Zinc is an essential trace metal in the body. It's deficiency is known to induce skin lesions and hypogeusia. It also has an important role as a core element of various enzymes. In the liver, ornithine carbamyl transferase (OCT), a metal enzyme in the urea cycle, where ammonium is metabolized, contains zinc. The previous report showed that patients with liver cirrhosis (LC) were in a state of zinc deficiency. The present study investigated the possible involvement of hypozincemia in the functional failure of the urea cycle in hepatic insufficiency in rats with experimental LC. Compared with control rats, rats with LC showed a decrease in the serum zinc concentration (LC 118.6 +/- 33.7 micrograms/dl: control 161.6 +/- 13.9 micrograms/dl p less than 0.05), a decrease in the zinc content of the liver (LC 81.4 +/- 16.3 micrograms/g DW: control 108.1 +/- 6.9 micrograms/g DW p less than 0.01), a decrease in the OCT activity in the liver (LC 24.7 +/- 4.0 U/mg prot: control 42.4 +/- 3.8 U/mg prot p less than 0.01), and an increase in serum ammonium (LC 87.2 +/- 38.5 micrograms/dl: control 38.5 +/- 10.6 micrograms/dl p less than 0.05). There was a significant correlation between the zinc content and OCT activity in the cirrhotic liver (r = 0.6075, p less than 0.01). In addition, to evaluate the effect of dietary zinc on rats with LC, we divided these rats into two groups and fed them a diet with or without zinc for 4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)