The study aimed at evaluating short-term (24 h) in vivo effects of cadmium (Cd²⁺), zinc (Zn²⁺), and selenite ions (SeO₃^2–) on translational machinery in mouse liver. Activities of translation, tRNA^Leu and leucyl-tRNA synthetase (LRSase) were analysed by incorporations of [¹⁴C]-labeled leucine ([¹⁴C]-Leu) into specific products using liver preparations from mice after intraperitoneal (i.p.) injection of single doses of the following salts solutions: (1) CdCl₂ (1.6 mg Cd per 1 kg of body mass); (2) ZnSO₄ (3.1 mg Zn per 1 kg of body mass); (3) Zn-SO₄ and after 20 min CdCl₂ (amounts of respective elements indicated above); (4) Na₂SeO₃ (1.25 mg Se per 1 kg of body mass); (5) Na₂SeO₃ and after 20 min CdCl₂ (amounts of respective elements indicated before). In respect to control, time-dependent biphasic response of translation in the liver was determined following mice i.p. treatment with CdCl₂: diminution by 38% at 2 h followed by a 51% increase at 8 h and by a 32% decrease at 24 h. Neither Zn²⁺ nor SeO₃^2– caused remarkable alterations of translation activity when liver had been exposed to those ions for 2 h and 24 h. As compared to the control, Zn²⁺ and SeO₃^2– activated translation in mice liver by 67% and by 26% respectively in the 8-h period of exposure. Pretreatment with Zn²⁺ favoured the resistance of the translation system to Cd²⁺ only at 2 h, while pre-treatment with SeO₃² favoured such a resistance at 2 h and at 24 h of Cd intoxication. The acceptor activity of tRNA^Leu decreased by 44–74% and the activity of LRSase by 20–30% within a 24-h period following i.p. injection of CdCl₂. An exposure time-dependent decrease of tRNA^Leu acceptor activity versus an exposure time-dependent increase of LRSase activity were observed in the preparations from ZnSO₄-injected mouse liver. Mice pre-treatment with ZnSO₄ prevented activity of LRSase within 24 h against Cd-induced inhibition, but failed in the protection of the acceptor activity of tRNA^Leu. Responses of those translational components to SeO₃^2– were converse and biphasic: the maximum decreasing tRNA^Leu acceptor activity (by 66%) a with a simultaneous and insignificant increase of LRSase activity (by 12%), observed after 8 h, were followed by re-activation of tRNA and an insignificant decrease of LRSase activity after 24 h of liver exposure to Na₂SeO₃. In liver preparations from SeO₃^2– and Cd²⁺ co-treated mice, Cd inhibitory effects on tRNA^Leu were almost abolished within a 24-h period, whilst these effects manifested on LRSase at 2 h and were partly relieved at 8 and 24 h following the treatment.

Keywords: cadmium, zinc, selenium, translation, tRNA, leucyl-tRNA synthetase