The effect of chromium on parameters related to iron metabolism

Abstract

The effect of chromium on some parameters related to iron metabolism was investigated. Preliminary experiments showed that this metal ion was taken up by serum proteins and was dependent on the amount of chromium present in the medium. It was also shown that the uptake of iron was reduced significantly in the presence of chromium. In vivo study showed that the serum levels of iron and total iron binding capacity (TIBC) were reduced by 28 and 11%, respectively, following daily administration of chromium (1 mg/kg) for 45 d. Serum ferritin was reduced by 22% under this condition. Hematocrit and hemoglobin levels were also affected in chromium-treated animals and were both reduced by 17%. Spectrophotometric titration of each individual amino acid located in the iron binding site of transferrin revealed that tyrosine might be the most suitable ligand for the binding of chromium to transferrin. These results suggest that chromium may compete with iron in binding to apo-transferrin, and influence iron metabolism and its related biochemical parameters.

A comparison of the insulin-sensitive transport of chromium in healthy and model diabetic rats

“…Rat transferrin was obtained from ICN. 51 Cr 2 -transferrin was prepared as previously described [22]. In short, apotransferrin was prepared by treatment of the diferric form with EDTA (ethylenediaminetetraacetic acid)-containing buffer as described in [28].…”

“…In humans, transferrin is maintained on average only approximately 30% loaded with iron and consequently has been proposed to potentially carry other metal ions [15]. In vitro studies of the addition of chromic ions to isolated apotransferrin reveal that Cr(III) readily binds to the two-metal-binding sites, resulting in intense changes in the proteinÕs ultraviolet spectrum [16][17][18][19][20][21][22]. This spectral change has been used recently to determine effective binding constants of chromium to transferrin, K 1 ¼ 1:42 Â 10 10 M À1 and K 2 ¼ 2:06 Â 10 5 M À1 [23].…”

The trail of chromium(III) in vivo from the blood to the urine: the roles of transferrin and chromodulin

“…The similar charge and ionic radii of chromic ions compared to ferric ions suggests that chromic ions should bind relatively tightly to the protein. In vitro studies of the addition of chromic ions to isolated transferrin reveal that Cr(III) readily binds to the two metal-binding sites, resulting in intense changes in the protein's ultraviolet spectrum [19,20,21,22,23,24,25]. These spectral changes have been used recently to determine effective binding constants of chromium to transferrin, K 1 =1.4210 10 M ±1 and K 2 =2.0610 5 M ±1 [26].…”

Changes in serum parameters associated with iron metabolism in male rat exposed to lead

“…Cadmium also induced iron deficiency in rats [6]. Changes in ironrelated parameters in rats, which were exposed to chromium and/or aluminum, have been also reported [1,30,31]. Moreover, other elements such as gallium, nickel, indium, and cobalt may have significant effects on iron metabolism [28,29,[32][33][34]36].…”

“…It is now well evidenced that due to the chemical similarities between iron and some other trace elements such as chromium, cadmium, indium, and aluminum, they enter blood circulation and bind to serum Trf and interfere with the biochemical pathways of iron [1,3,31,33,34]. On the other hand, the inhibitory effects of Pb 2+ on other molecules have been already reported [35,47].…”