Protective Role of the Essential Trace Elements in the Obviation of Cadmium Toxicity: Glimpses of Mechanisms

Reference ranges for select elements and metals in healthy biomatrices

INTRODUCTION/OBJECTIVE

This review aimed to consolidate and compare reference values (RVs) for various elements and metals in biological samples from healthy populations worldwide.

METHODS

A Web of Science/PubMed/Scopus review was conducted. Original articles in the English language, from January 2012 to February 2022, with at least 120 participants and 3 evaluated elements, and biological samples of whole blood, serum, plasma, umbilical cord, and hair included in this review.

RESULTS

Ninety-nine studies were screened and assessed, and eventually, 29 eligible studies from 15 countries and a total recruitment of 26,676 healthy subjects, ages ranging from zero to 80 years were included in this review. The results of evaluating 36 trace/micro/meso/macro/ toxic metals and elements in biological fluids and hair were extracted from eligible studies. Several indicators include reference range (lower, upper), arithmetic and geometric mean, median, percentile (lower, upper), and confidence interval (CI) 95 % of evaluated elements were reported. Due to geographical conditions, different demographic factors, and different analytical methodologies, the results of the analysis were various in different countries.

CONCLUSIONS

This review points out the necessity for localized RVs and standardized methodologies for accurate clinical evaluations and bio-monitoring. The findings call for extensive studies across diverse populations to develop comprehensive RVs for elements and metals, ensuring effective health assessments and environmental exposure controls.

Heavy Metal Residues in Raw Cow Milk Collected from Three Major Cities of Odisha, India

Environmental pollution, particularly that caused by heavy metals, is a significant global concern in the current period of globalisation and possess a substantial risk to human and animal health through food chain. There have also been reports of heavy metal contamination of cattle and buffalo milk from various parts of India, including Tamilnadu, the Mumbai suburbs, and Northern Gujarat. However, no research has been done to determine whether cow milk from the study area in the state of Odisha contains heavy metal residues. Residue of heavy metals (arsenic, lead, cadmium, mercury and cobalt) in raw cow milk samples collected from three major cities of Odisha was studied. Arsenic was not detected in any of the milk samples. In the milk samples from Bhubaneswar, lead was detected higher than the permissible limit recommended by Codex standard and FSSAI, cadmium was detected close to the permissible limit recommended by Codex standard but below the limit recommended by FSSAI, cobalt and mercury were detected below the permissible limit recommended by Codex standard and FSSAI. In Cuttack and Puri, lead was detected close to the recommended permissible limit but other metals (viz. cadmium, cobalt and mercury) were below the recommended permissible limit. Among the three cities, heavy metals were detected highest in the milk samples from Bhubaneswar than Cuttack and Puri. Three of Odisha's largest cities-Bhubaneswar, Cuttack, and Puri-are rapidly becoming more urbanized and industrialized, with populations and automobiles increasing. This might contaminate water and soil, which would then poison the food chain. This could be the primary way that heavy metals enter the animal body, which would then contaminate milk and animal food. The Pb and Cd residues detected in cow milk from the study areas were alarming. It suggested that the cows reared by Goalas in these study areas do not produce environmentally safe and suitable milk for human consumption.

Recent advances in the clinical management of intoxication by five heavy metals: Mercury, lead, chromium, cadmium and arsenic

Metals have been used for many centuries, but their nutritional and toxic effects have been investigated since the last century. The common toxic heavy metals (THM) include mercury, lead, chromium cadmium, and arsenic. As human exposure to THM increasingly causes systemic and organ complications, it seems required to review the recent advances of treatment of the toxic metals. Despite the current knowledge of the hazards of heavy metals, there is still high incidents of their poisonings particularly in developing countries. In this review, after an introduction, we briefly describe the routes of exposure, clinical features and prognosis of each metal poisoning. Then, review the different treatments for each metal with particular attention to recent advances in the treatment of both acute and chronic poisonings. The main antidotes for all THM are still chelating agents, but new agents were developed over the past decades and have been used successfully for the THM poisonings. Dimercaptosuccinic acid (DMSA) known as succimer has been prescribed as a safe oral chelator in lead poisoning. Similarly, dimercapto-propanesulfonic acid (DMPS) has also revealed fewer side effects than the old chelating agents. The two are currently gaining increased acceptance among clinical toxicologists. However, there is no specific antidote for mercury poisoning. Dimercaprol is almost no longer used as an antidote of choice in the treatment of chronic THM poisoning. Comparison of clinical management of intoxication by the five heavy metals reveals similar treatment strategies. On the other hand, some of them require specific interventions to reduce the toxicity. Because of drawbacks in the application of commonly known chelating agents, treatment with bioactive compounds which have antioxidant and anti-inflammatory properties has been the subject of much interest in recent research. However, despite the promising results observed in experimental animals, clinical trials on their clinical therapeutic benefits have not been yet successful and need further studies to determine their efficacy and safety in humans. Development of less toxic chelating agents are still under investigations. Moreover, the development of orally administrable chelating agents for home health care would likely be of great interest for future research.

