The objective of this study was to examine the acceptor activities of tRNA for amino acids alanine and lysine and activities of corresponding aminoacyl-tRNA synthetases of normal rabbit liver 6, 12 and 24 h after experimental myocardial ischemia in different seasons of the year.
Material and methods: Male rabbits (2.5-3.5 kg) were used. Acute myocardial ischemia was induced by occlusion of the left anterior descending coronary artery. tRNA and aminoacyl-tRNA synthetases were isolated from normal (control) rabbit liver 6, 12 and 24 h after experimental myocardial ischemia in autumn (the months of September and October) and winter (the months of December and January). The acceptor activity of tRNA and activity of alanyl- and lysyl-tRNA synthetases were determined using 14C-labelled amino acids alanine and lysine.
Results: The results of study show that acceptor activity of rabbit liver tRNA for alanine and lysine under 6, 12 and 24 h experimental myocardial ischemia in autumn is higher by 18-52 percent than in winter. Activities of rabbit liver alanyl- and lysyl-tRNA synthetases under 6, 12 and 24 h experimental myocardial ischemia in autumn is less by 15-35 percent than in winter. No differences in activity of tRNA and aminoacyl-tRNA synthetases between normal groups of both seasons were observed.
Conclusions: The experimental data suggest that there are differences in acceptor activity of rabbit liver tRNA for alanine and lysine and in activity of alanyl- and lysyl-tRNA synthetases after 6, 12 and 24 h experimental myocardial ischemia. Decreasing of acceptor activity of tRNA for alanine under experimental myocardial ischemia in winter correlate with increasing of activity of alanyl-tRNA synthetase. Decreasing of acceptor activity of tRNA for lysine under experimental myocardial ischemia correlate with increasing of lysyl-tRNA synthetase activity in both studied seasons. It may be part of the compensatory mechanism of the cell to keep synthesis of protein in normal range under extreme conditions.