EFFECT OF SELENIUM AND GLUTATHIONE PEROXIDASE IN MYOCARDIAL PROTECTION IN INFANTS

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This study was undertaken to ascertain the reason why the myocardial protection was inferior in the infants to that in adults. The essential trace element, Selenium(Se), is a integral part of glutathione peroxidase(GSHPx). The rats were divided into three groups, first, infant rats 8-12 days after birth, Second, mature rats fed se-deficient diet (Se-deficient rats), third, mature rats fed normal diet (control rats). Serum Se level in infant rats (3.81 0.81 g/g protein) and in Se-deficient rats (2.06 1.69 g/g protein) was significantly lower than that in control rats (7.32 2.94 g/g protein)(p<0.01). Serum GSHPx activity in infant rats (22.7+3.5 U/g protein) and in Se-deficient rats (24.6+22.2 U/g protein) was significantly lower than that incontrol rats (179.6 12.0 U/g protein)(p<0.01).GHSPx activity in the heart in infant rats (0.48 0.11 U/mg protein)and in Se-defivient rats (0.34 0.03 U/mg protein) was significantly lower than that in control rats (0.80 0.06 u/mg protein) (p<0.01). However, Se lein the heart of infant rats was 5.1 times more than that of Se-deficient rats and control rats. Lipid peroxide level in Se-deficient rats (19.6 3.7 nM/mg protein) was significantly more than that incontrol rats (8.96 4.4 nM/mg protein)(&<0.01). Cardiac mechanical function was determined in isolated working heart in Se-deficient and control rats. After 30 minutes' perfusion following 63 minutes' cardiac arrest at 4 C, aortic pressure, cardiac output and LV dp/dt were significantly lower in Se-deficient rats (p<0.05). These results suggest that low GSHPx caused by disturbance of Se metabolism may more lipid peroxidation during reperfusion and poor myocardial protection in infants.