Metabolomics analyses and comparative insight to neuroprotective potential of unripe fruits and leaves of Citrus aurantium ethanolic extracts against cadmium-induced rat brain dysfunction: involvement of oxidative stress and akt-mediated CREB/BDNF and GSK3β/NF-κB signaling pathways

Serious neurological disorders were associated with cadmium toxicity. Hence, this research aimed to investigate the potential neuroprotective impacts of the ethanolic extracts of Citrus aurantium unripe fruits and leaves (CAF and CAL, respectively) at doses 100 and 200 mg/kg against cadmium chloride-provoked brain dysfunction in rats for 30 consecutive days. HPLC for natural pigment content revealed that CAF implied higher contents of Chlorophyll B, while the CAL has a high yield of chlorophyll A and total carotenoid. Fifty-seven chromatographic peaks were identified by UPLC/MS/MS; 49 and 29 were recognized from CAF or CAL, respectively. Four compounds were isolated from CAF: 3',4',7 -trihydroxyflavone, isorhainetin, vitexin, and apigenin. In vitro studies outlined the antioxidant capacity of studied extracts where CAF showed better scavenging radical DPPH activity. Results clarified that both extracts with a superior function of CAF at the high adopted dose significantly ameliorated CdCl2-induced neuro-oxidative stress and neuro-inflammatory response via restoring antioxidant status and hindering nuclear factor kappa B (NF-κB) stimulation. Moreover, it up-regulated the levels of phospho-protein kinase B (p-Akt), phospho- cAMP-response element binding protein (p-CREB), and brain-derived neurotropic factor (BDNF) levels, and elicited a marked decrease in the content of glycogen synthase kinase 3 beta (GSK3β), besides amending Caspase-3 and hyperphosphorylation of tau protein in brain tissues. Moreover, a significant improvement in the rats' behavioral tasks of the CAL and CAF-treated groups has been recorded, as indicated by marked preservation in locomotion, exploratory, and memory functions of the experimental rats. In conclusion, the reported neuroprotective impacts of C. aurantium extracts may be through modulating p-AKT/p-CREB/BDNF and / or p-Akt/ GSK3β/NF-κB signaling pathways.

Iron Administration Partially Ameliorates Cadmium-Induced Oxidative Damage in the Liver and Kidney of Rats

The protective effect of Fe against Cd-induced toxicity in the liver and kidney of rats during concurrent administration of both metals was investigated in this study. Fifty female rats (130-150 g) were distributed into five groups of 10 rats each (n = 10): Group I (control), received normal saline solution; Group II (1.2 mg CdCl2/kg b.w.); Group III (1.2 mg CdCl2 + 0.25 mg FeCl2/kg b.w.); Group IV (1.2 mg CdCl2 + 0.75 mg FeCl2/kg b.w.); and Group V (1.2 mg CdCl2 + 1.5 mg FeCl2/kg b.w.). Administration of both tested substances lasted for 47 days. Cd was injected intraperitoneally once a week, while Fe was administered to the Cd-exposed animals by oral gavage thrice weekly. The animals were killed at the end of the study, their blood was collected, and their liver and kidneys were harvested for biochemical and histological analysis. Following Cd administration, the kidney and liver showed a significant increase in Cd concentration, while Fe concentration in the kidney decreased. However, cotreatment with Fe decreased Cd concentration in the kidney and liver and increased Fe concentration in the kidney but not the liver, and the effect was more pronounced in the higher than lower doses. In the kidney, cotreatment with Fe especially at higher doses inhibited Cd-induced lipid peroxidation and plasma uric acid concentration. In the liver, lipid peroxidation which Cd did not alter was found to be elevated after cotreatment with the highest dose Fe. Inflammatory cell infiltrations of the central vein and renal tubular and glomeruli injury induced by Cd were not obviated by Fe cotreatment. It seems that both tissues respond differently to the concurrent administration of these metals and that Fe protected the kidney against oxidative injury-induced by Cd but not histopathological changes in both tissues.

