Whole blood chromium

Langard S, Gundersen N, Tsalev DL, et al. 1978. Whole blood chromium level and chromium excretion in the rat after zinc chromate inhalation. Acta Pharmacol Toxicol 42 142-149. 

An example of the many in vivo procedures using radioactive agents is the determination of whole-blood volume by injecting a known quantity of red blood cells labeled with radioactive chromium-51. After a suitable interval to allow the labeled cells to be distributed evenly throughout the body, a blood sample is taken, the amount of dilution of the 51Cr is measured, and the blood volume is calculated. Recall from Section 3.8 that when a concentrated solution is diluted, the amount of solute (51Cr in the present instance) remains the same and only the volume changes. That is,... 

Let s try an example. You know that chromium is a micronutrient that is an essential part of our diets. You might also remember that chromium pico-linate got a lot of attention several years ago as a magic weight-loss supplement. The Centers for Disease Control and Prevention lists normal chromium levels in blood as around 2.5 pg per 100 mL of whole blood. What is the concentration of chromium in parts per million You will need to know that the density of whole blood is 1.06 g/mL. 

Chromium can be measured in the hair, urine, serum, red blood cells, and whole blood. 

Amounts of total chromium were measured in lymphocytes, blood, and urine after intratracheal administration of either sodium dichromate(VI) or chromium(III) acetate hydroxide (a water-soluble chromium(III) compound) to male Wistar rats (Gao et al. 1993). The total amount of chromium administered was 0.44 mg Cr/kg body weight for each compound. The highest concentrations in tissues and urine occurred at 6 hours after treatment, the first time point examined. Mean chromium concentrations (n= 4 rats per time point) from treatment with chromium(III) were 56.3 pg/L in whole blood, 96 pg/L in plasma, 0.44 pg/1010 in lymphocytes, and 4,535.6 pg/g creatinine in urine. For treatment with chromium(VI) the levels were 233.2 pg/L for whole blood, 138 pg/L for plasma,... 

In an in vitro study, whole blood samples were spiked with water-soluble chromium(VI) or chromium(III) compounds. The results showed a greater level of chromium inside erythrocytes after treatment with chromium(VI) compounds, compared to chromium(III) compounds. The investigators reported that both chromium(VI) and chromium(III) compounds permeated the cell membrane, but only chromium(VI) compounds are taken up by erythrocytes and form complexes with intracellular proteins that could not be eliminated (Lewalter et al. 1985). 

For humans, the overall chromium(VI)-reducing/sequestering capacities were estimated to be 0.7-2.1 mg/day for saliva, 8.3-12.5 mg/day for gastric juice, 11-24 mg for intestinal bacteria eliminated daily with feces, 3,300 mg/hour for liver, 234 mg/hour for males and 187 mg/hour for females for whole blood, 128 mg/hour for males and 93 mg/hour for females for red blood cells, 0.1-1.8 mg/hour for ELF, 136 mg/hour for pulmonary alveolar macrophages, and 260 mg/hour for peripheral lung parenchyma. Although these ex vivo data provide important information in the conversion of chromium(VI) to reduced states, the values may over or under estimate the in vivo reducing capabilities (De Flora et al. 1997). 

Schermeier AJ, O Coimor LH, Pearson KH. Semi-automated determination of chromium in whole blood and serum by Zeeman electrothermal atomic absorption spectrophotometry. Clin Chem Acta 1985 152 123-34. 

The first requirement can be easily fulfilled by the preconcentration of the analyte before the analysis. Preconcentration has been applied to sample preparation for flame atomic absorption (25) and, more recently, for ICP (79,80) spectroscopy. However, preconcentration is not completely satisfactory, because of the increased analysis time (which may be critical in clinical analysis) and the increased chance of contamination or sample loss. Most important, however, a larger initial sample size is necessary. The apparent solution is a more sensitive technique. Table 2 lists concentrations of various metals in whole blood or serum (81,82) in comparison to limits of detection for the various atomic spectroscopy techniques. In many cases, especially for the toxic heavy metals, only flameless atomic absorption using a graphite furnace can provide the necessary sensitivity and accommodate a sample of only a few microliters (Table 1). The determination of therapeutic gold in urine and serum (83,84), chromium in serum (85), skin (86) and liver (87), copper in semen (88), arsenic in urine (89), manganese in animal tissues (90), and lead in blood (91) are but a few examples in analyses which have utilized the flameless atomic absorption technique. 

Christensen, J.M. and Pedersen, L.M. (1986). Enzymatic digestion of whole blood for improved determination of cadmium, nickel and chromium by electrothermal atomic absorption spectrophotometry Measurements in rheumatoid arthritis and normal humans. Acta Pharmacol. Toxicol. 59, 399-402. 

A methodology for the determination of chromium in whole blood, plasma, and erythrocytes based on the above method also gives reasonable analytical data with detection limits of 0.5 p,g/liter of whole blood [47]. 

Cavalleri et al. (1985) found that the half-life of Cr(VI) in rat whole blood and plasma in vivo was less than Imin. Chromium was administered intravenously as potassium dichromate in this study, and the observed half-life could have been influenced by specific physicochemical features of the salt (see Sect. C.IV). It is not known whether this is a representative half-life for systemic Cr(VI) administered by other routes. 

The distribution of chromium(III) in humans was analyzed using a whole-body scintillation scanner, whole-body counter, and plasma counting. Six individuals given an intravenous injection of 51chromium(III) as chromium trichloride had >50% of the blood plasma chromium(ni) distributed to various body organs within hours of administration. The liver and spleen contained the highest levels. After 3 months, the liver contained half of the total body burden of chromium. The study results indicated a three-compartment model for whole-body accumulation and clearance of chromium(III). The half-lives were 0.5-12 hours for the fast component, 1-14 days for the medium component, and 3-12 months for the slow component (Lim et al. 1983). 

In rats injected subcutaneously with 5.25 mg chromium(VI)/kg as potassium dichromate, most of the chromium in the tissues analyzed was found in the red blood cells with a peak level (63 pg chromium/g) achieved 24 hours after dosing. White blood cells were not analyzed for chromium content. Whole plasma contained 2.7-35 pg/mL, and the plasma ultrafiltrate contained 0.15-0.79 pg/mL. Tissue... 

Chromium is acquired from meats, whole-grain cereals, and brewer s yeast and plays a role in controlling non-insulin-dependent diabetes by normalizing blood glucose thereby increasing the effects of the body s insuhn on cells. Chromium 50 to 200 pg/d is considered within the normal range for children older than 6 years old and adults. 

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