IMPAIRED ANTIOXIDANT DEFENSE IN GUINEA-PIG HEART TISSUES-TREATED WITHHALOTHANE

Purpose: To investigate the effects of halothane and halothane plus vi tamin E treatment on myocardial free radical metabolism in guinea pigs . Methods: Four groups of seven animals were studied; control, halotha ne, halothane plus vitamin E and vitamin E groups. In the halothane gr oup, halothane 1.5% in oxygen was given for 90 min over three days. In the halothane plus vitamin E group, 300 mg.kg(-1).day(-1) vitamin E i m was started three days before the first halothane treatment and cont inued for three days. Following sacrifice, the hearts were assayed for superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catal ase (CAT) and malondialdehyde (MDA) level was determined. Electron spi n resonance (ESR) analysis and electron microscopy (EM) were also perf ormed. Results: In the halothane group, SOD activities and MDA concent rations were increased compared with control and GSH-Px and CAT activi ties were decreased. In the halothane plus vitamin E group, there were no differences in enzyme activity compared with halothane alone but t he MDA level was decreased. In the vitamin E group, enzyme activities were increased compared with control. Mainly the CF3CHCl radical was i dentified by ESR analysis in heart tissues exposed to halothane and th e concentration of this radical was reduced by vitamin E. Electron mic roscopy showed cytoplasmic vacuolisation and dilation in sarcoplasmic reticulum in the heart tissues exposed to halothane:both were prevente d by vitamin E. Conclusion: Although halothane causes impairment in en zymatic antioxidant defence potential, due to lowered GSH-Px and CAT a ctivity, and accelerates peroxidative reactions in the tissues affecte d, no subcellular damage occurred. Vitamin E may protect tissues again st free radical attack by scavenging toxic free radicals formed in hea rt tissue during halothane anaesthesia.