Plasma ammonia and liver ornithine transcarbamoylase activity in zinc-deficient rats.

Abstract

The effects of zinc deficiency on the activity of hepatic ornithine carbamoyltransferase (OCT) and plasma ammonia were studied in rats. One group received (ad libitum) zinc-deficient diet containing 2 ppm zinc and the other group received a diet containing 110 ppm zinc (group pair-fed control) equal to the amount consumed by zinc-deficient rats during the previous 24 h. Rats were killed at weekly intervals. Blood urea nitrogen (BUN), plasma ammonia, and hepatic OCT activity were determined. By end of the 1st wk on zinc-deficient diet, the plasma ammonia levels became significantly higher than those of the controls and remained elevated thoughout the study period. BUN increased initially for 2 wk in the deficient rats, but by the end of 4 wk the levels were lower than in the controls. The hepatic OCT activity in deficient animals was significantly lowered as compared to the controls by the 3rd wk. It is concluded that an increase in plasma ammonia may occur as a result of deficiency of zinc.

Effect of Low Dietary Zinc During Late Gestation and Early Lactation on the Sow and Neonatal Piglets

“…Increased plasma ammonia has been reported in Zn-deficient rats (Rabbani and Prasad 1978) and in Zn-deficient men (Rabbani et al 1980). In this study, determinations of plasma ammonia in sows during pre-and postpartum period (Table 3) showed no significant difference (P>0.05) between the control and low Zn groups.…”

Experimental Zinc Deficiency in Humans

“…We have reported similar findings in zinc-deficient rats (16). This may have important health implications concerning zinc deficiency in man, because in liver disease hyperammonemia is believed to affect the central nervous system adversely.…”

Zinc in liver disease

“…Zinc may be involved in the pathogenesis of HE either by altering nitrogen and ammonia metabolism or by directly influencing brain functions. Rabbani and Prasad [46] demonstrated elevated levels of plasma ammonia and diminished activity of hepatic ornithine carbamyltransferase, a key enzyme in hepatic urea synthesis, in zinc-deficient rats. Increased levels of plasma ammonia in healthy human subjects as a result of dietary zinc restriction were reported by the same authors [20].…”