Protective effect of honokiol on cadmium-induced liver injury in chickens

Cadmium (Cd), a highly toxic heavy metal in the environment, poses a significant threat to livestock and poultry farming. Honokiol (HNK), a Chinese herbal extract with potent antioxidant activity, acts through oxidative damage and inflammation. Cd induces oxidative stress and causes liver damage in animals. However, whether HNK can alleviate Cd-induced liver injury in chickens and its mechanism remains unclear. In this study, the 48 chickens were randomly allocated into 4 groups, control group, Cd group (70 mg/kg Cd), HNK group (200 mg/kg HNK) and Cd + HNK group (70 mg/kg Cd+200 mg/kg HNK). Results showed that HNK improved the Cd induced reduction in chicken body weight, liver weight, and liver coefficient. HNK recovered the Cd induced liver damaged through increased serum liver biochemical indexes, impaired liver oxidase activity and the disordered the expression level of antioxidant genes. HNK alleviated Cd induced pathological and ultrastructure damage of liver tissue and liver cell that leads apoptosis. HNK decreased Cd contents in the liver, Cd induced disturbances in the levels of trace elements such as iron, copper, zinc, manganese, and selenium. HNK attenuated the damage to the gap junction structure of chicken liver cells caused by Cd and reduced the impairment of oxidase activity and the expression level of antioxidant genes induced by Cd. In conclusion, HNK presents essential preventive measures and a novel pharmacological potential therapy against Cd induced liver injury. Our experiments show that HNK can be used as a new green feed additive in the poultry industry, which provides a theoretical basis for HNK to deal with the pollution caused by Cd in the poultry industry.

Effect of Genotype on Cadmium and Trace Element Accumulation in Wheat from Weakly Alkaline Cadmium-contaminated Soil

Cadmium (Cd) contamination of farmland soils leads to Cd accumulation in crops and reduced micronutrient uptake, posing grave risks to food safety. Herein, we investigated the enrichment and transportation patterns of Cd and trace elements in different parts of six wheat genotypes grown in weakly alkaline Cd-contaminated soils via pot experiments. The results revealed that the wheat grain variety with high Cd accumulation (Ningmai13) demonstrated a 1.94-fold increase compared to the variety with low accumulation (Yanong0428). The transfer factor of Cd from wheat straw to grain ranged from 0.319 to 0.761, while the transfer factor of Cd from root to straw ranged from 0.167 to 0.461. Furthermore, the concentrations of other metals in wheat grains followed the order of Zn > Mn > Fe > Cu. There was a significant positive correlation between Cd and Mn in grains, indicating a potential synergistic effect. Overall, this study provides valuable insights into the regulation of micronutrient intake to modulate Cd uptake in wheat.

Cadmium Stress Signaling Pathways in Plants: Molecular Responses and Mechanisms

Heavy metal (HM) pollution, specifically cadmium (Cd) contamination, is a worldwide concern for its consequences for plant health and ecosystem stability. This review sheds light on the intricate mechanisms underlying Cd toxicity in plants and the various strategies employed by these organisms to mitigate its adverse effects. From molecular responses to physiological adaptations, plants have evolved sophisticated defense mechanisms to counteract Cd stress. We highlighted the role of phytochelatins (PCn) in plant detoxification, which chelate and sequester Cd ions to prevent their accumulation and minimize toxicity. Additionally, we explored the involvement of glutathione (GSH) in mitigating oxidative damage caused by Cd exposure and discussed the regulatory mechanisms governing GSH biosynthesis. We highlighted the role of transporter proteins, such as ATP-binding cassette transporters (ABCs) and heavy metal ATPases (HMAs), in mediating the uptake, sequestration, and detoxification of Cd in plants. Overall, this work offered valuable insights into the physiological, molecular, and biochemical mechanisms underlying plant responses to Cd stress, providing a basis for strategies to alleviate the unfavorable effects of HM pollution on plant health and ecosystem resilience.

