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5 . 2013

Correction of isoproterenol-induced myocardial injury with magnesium salts in magnesium-deficient rats

AbstractThe effect of Mg L-asparaginate (Mg-L-Asp), Mg chloride (MgCl2) and Mg sulfate (MgSO4) on the severity of isoproterenol-induced myocardial injury in Mg-deficient rats has been evaluated. To induce Mg deficiency, twenty-eight rats were placed on a low Mg diet (Mg content < 15 mg/kg) and demineralized water for 10 weeks. Twelve control rats were fed a basal control diet (Mg content = 500 mg/kg) and water (with Mg content 20 mg/l) for equal duration. On day 49 of low Mg diet, Mg-deficient rats were randomly divided into four groups: 1) group that continued to receive low Mg diet; 2) low Mg diet plus oral MgSO4; 3) low Mg diet plus oral Mg-L-Asp and 4) low Mg diet plus oral MgCl2 (50 mg of Mg per kg of body weight). Isoproterenol was injected subcutaneously (30 mg/kg BW, twice, at an interval of 24 hours) on the day 70 of the study, when plasma and erythrocyte Mg level in rats fed a low Mg diet were significantly decreased by 47% and 45% compared to intact animals. Twentyfour hours after second injection of isoproterenol, tests for activities of creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) were run and histopathological study was carried out. Administration of isoproterenol to rats resulted in significantly elevated plasma CK, LDH and AST, however, analyses in Mg deficient group demonstrated more dramatically increased activity of CK and AST compared to control rats (3,06 and 4,67 fold in Mg-deficient group vs. 1,91 and 3,92 fold in intact group). Increased leakage of cardiac injury markers was concomitant to increased volume of fuchsinophilic cardiomyocytes (54,2±1,7% in Mg-deficient group and 38,9±1,9% in intact group, p<0,05). However, pretreatment with of MgCl2, MgSO4 and Mg-L-Asp during 21 days favorably decreased sensitivity of myocardium to isoproterenolinduced ischemic injury. All evaluated salts significantly decreased myocyte marker enzymes as well as protected myocardium against isoproterenol-induced histopathological perturbations.

Keywords:isoproterenol, alimentary magnesium deficiency, myocardial ischemia, magnesium L-asparaginate, magnesium sulfate, magnesium chloride

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CHIEF EDITOR
CHIEF EDITOR
Viktor A. Tutelyan
Full Member of the Russian Academy of Sciences, Doctor of Medical Sciences, Professor, Scientific Director of the Federal Research Centre of Nutrition, Biotechnology and Food Safety (Moscow, Russia)

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