Effects of selenium deficiency on the response of cardiac tissue to ischemia and reperfusion

Over a 10-week period, female Wistar rats received a diet containing a low level of selenium, cofactor of the antioxidant enzyme glutathione peroxidas e (GPx) in order to examine the influence of deficiency of this trace eleme nt (i) on tissue antioxidant enzyme defence systems, and (ii) on the suscep tibility of the myocardium to ischemia-reperfusion injury. At the end of th e dietary treatment, hearts were perfused at constant flow (11 ml/min) befo re being subjected to 15 min of global normothermic ischemia, followed by 3 0 min of reperfusion. The effects of selenium deficiency were estimated by studying functional recovery of various cardiac parameters (left ventricula r developed pressure LVDevP, heart late HR, and the product HR x LVDevP), a s well as ultrastructural tissue characteristics. Furthermore, super-oxide dismutase (SOD) and glutathione peroxidase (GPx activities were measured at the end of the reperfusion period. Results suggest that: (a) the activity of GPx is decreased by selenium deficiency while SOD activity remains uncha nged, rb) the recovery of cardiac function and myocardial ventricular ultra structure during repel-fusion are altered in the selenium-deficient group c ompared to controls. These results illustrate the crucial rule that seleniu m, the co-factor of one of the major antioxidant enzymes of the myocardium, plays in determining the vulnerability of the heart to ischemia and reperf usion. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.