Zinc mitigates cadmium-induced sperm dysfunction through regulating Ca2+ and metallothionein expression in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a highly toxic heavy metal element that might adversely affect sperm function such as the acrosome reaction (AR). Although it is widely recognized that zinc (Zn) plays a crucial role in sperm quality, the complete elucidation of how Zn ameliorates Cd-induced sperm dysfunction is still unclear. In this study, we aimed to explore the protective effects of Zn against the sperm dysfunction induced by Cd in the freshwater crab Sinopotamon henanense. The results demonstrated that Cd exposure not only impaired the sperm ultrastructure, but also caused sperm dysfunction by decreasing the AR induction rate, acrosome enzyme activity, and Ca2+ content in sperm while elevating the activity and transcription expression of key Ca2+ signaling pathway-related proteins Calmodulin (CAM) and Ca2+-ATPase. However, the administration of Zn was found to alleviate Cd-induced sperm morphological and functional disorders by increasing the activity and transcription levels of CaM and Ca2+-ATPase, thereby regulating intracellular Ca2+ homeostasis and reversing the decrease in Ca2+ contents caused by Cd. Furthermore, this study was the first to investigate the distribution of metallothionein (MT) in the AR of S. henanense, and it was found that Zn can reduce the elevated levels of MT in crabs caused by Cd, demonstrating the significance of Zn in inducing MT to participate in the AR process and in metal detoxification in S. henanense. These findings offer novel perspectives and substantiation regarding the utilization of Zn as a protective agent against Cd-induced toxicity and hold significant practical implications for mitigating Cd-induced sperm dysfunction.

Luteolin Alleviates Cadmium-Induced Kidney Injury by Inhibiting Oxidative DNA Damage and Repairing Autophagic Flux Blockade in Chickens

Chickens are a major source of meat and eggs in human food and have significant economic value. Cadmium (Cd) is a common environmental pollutant that can contaminate feed and drinking water, leading to kidney injury in livestock and poultry, primarily by inducing the generation of free radicals. It is necessary to develop potential medicines to prevent and treat Cd-induced nephrotoxicity in poultry. Luteolin (Lut) is a natural flavonoid compound mainly extracted from peanut shells and has a variety of biological functions to defend against oxidative damage. In this study, we aimed to demonstrate whether Lut can alleviate kidney injury under Cd exposure and elucidate the underlying molecular mechanisms. Renal histopathology and cell morphology were observed. The indicators of renal function, oxidative stress, DNA damage and repair, NAD+ content, SIRT1 activity, and autophagy were analyzed. In vitro data showed that Cd exposure increased ROS levels and induced oxidative DNA damage and repair, as indicated by increased 8-OHdG content, increased γ-H2AX protein expression, and the over-activation of the DNA repair enzyme PARP-1. Cd exposure decreased NAD+ content and SIRT1 activity and increased LC3 II, ATG5, and particularly p62 protein expression. In addition, Cd-induced oxidative DNA damage resulted in PARP-1 over-activation, reduced SIRT1 activity, and autophagic flux blockade, as evidenced by reactive oxygen species scavenger NAC application. The inhibition of PARP-1 activation with the pharmacological inhibitor PJ34 restored NAD+ content and SIRT1 activity. The activation of SIRT1 with the pharmacological activator RSV reversed Cd-induced autophagic flux blockade and cell injury. In vivo data demonstrated that Cd treatment caused the microstructural disruption of renal tissues, reduced creatinine, and urea nitrogen clearance, raised MDA content, and decreased the activities or contents of antioxidants (GSH, T-SOD, CAT, and T-AOC). Cd treatment caused oxidative DNA damage and PARP-1 activation, decreased NAD+ content, decreased SIRT1 activity, and impaired autophagic flux. Notably, the dietary Lut supplement observably alleviated these alterations in chicken kidney tissues induced by Cd. In conclusion, the dietary Lut supplement alleviated Cd-induced chicken kidney injury through its potent antioxidant properties by relieving the oxidative DNA damage-activated PARP-1-mediated reduction in SIRT1 activity and repairing autophagic flux blockade.

Can the Toxic Heavy Metals Be Beneficial at Trace Levels? Understanding Their Outranged Biological Functions

Heavy metal toxicity poses a serious danger to the environment and its inhabitants on a global scale. The harmful heavy metals that are not necessary but are still dangerous, such as lead, arsenic, cadmium, and mercury are frequently linked to pollution and the resulting health problems. Despite several gross ill effects, toxic heavy metals have been found to show beneficial biological activity when applied at very low or trace levels. This article aims to collate such investigations conducted during the last two decades with trace levels of cadmium, mercury and arsenic toxicity against animal systems. There are a total of 13 pre-clinical works demonstrating the protective or beneficial effect of mercury, cadmium and arsenic at trace levels. Such literature reports with lead could not be found. From the outcome of the current literature investigation it is evident that, trace levels of toxic heavy metals namely arsenic, cadmium and mercury possess remarkable protective and beneficial effects chiefly on growth, developmental and reproductive parameters against animal systems pre-clinically, in contrast to their known toxic effects-operated by multiple mechanisms which provided some empirical support for further understanding of the outranged biological functions of the heavy metals. Further mechanistic works on this sphere may pave the way for a better understanding of the protective role of toxic heavy metals for the accomplishment of animals including humans.

