mesh_terms: D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D006332:Cardiomegaly / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D019610:Cytoprotection; D004195:Disease Models, Animal; D005355:Fibrosis; D006329:Heart Conduction System / Q000187:drug effects / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D000067268:Isolated Heart Preparation; D007545:Isoproterenol; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009203:Myocardial Infarction / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D015428:Myocardial Reperfusion Injury / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000473:pathology; D017208:Rats, Wistar; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D000889:Anti-Arrhythmia Agents; D008278:Magnesium Sulfate; D007545:Isoproterenol
keywords: Arrhythmia; Cardiac; Hypertrophy; Ischaemia/reperfusion; Isoprenaline; Magnesium