AJP - Endocrinology and Metabolism, Vol 244, Issue 2 122-E128, Copyright © 1983 by American Physiological Society
Zinc, iron, and copper absorption in the streptozotocin-diabetic rat
N. E. Craft and M. L. Failla
Altered tissue levels of trace metals have been reported in
streptozotocin-diabetic (STZ) rats. To determine whether increased hepatic
and renal levels of Cu and Zn were associated with enhanced intestinal
absorption, trace metal absorption was studied in control (C) and STZ rats
using dietary balance and in situ ligated-loop techniques. The apparent
daily absorption of dietary Zn and Cu per 100 g body wt was threefold
higher in STZ than C rats. In comparison, dietary Fe absorption per day was
not altered. Increased Zn absorption was closely correlated with
diabetes-associated polyphagia. The initial rate of injected 65Zn excretion
was more rapid in STZ rats, although the rate of excretion beyond day 7 was
similar from C and STZ animals. The quantity of Zn, Fe, and Cu absorbed per
20 cm duodenal loop was similar for C and STZ rats. Zn, Fe, and Cu
absorption per gram dry mucosa were reduced 45-53% in STZ rats due to the
50% increase in mucosal mass. Moreover, the quantity of radioisotopes
accumulated per gram dry mucosa and the concentration of metallothionein
per gram mucosal cytosol protein were similar in C and STZ animals.
Together, these data demonstrate that increased absorption of dietary Zn
and Cu is in part responsible for accumulation of these elements in STZ
tissues and suggest altered metal transport at the luminal (brush border)
surface of the intestinal epithelium.
