The significance of glutathione peroxidase on myocardial protection in the rat hearts: the key of clarify the cause of vulnerability to reperfusion injury in infantile cardiac operations.

Selenium (Se) is an integral component of glutathione poeroxidase (GSHPx), and the serum selenium concentration is age-depend. We speculated that myocardial GSHPx had relation to reperfusion injury in open heart operations, especially in infants in whom GSHPx activity is low. This study correlated GSHPx activity with the serum and myocardial selenium concentrations in Wistar rats, which were divided into three groups, infants, Se-deficient rats, and control rats. Serum GSHPx activity in infant and Se-deficient rats (22.7 +/- 3.5 U/g protein, 24.6 +/- 22.2 U/g protein) was lower than that in controls (179 +/- 12.0 U/g protein). The serum selenium concentration in infant and Se-deficient rats (3.81 +/- 0.81 micrograms/g protein, 2.06 +/- 1.69 micrograms/g protein) was also lower than that in controls (7.32 +/- 2.96 micrograms/g protein). The myocardial GSHPx activity was significantly lower in infants and Se-deficient rats (4.76 +/- 1.05 x 10(-1) U/mg protein, 3.38 +/- 0.32 x 10(-1) U/mg protein) than that in controls (8.03 +/- 0.57 x 10(-1) U/mg protein). However, the myocardial selenium concentration in infants (1.42 +/- 0.24 x 10(-1) micrograms/mg protein) was significantly higher than that in the other groups (0.31 +/- 0.06 x 10(-1) micrograms/mg protein, 0.28 +/- 0.04 x 10(-1) micrograms/mg protein). Next, in Se-deficient and control rats, isolated hearts were perfused for aerobically with Krebs-Henseleit solution in the Langendorff mode for 15 minutes, followed by 60 minutes of global ischemia at 4 degrees C and then reperfused for 30 minutes in a working mode. The hemodynamic parameters were measured.(ABSTRACT TRUNCATED AT 250 WORDS)