[Pathogenic factors of postischemic ventricular dysfunction and effects of magnesium].
To investigate the mechanism of myocardial; tunning, a Langendorff model of rat hearts (n = 18) underwent 15 min ischemia with coronary flow at 0.2 ml/min and 10 min reperfusion with Ringer's solution of 1.06 mmol/L Mg2+. Histological exam revealed no myocardial necrosis. However, the recovery of pressure product (RPP) was only 77% compared with control period. The myocardial Ca2+ content and water content were significantly increased (P < 0.01, vs control hearts). Pretreatment with high concentration of Mg2+ (2.4 mmol/L) improved the recovery of postischemic ventricular function, attenuated the Ca2+ overload and myocardial edema. The results indicated that a brief period of low-flow ischemia could produce a postischemic ventricular dysfunction-the myocardial stunning. Calcium overload and myocardial edema might be two pathogenic factors. An increased Mg2+ had a protective effects on postischemic ventricular dysfunction, which may involve the following mechanisms: reduced Ca2+ overload and attenuated myocardial edema.
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D000818:Animals; D002118:Calcium / Q000378:metabolism; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000503:physiopathology; D017682:Myocardial Stunning / Q000378:metabolism*; D009206:Myocardium / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D016277:Ventricular Function, Left / Q000187:drug effects*
D008274:Magnesium; D002118:Calcium