Lead, Cadmium, and Arsenic in Raw Cow's Milk in a Central Andean Area and Risks for the Peruvian Populations

Milk and its derivatives are basic foods in Peru, especially for children. The Junín region, in the central Andes, is one of the leading dairy basins. However, the safety of milk is affected by mining-metallurgical activities, wastewater dumping, organic residues, and inappropriate use of organophosphate fertilizers in agriculture whose contaminants reach the food chain, putting human health at risk. The purpose of this study was to evaluate the bioaccumulation of lead (Pb), cadmium (Cd), and arsenic (As) in milk produced on a representative farm in central Peru, which uses phosphorous agrochemicals and is adjacent to a small mineral concentrator and a municipal solid waste dump, and to evaluate the potential risk for the Peruvian population of 2-85 years considering three levels of daily intake by age, which constitutes the innovative contribution of the study. These three elements were quantified by flame atomic absorption spectrometry following standardized procedures. The mean contents of Pb (0.062 mg/kg), Cd (0.014 mg/kg), and As (0.030 mg/kg) in milk exceeded the maximum limits allowed by international standards. At all ages, the target quotient hazard followed a descending order of As > Pb > Cd, being > 1 in the case of As. The hazard index was >1 for children under 7, 9, and 11 years of age in the scenarios of low, medium, and high milk intake. The information is valid for formulating policies to prevent adverse health effects and develop standards and awareness programs, monitoring, and control of heavy metals in milk in Peru.

Interaction between mitophagy, cadmium and zinc

Mitophagy is the selective degradation of mitochondria by autophagy. This process is considered to be one of the stages of mitochondrial quality control, as a result of which damaged depolarized mitochondria are eliminated, thus limiting the formation of reactive oxygen species and the release of apoptogenic factors. Selective degradation of mitochondria by autophagy is one of the main ways to protect cells from cadmium toxicity, which results in dysfunction of the mitochondrial electron transport chain, leading to electron leakage, production of reactive oxygen species and cells death. However, excessive autophagy can be dangerous for cells. Currently, the participation of cadmium ions in normal physiological processes has not been detected. Zn²⁺, unlike Cd²⁺, regulate the activity of a large number of functionally important proteins, including transcription factors, enzymes, and adapters. It has been shown that Zn²⁺ not only participate in autophagy, but are also crucial for basal or induced autophagy. It is likely that zinc drugs can be used to reduce the cadmium toxicity and in the regulation of mithophagy.

Integrated transcriptome and metabonomic analysis of key metabolic pathways in response to cadmium stress in novel buckwheat and cultivated species

INTRODUCTION

Buckwheat (Fagopyrum tataricum), an important food crop, also has medicinal uses. It is widely planted in Southwest China, overlapping with planting areas remarkably polluted by cadmium (Cd). Therefore, it is of great significance to study the response mechanism of buckwheat under Cd stress and further develop varieties with excellent Cd tolerance.

METHODS

In this study, two critical periods of Cd stress treatment (days 7 and 14 after Cd treatment) of cultivated buckwheat (Pinku-1, named K33) and perennial species (F. tatari-cymosum Q.F. Chen) (duoku, named DK19) were analyzed using transcriptome and metabolomics.

RESULTS

The results showed that Cd stress led to changes in reactive oxygen species (ROS) and the chlorophyll system. Moreover, Cd-response genes related to stress response, amino acid metabolism, and ROS scavenging were enriched or activated in DK19. Transcriptome and metabolomic analyses highlighted the important role of galactose, lipid (glycerophosphatide metabolism and glycerophosphatide metabolism), and glutathione metabolism in response to Cd stress in buckwheat, which are significantly enriched at the gene and metabolic levels in DK19.

DISCUSSION

The results of the present study provide valuable information for a better understanding of the molecular mechanisms underlying Cd tolerance in buckwheat and useful clues for the genetic improvement of drought tolerance in buckwheat.

