[Changes in plasma superoxide dismutase like activity during general anesthesia and surgery in man].

Superoxide radicals are highly reactive products that are known to induce various pathological changes in man. Superoxide dismutase is an enzyme that scavanges superoxide radicals. We measured plasma superoxide dismutase (SOD) like activity according to electron spin resonance using DMPO as a trap. The subjects of the study were 48 surgical patients who underwent various elective surgery. They ranged from 10 to 74 years in age. Anesthetic agents employed were enflurane in 50% O2 + 50% N2O, modified NLA with pentazocine, original NLA and fentanyl + ketamine (FK). In NLA group, 70% N2O and 30% O2 were given and 70% air and 30% O2 were administered to the patients of FK group. The mean plasma SOD like activity before the anesthetic induction in surgical patients of all groups was 5.70 +/- 0.41 U.ml-1. There is no significant difference compared with the value of normal persons. A marked reduction in plasma SOD like activity was obtained during surgery in any type of anesthesia in this study. Neither anesthetic agents used in this study nor the extent of surgery contributed to the degree of SOD like activity reduction. Surgical duration over two hours was the most contributing factor to reduce the SOD like activity. There was no correlation between plasma SOD like activity and age or serum total protein.