Possible site of decreased intestinal zinc absorption in chronic uremic rats.

BACKGROUND/AIMS: Previous zinc tolerance tests in uremic patients indicated decreased intestinal zinc absorption. In the present study, a zinc tolerance test was initially applied to a uremic rat model and subsequently the possible site of malabsorption investigated.

METHODS

Chronic uremia was induced by five-sixths nephrectomy. Both control and nephrectomized rats were divided into three groups including animals with intact intestine, removal of the jejunum, and removal of the ileum. Each rat was orally loaded with zinc sulfate (80 mg/kg) in conscious state. Blood samples were drawn before and after zinc load at different intervals during 6 h for zinc analysis. The area under the plasma zinc curve (AUC) and the maximal increase of plasma zinc level (C(max)) were calculated.

RESULTS

Jejunectomy decreased both AUC and C(max) in control and nephrectomized rats, whereas ilectomized animals remained, interestingly, unchanged with regard to these two parameters. Significant decreases in both AUC and C(max) were observed in nephrectomized rats as compared with the control rats.

CONCLUSIONS

The jejunum is the main site of zinc absorption in response to a large oral load of zinc sulfate in both normal and uremic rats. The data further suggest that five-sixths nephrectomy reduces gastrointestinal zinc absorption in rats predominantly by the ileum.