Effects of cadmium and zinc ions on mitotic activity and protein synthesis in mouse liver.
OBJECTIVE
To evaluate the in vivo effects of cadmium and zinc ions on mitotic activity and protein synthesis in mouse liver.


METHODS
White outbred mice were injected intraperitoneally with cadmium chloride solution (14 micromoles cadmium per 1 kg of body mass) and/or with zinc sulfate solution (48 micromoles zinc per 1 kg of body mass). Histological slides were examined by light microscopy. For each specimen, the number of mitotic cells was counted in 10 randomly selected reference areas. Protein synthesis was evaluated by incorporation of [14C]-labeled leucine into newly synthesized peptides and proteins.


RESULTS
We found that the mitotic index of mouse liver cells was increased for periods of 2-8 h after cadmium chloride injection; after 24 h the mitotic index significantly diminished. These data indicate a possible increase in liver cell regeneration during the initial 8 h following acute cadmium exposure. Zinc ions did not affect liver mitotic activity, and, interestingly, decreased the mitotic index in the liver of cadmium-treated mice to control levels. An examination of the kinetics of protein synthesis in mouse liver over a 24 h period after cadmium chloride injection revealed that incorporation diminished by 38% at 2 h, then increased 51% by 8 h and again decreased by 32% at 24 h as compared to control. Zinc ions increased protein synthesis in mouse liver 8 h after zinc sulfate injection. In assessing the effects of cadmium and zinc ions in vivo, it appeared that zinc ions tended to protect protein synthesis in response to cadmium ions but only at 2 h after cadmium intoxication.


CONCLUSIONS
Zinc ions are capable of normalizing an increase in the mitotic index of liver cells at the early stage of cadmium poisoning (up to 8 h) and to protect the liver translation machinery against inhibition by cadmium.
Institute for Biomedical Research, Kaunas University of Medicine, Eiveniu 4, 50009 Kaunas, Lithuania. alina@kmu.lt
Alina
A
Smalinskiene
Rasa
R
Gaileviciūte
Vaiva
V
Lesauskaite
Ilona
I
Sadauskiene
Oleg
O
Abdrakhmanov
Leonid
L
Ivanov
D000818:Animals; D019256:Cadmium Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D002105:Cadmium Poisoning / Q000378:metabolism* / Q000517:prevention & control; D003627:Data Interpretation, Statistical; D007274:Injections, Intraperitoneal; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008115:Liver Regeneration; D051379:Mice; D008938:Mitosis / Q000187:drug effects*; D008940:Mitotic Index; D014176:Protein Biosynthesis / Q000187:drug effects*; D012996:Solutions; D013997:Time Factors; D015032:Zinc / Q000494:pharmacology*; D019287:Zinc Sulfate / Q000008:administration & dosage / Q000494:pharmacology
D012996:Solutions; D019287:Zinc Sulfate; D015032:Zinc; D019256:Cadmium Chloride