Metabolism of chromium

Onkelinx, C. 1977. Compartment analysis of metabolism of chromium (III) in rats of various ages. Amer. Jour. Physiol. 232 E478-E484. 

Doisy RJ, Streeten DHP, Souma ML, Kaiaeer MF, Rekant si and Daiakos TG (1971) Metabolism of chromium-51 in human subjects. In Mertz W and Comatzer WF, eds. Newer Trace Flements in Nutrition, pp. 155-168. Marcel Dekker Inc,... 

Age—It appears that the ability of the body to utilize inorganic salts of chromium decreases with aging. The problem appears to be related to the metabolism of chromium in the... 

Liu KJ, Shi X, Jiang J, Goda F, Dalai N, Swartz HM. 1996. Low frequency electron paramagnetic resonance investigation on metabolism of chromium(VI) by whole live mice. Ann Clin Lab Sci 26(2) 176-184. 

Metabolic Functions. Chromium (ITT) potentiates the action of insulin and may be considered a cofactor for insulin (137,138). In in vitro tests of epididymal fat tissue of chromium-deficient rats, Cr(III) increases the uptake of glucose only in the presence of insulin (137). The interaction of Cr(III) and insulin also is demonstrated by experimental results indicating an effect of Cr(III) in translocation of sugars into ceUs at the first step of sugar metaboHsm. Chromium is thought to form a complex with insulin and insulin receptors (136). 

Si NMR of hexamethyldisiloxane has been examined using a 750-MHz H resonance frequency, and a number of technical issues were discussed (Knight and Kinrade 1999). The use of chromium- acetylacetonate was used to reduce the Si relaxation time with a DEPT-45 pulse sequence. This indicated the potential application to the metabolism of organosilicon compounds. 

Chromium has proved effective in counteracting the deleterious effects of cadmium in rats and of vanadium in chickens. High mortality rates and testicular atrophy occurred in rats subjected to an intraperitoneal injection of cadmium salts however, pretreatment with chromium ameliorated these effects (Stacey et al. 1983). The Cr-Cd relationship is not simple. In some cases, cadmium is known to suppress adverse effects induced in Chinese hamster (Cricetus spp.) ovary cells by Cr (Shimada et al. 1998). In southwestern Sweden, there was an 80% decline in chromium burdens in liver of the moose (Alces alces) between 1982 and 1992 from 0.21 to 0.07 mg Cr/kg FW (Frank et al. 1994). During this same period in this locale, moose experienced an unknown disease caused by a secondary copper deficiency due to elevated molybdenum levels as well as chromium deficiency and trace element imbalance (Frank et al. 1994). In chickens (Gallus sp.), 10 mg/kg of dietary chromium counteracted adverse effects on albumin metabolism and egg shell quality induced by 10 mg/kg of vanadium salts (Jensen and Maurice 1980). Additional research on the beneficial aspects of chromium in living resources appears warranted, especially where the organism is subjected to complex mixtures containing chromium and other potentially toxic heavy metals. 

Venugopal, N.B.R.K. and S.L.N. Reddy. 1992a. Effect of bivalent and hexavalent chromium on renal and hepatic tissue glycogen metabolism of a fresh water teleost Anabas scandens. Environ, Monitor. Assess. 21 133-140. 

Nath, K. and Kumar, N. Hexavalent chromium toxicity and its impact on certain aspects of carbohydrate metabolism of the freshwater tel eost, Colisa fasciatus, Sci. Total Environ., 72 175-181, 1988. 

Most forms of Cr(III) are not absorbed and utilized by the body. For this reason, and because of the increased use of sucrose and other refined foods, a marginal human chromium deficiency may be widespread.604 605 This may result not only in poor utilization of glucose but also in other effects on lipid and protein metabolism.597 However, questions have been raised about the use of chromium picolinate as a dietary supplement. High concentrations have been reported to cause chromosome damage606 and there may be danger of excessive accumulation of chromium in the body.607... 

Not all of the various chemical forms of chromium are effective in improving sugar metabolism, and the exact nature of the compound or compounds involved in activating insulin is not established. Some of the chromium in plants may not be present in nutritionally effective forms. Il has not been established that chromium is essential to plants, but high concentrations of the metal are toxic. Most agricultural crops, especially their seeds, contain only low levels of chromium. 

Mertz DP, Koschnick R, Wilk G, et al. 1968. [Studies on the metabolism of trace elements in humans. I. Serum values for cobalt, nickel, silver, cadmium, chromium, molybdenum, manganese],... 

In humans and animals, chromium(ni) is an essential nutrient that plays a role in glucose, fat, and protein metabolism by potentiating the action of insulin (Anderson 1981). The biologically active form of chromium, called glucose tolerance factor (GTF), is a complex of chromium, nicotinic acid, and possibly amino acids (glycine, cysteine, and glutamic acid). Both humans and animals are capable of converting... 

Chromium(III) is an essential nutrient required for normal energy metabolism. The National Research Council recommends a dietary intake of 50-200 pg/day (NRC 1989). The biologically active form is an unidentified organic complex of chromium(ni) often referred to as GTF. Chromium(in) picolinate is a common form of chromium(III) nutritional supplementation. 

One PBPK model for chromium has been published. The O Flaherty model (O Flaherty 1993a, 1996) simulates the absorption, distribution, metabolism, elimination, and excretion of chromium(III) and chromium(VI) compounds in the rat. Two kinetic models describing the distribution and clearance of chromium(III) compounds in humans are described at the end of this section. 

The effects of chromium(III) chloride and sodium chromate(VI) on the hepatotoxicity of carbon tetrachloride exposure to mouse hepatocytes were examined by Tezuka et al. (1995). Primary cultures of mouse hepatocytes were pretreated with 10 or 100 pM chromium for 24 hours followed by exposure to 1-5 mM carbon tetrachloride for up to 1 hour. Chromium(VI) pretreatment significantly reduced the cell toxicity as well as lipid peroxidation caused by carbon tetrachloride. Chromium(III) pretreatment did not have any effect on cell toxicity. About 50% of chromium(VI) was taken up and reduced in the cells by 90% to chromium(III) within 10 minutes. The initial uptake rate of chromium(HI) into cells was greater than 500-fold less than chromium(VI), and only about 5% was absorbed. The protection against carbon tetrachloride damage by chromium(VI) was attributed to its rapid uptake and conversion to chromium(III), and it was determined that chromium(III) acts as a radical scavenger for the free radicals generated by carbon tetrachloride within the cell. Furthermore, chromium(VI) pretreatment reduced the activity of NADPH cytochrome c reductase which metabolizes carbon tetrachloride to reactive species. 

Differences in the intracellular metabolic pathways that result in the reduction of chromium(VI) will affect the nature of the reactive intermediates. For example, chelating ligands, such as glutathione and... 

Thus the metabolic reduction of chromium(VI) may represent bioactivation and/or detoxification. If a bioactivation process, intracellular reduction of chromium(VI) would lead to the ultimate toxic species. Conversely, if chromium(VI) is the toxic agent, effects would be elicited only if the amount of chromium(VI) entering target cells saturates the reducing mechanisms. 

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