EFFECT OF MODERATE HYPOTHERMIA ON LIPID-PEROXIDATION IN CANINE BRAIN-TISSUE AFTER CARDIAC-ARREST AND RESUSCITATION

Background and Purpose We sought to examine the effect of moderate hypothermia (30-degrees-C to 32-degrees-C) initiated after resuscitation on the scavenging systems of free radicals and lipid peroxidation in canine brain tissue after cardiac arrest and resuscitation. Methods Twenty-one dogs were divided into four groups: group A, nonischemic controls (shams) (n=4); group B, 15-minute cardiac arrest without reperfusion (n=4); group C, 15-minute cardiac arrest and standard resuscitation (n=6); and group D, 15-minute cardiac arrest and hypothermic resuscitation (n=7). During the period of 10 to 120 minutes after resuscitation, brain temperature and core temperature in group D remained at 30-degrees-C to 32-degrees-C and were 4-degrees-C to 5-degrees-C lower than in group C. For each dog, a sample of right parietal cerebral cortex was obtained from group A, group B, or from group C and group D at 2 hours after resuscitation. The sample was assayed for tissue malondialdehyde (MDA), the content of reduced glutathione (GSH), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX). Results In group B, a 15-minute cardiac arrest induced an increase in MDA, a significant reduction of GSH, and no change in SOD and GSH-PX activities compared with group A. In group C, there were further increases in MDA and reductions in GSH content and GSH-PX activity compared with group A; SOD activity remained substantially unchanged. The content of MDA was higher in group D than in group A but less elevated in group D than in group C. The GSH content and SOD and GSH-PX activities were significantly higher in group D than in group C. Conclusions Moderate hypothermia initiated after resuscitation can significantly inhibit the accumulation of lipid peroxidation products and the consumption of free radical scavengers in the brain tissue.