Environmental cadmium exposure in the past and urinary levels of hydroxylysine glycosides.

Abstract

In our previous report (Hayakawa et al., 1987), it was suggested that there occurred some changes in the collagen metabolism among the inhabitants in a cadmium polluted area. The urinary total hydroxyproline (THP) excretion level of female inhabitants in the cadmium polluted area was significantly higher than that of the inhabitants in nonpolluted area, and a positive correlation was observed among the urinary levels of cadmium, T-HP and β2-microglobulin, though the correlation was low. However, it is known that urinary level of T-HP is influenced by the turnover of several tissue collagens other than bone. Therefore, for the confirmation of the above estimation, it is necessary to re-examine the results using the index of bone collagen turnover, which is known to be more reliable. Segrest and Cunningham (1970) pointed out that two hydroxylysine glycosides, 2-O-α-D-glucopyranosyl-O-β-D-galactopyranosyl.5- hydroxylysine (GGH) and O-β-galactopyranosyl-5-hydroxylysine (GH), are the endogenously derived collagen metabolites, not influenced by normal diet. The measurement of urinary GGH and GH levels provides a more quantitative indication in estimating the rate of collagen turnover because the amounts of GGH and GH differ according to the types of collagen and the kinds of tissue. In the present study, the relation between cadmium exposure and bone collagen metabolism reported in our previous study was further evaluated through the measurement of urinary GGH and GH levels in male inhabitants in the area where our previous survey was performed.