Plasma glutathione peroxidase (GPx3) activity in the freshwater turtle Trachemys scripta elegans after isoflurane inhalation anesthesia

Introduction. Glutathione peroxidases are selenoenzymes which have a crucial role in the protection of animals against oxidative stress. Materials and Methods. From September 2017 to April 2018, a group of eight red-eared sliders were admitted at the Clinic for Small Animals, Faculty of Veterinary Medicine, University of Belgrade for elective diagnostic celioscopy. The turtles were of unknown age, weight from 1.20 kg to 1.86 kg. The anesthesia protocol involved using ketamine and medetomidine, both at a low dosage (10 mg kg-1 and 0.1 mg kg-1, respectively) as induction, after which anesthesia was maintained using isoflurane at 3% (vapor setting) in 100% oxygen (0.5 L min-1). Medetomidine was reversed with atipamezole (0.2 mg kg-1), given intramuscularly. The elective celioscopy was performed according to standard protocols. One day prior to anesthesia, heparinized blood samples were taken using the subcarapacial venous plexus for venipuncture. The second sampling took place three hours after the anesthetics were administered. Results and Conclusions. GPx3 activity in the blood plasmas (n=8) was measured by the coupled test as described by G?nzler et al. (1974). Data were tested for normality by the Shapiro-Wilk normality test and the groups were compared using a paired t-test. Blood plasma GPx3 activity was significantly higher (p=0.009) after a three-hour recovery period from inhalation anesthesia performed for elective diagnostic celioscopy, than before anesthesia. The measured post-anesthesia GPx3 activities were, on average, 80% higher than the measurements prior to anesthesia. It can be concluded that the statistically significant increase in the activity of plasma GPx3 from 91.02?36.05 mKat L-1 prior to anesthesia to 160.21?58.94 mKat L-1 three hours after anesthesia is due to the change in oxygen saturation. This is increased to 100% during the procedure, thus exposing the turtles to conditions of high oxygen saturation.