Exposure to essential and non-essential trace elements and risks of congenital heart defects: A narrative review

Congenital heart defects (CHDs) are congenital abnormalities involving the gross structures of the heart and large blood vessels. Environmental factors, genetic factors and their interactions may contribute to the pathogenesis of CHDs. Generally, trace elements can be classified into essential trace elements and non-essential trace elements. Essential trace elements such as copper (Cu), zinc (Zn), iron (Fe), selenium (Se), and manganese (Mn) play important roles in human biological functions such as metabolic function, oxidative stress regulation, and embryonic development. Non-essential trace elements such as cadmium (Cd), arsenic (As), lead (Pb), nickle (Ni), barium (Ba), chromium (Cr) and mercury (Hg) are harmful to health even at low concentrations. Recent studies have revealed the potential involvement of these trace elements in the pathogenesis of CHDs. In this review, we summarized current studies exploring exposure to essential and non-essential trace elements and risks of CHDs, in order to provide further insights for the pathogenesis and prevention of CHDs.

The Effect of Smoking Habits on Blood Cadmium and Lead Levels in Residents Living Near a Mining and Smelting Area in Northwest China: a Cross-Sectional Study

Few studies have focused on environmental cadmium (Cd) and lead (Pb) exposure while exploring the effect of smoking on blood Cd (BCd) and blood Pb (BPb) levels. Moreover, essential trace elements affect the absorption, accumulation, and toxicity of Cd and Pb. To investigate the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and the influence of essential trace elements on the effect, 301 residents living near a mining and smelting area in Northwest China were included in our study. After collecting health information and measuring BCd, BPb, serum iron, magnesium, and total calcium levels, we analyzed the association between smoking and BCd and BPb levels and the influence of the essential trace elements on the association. The results showed that BCd and BPb levels in smokers were significantly higher than those in non-smokers. There was a dose-response association between pack-years and the odds ratios (ORs) of high BCd and BPb levels in all participants compared with non-smokers. Serum iron, magnesium, and calcium had a negative effect on the elevations of the ORs of high BCd and BPb levels. In addition, smoking-related elevations of BCd and BPb levels vary by sex, age, BMI, and age of smoking initiation. Our findings present evidence for the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and may provide guidance for the prevention and control of BCd and BPb elevations in residents living in Cd- and Pb-polluted areas.

Honey Can Obviate Heavy Metal Toxicity: A Review

Toxicity caused by heavy metals inflicts a grave global menace to the habitat and inhabitants. Arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) are the non-essential yet harmful heavy metals commonly associated with pollution and resultant health complications. Typical chelating/complexing agents are not worthy of combating heavy metal-induced sub-chronic and chronic toxicities. It transpires from scientific data mining that, honey obviates investigational heavy metal toxicity. This review aims to collate such investigations conducted against As, Cd, and Pb toxicity. There is a total of 19 pre-clinical works demonstrating the ameliorative effect of honey against empirical As, Cd, and Pb toxicity. Pre-clinical reports against Hg and clinical study against these heavy metals could not found. From the outcome of the current literature investigation, it seems that honey has a marked heavy metal toxicity meliorative effect which is chiefly ascribed to its innate antioxidant effect due to its diverse polyphenol content.

Cadmium chloride generates cytotoxic reactive species that cause oxidative damage and morphological changes in human erythrocytes

Cadmium chloride (CdCl₂₎ is a widely used industrial compound that exhibits multiple organ toxicity. Cadmium is transported through blood where erythrocytes are exposed to its action. Here the effect of CdCl₂ on human erythrocytes was examined under in vitro conditions. Human erythrocytes were treated with 0.01-0.5 mM CdCl₂ for 24 h at 37 °C. Lysates were made from CdCl₂ treated and untreated (control) cells and used for further analysis. CdCl₂ treatment resulted in marked hemolysis of erythrocytes and oxidation of hemoglobin to methemoglobin. This will result in anemia and also reduce the oxygen carrying ability of erythrocytes. Hemoglobin oxidation was accompanied by degradation of heme and release of free ferrous iron moiety. Further analysis showed elevated lipid hydroperoxides and formation of advanced oxidation protein products along with reduction in total sulfhydryl content, indicating the generation of oxidative stress condition in the cell. Incubation of erythrocytes with CdCl₂ enhanced generation of reactive oxygen and nitrogen species, decreased the antioxidant power and inhibited pathways of glucose metabolism. Plasma membrane was damaged as indicated by enhanced osmotic fragility and inhibition of membrane bound enzymes. This was confirmed by electron microscopy which showed formation of echinocytes. These results show that CdCl₂ generates reactive species which impair the antioxidant system resulting in oxidative damage to erythrocytes.