Possible Role of Catalase in Adaptation to Diving of Semi-Aquatic Rodents Ondatra zibethica

Physiological role of catalase in mechanisms of adaptive reactions to hypoxic influences in diving rodents, muskrats Ondatra zibethica, has been investigated. The myocardial tissues were established to be the most resistant to the oxidative stress produced by hypobaric hypoxia-reoxygenation. An intraperitoneal injection of a specific nonreversible catalase inhibitor, 3-amino-1, 2, 4-triazol (3-AT), at a dose of 1 g/kg body weight, on the background of the diving hypoxia-reoxygenation decreased the catalase activity in liver, kidney, heart, and brain tissues, on average, by 83%. No statistically significant changes of this activity were observed in the femoral muscle tissue. In 56.5 min after the injection, the tissue concentrations of 3-AT in liver, kidney, heart, and femoral muscle were approximately similar to amount to about 1 µg/mg wet tissue. The 3-AT concentration in the brain was three times lower than in other tissues; however, this practically did not affect the extent of catalase inhibition. During the diving hypoxia-reoxygenation the reduction of catalase activity under effect of 3-AT was accompanied by an increase of lipid peroxidation (LPO) only in the heart and liver, which indicates an important role of catalase in protection of these tissues from damaging effects of active oxygen forms at resumed external respiration after the long diving.