THE CATALYTIC PROPERTIES OF LACTATE DEHYDROGENASE IN SKELETAL MUSCLES AND LIVER OF THE MARSH FROG (PELOPHYLAX RIDIBUNDUS) DEPEND ON ITS ECOLOGICAL AND GEOGRAPHICAL LOCATION

Abstract

The marsh frog (Pelophylax ridibundus) has a widespread distribution range, which is due to a variety of adaptations that contribute to the development of tolerance to a wide range of physicochemical environmental factors. Of particular interest are the adaptations of these animals to different levels of oxygen in mid- and high-altitude conditions. In this work, a comparative analysis of the kinetic parameters of lactate dehydrogenase (LDH) in the liver of marsh frogs living in the mountainous and lowland regions of Dagestan was carried out. Animals caught in their habitats were decapitated, the liver and calf muscles were isolated, and they were placed in liquid nitrogen. In the laboratory, the selected tissues were homogenized and mitochondria-free cytosol was obtained by differential centrifugation, in which LDH activity was determined. It was found that LDH activity is significantly higher in the tissues of frogs from mountainous regions: by 42.4% in the muscles and 2.38 times in the liver (p 0.05). The high efficiency of catalysis is ensured due to significant changes in the catalytic parameters of the enzyme: an increase in Vmax (50.9% in muscles and 70% in the liver (p 0.05)) and a decrease in Km. (45.9% in muscles and 69% in liver, (p 0.05)). A more pronounced difference, compared to muscles, between LDH activity in the liver of foothill and lowland populations of frogs suggests that the sensitivity of liver LDH to changes in oxygen tension is higher. The vector of a number of other kinetic parameters of LDH (Ki, Sopt, Δ) in the liver of animals from mountainous landscapes is absolutely opposite to that of skeletal muscles. High activity and modifications of the catalytic properties of LDH in the tissues of marsh frogs living in mid-mountain areas may play an important role in the adaptation of these animals to conditions of oxygen deficiency.