title: Lack of cardioprotection by single-dose magnesium prophylaxis on isoprenaline-induced myocardial infarction in adult Wistar rats.
abstract: OBJECTIVE
  Magnesium (Mg(2+)) is effective in treating cardiovascular disorders such as arrhythmias and pre-eclampsia, but its role during myocardial infarction (MI) remains uncertain. In this study, we investigated the effects of Mg(2+)pre-treatment on isoprenaline (ISO) -induced MI in vivo.
  
  
  METHODS
  Rats divided into four groups were each pre-treated with either MgSO4 (270 mg/kg intraperitoneally) or an equivalent volume of physiological saline, prior to the ISO (67 mg/kg subcutaneously) or saline treatments. One day post-treatment, the electrocardiogram and left ventricular blood pressures were recorded. Infarcts were determined using 2,3,5-triphenyltetrazolium chloride staining, and serum markers of lipid peroxidation were measured with spectrophotometric assays.
  
  
  RESULTS
  Mg(2+) pre-treatment neither altered the ISO-induced infarct size compared with ISO treatment alone (p > 0.05), nor reversed the low-voltage electrocardiogram or the prominent Q waves induced by ISO, despite a trend to decreased Q waves. Similarly, Mg(2+) did not prevent the ISO-induced decrease in peak left ventricular blood pressure or the decrease in minimal rate of pressure change. Mg(2+) did not reverse the ISO-induced gain in heart weight or loss of body weight. Neither ISO nor Mg(2+) altered the concentrations of lipid peroxidation markers 24 hours post MI induction.
  
  
  CONCLUSIONS
  Although Mg(2+) had no detrimental effects on electrical or haemodynamic activity in ISO-induced MI, the lack of infarct prevention may detract from its utility in MI therapy.
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Christie
authors.initials: C
authors.lastname: Garson
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Roisin
authors.initials: R
authors.lastname: Kelly-Laubscher
authors.affiliation: Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
authors.forename: Dee
authors.initials: D
authors.lastname: Blackhurst
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa. asfree.gwanyanya@uct.ac.za.
authors.forename: Asfree
authors.initials: A
authors.lastname: Gwanyanya
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D007274:Injections, Intraperitoneal; D007545:Isoproterenol; D015227:Lipid Peroxidation / Q000187:drug effects; D008278:Magnesium Sulfate / Q000008:administration & dosage*; D008297:Male; D009203:Myocardial Infarction / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D017208:Rats, Wistar; D013997:Time Factors; D016277:Ventricular Function, Left / Q000187:drug effects; D017725:Ventricular Pressure / Q000187:drug effects
chemical_list: D008278:Magnesium Sulfate; D007545:Isoproterenol