Seasonal differences in activity of rabbit liver tRNA and aminoacyl-tRNA synthetases specific for isoleucine and threonine under myocardial ischemia

Abstract

Activity of tRNA and aminoacyl-tRNA synthetases (AA-tRNA synthetases) in postribosomal supernatants from normal (control) rabbit liver and under 6, 12 and 24 h experimental myocardial ischemia (EMI) in autumn (September and October) and winter (December and January) have been compared. The results showed that acceptor activity of total tRNA for isoleucine and threonine under 6, 12 and 24 h EMI in autumn was higher by 18–29% than in winter. No differences were observed in acceptor activity of tRNA between normal groups of both seasons. The results of a study of AA-tRNA synthetase activities showed that the specific activity of isoleucyl- and threonyl-tRNA synthetases in liver under 6, 12 and 24 h EMI in autumn was higher by 17–37% than in winter. No differences in activity of aminoacyl-tRNA synthetases between normal groups of both seasons were observed. A decrease of tRNA acceptor activity under EMI in both seasons correlated with an increase of corresponding AA-tRNA synthetase activity which may be part of the compensatory mechanism of the cell to keep the normal range of protein synthesis under extreme conditions. Keywords: tRNA, aminoacyl-tRNA synthetases, protein synthesis, rabbit liver, seasons, myocardial ischemia