[Seasonal differences in activity of tRNA and aminoacyl-tRNA synthetases of rabbit liver in myocardial ischemia].
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.


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.
Rodovicius
Hiliaras
H
Department of Biochemistry, Kaunas University of Medicine, Mickeviciaus 9, 3000 Kaunas, Lithuania. hiliaras@pascal.kmu.lt
D000409:Alanine / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D000818:Animals; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008250:Lysine-tRNA Ligase / Q000378:metabolism*; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism*; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism*; D011817:Rabbits; D012621:Seasons; D013997:Time Factors
D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D008250:Lysine-tRNA Ligase; D008239:Lysine; D000409:Alanine