Changes in Na+/K+-ATPase Activity and Biomembrane Lipid Composition in Smolts of Pink Salmon Oncorhynchus gorbuscha (Salmonidae) during Their Downstream Migration in the Indera River (White Sea Basin)

The article presents the results of the study of the activity of Na+/K+-ATPase and the content of individual lipid components associated with the regulation of the activity of this enzyme in smolts of pink salmon Oncorhynchus gorbuscha during their downstream migration from the Indera River to the White Sea. Changes in both the enzyme activity and values of a number of lipid parameters have been recorded in an experiment in which the juveniles were kept for 24 and 72 h in river (at a salinity of less than 1‰), estuarine (6‰), and sea (30‰) water in cages established in their natural habitat. The results suggest that the increased resistance of pink salmon individuals to changes in environmental factors (salinity and temperature) during downstream migration to estuarine and sea water is accompanied by a change in the activity of Na+/K+-ATPase, which significantly increased in the experiment after 24-h stay of juveniles in sea water and less significantly increased after 24-h stay in the estuarine water. The prolongation of exposure to the estuarine and sea water to 72 h did not induce a further increase in Na+/K+-ATPase activity in pink salmon individuals. The revealed changes in the lipid content in the experimental groups can be determined not only by changes in the environmental factors, but also by the physiological and biochemical state of the juveniles.