Involvement of cholinoceptors in cadmium-induced endothelial dysfunction

Short-term Effects of Cadmium Exposure on Blood Pressure and Vascular Function in Wistar Rats

Chronic cadmium exposure is known to be associated with vascular changes and increased blood pressure, but its short-term effects on the cardiovascular system remain poorly understood. This study aimed to investigate the pressoric and vascular effects of a 7-day exposure to CdCl2 in Wistar rats. The rats were divided in control group (Ct), which received tap water, and the Cd group, which received a 100 mg/L CdCl2 solution via drinking water for 7 days. We analyzed body weight, plasma Cadmium concentration, systolic blood pressure (SBP), and vascular responses. Despite relatively low plasma Cadmium concentration, the Cd group exhibited elevated SBP and increased contractile response to phenylephrine. Endothelium removal and NOS inhibition increased contractions in both groups. In the Cd group's aorta, we observed enhanced levels of phospho-eNOS (Ser1177) and basal NO release. Cd group showed reduced Catalase expression and increased basal release of H2O2, with catalase reducing the contractile response. In arteries pre-contracted with phenylephrine, Cd group showed impaired endothelium-dependent (Acetylcholine) and independent (sodium nitroprussiate-SNP) relaxation responses. However, responses to SNP were similar after pre-contraction with KCl in both groups. These data suggest early effects of Cadmium on blood pressure and aortic function, indicating impaired H2O2-scavenging by catalase. Increased H2O2 due to Cadmium exposure might explain heightened responses to phenylephrine and weakened relaxation responses mediated by the NO-K+-channels pathway. Our findings shed light on Cadmium's short-term impact on the cardiovascular system, providing insights into potential mechanisms underlying its effects on blood pressure regulation and vascular function.

Association between urinary cadmium level and subclinical myocardial injury in the general population without cardiovascular disease aged ≥ 50 years

Cadmium (Cd) is a toxic heavy metal linked to an increased risk of cardiovascular disease (CVD). But the relationship between urinary Cd (U-Cd) and electrocardiographic subclinical myocardial injury (SC-MI) in older people is unclear. This study evaluated the connection between U-Cd and SC-MI in people who did not have CVD. The study involved 4269 participants from the National Health and Nutrition Examination Survey III(NHANES III) aged ≥ 50 years and had no history of CVD. The relationship between U-Cd and cardiac infarction/injury score (CIIS) was assessed by multivariable linear regression. Whether U-Cd and SC-MI were correlated was determined by multivariate logistic regression, restricted cubic spline, and subgroup analysis. There was a significant association between U-Cd and CIIS (β, 1.04, 95% confidence interval (CI): 0.39-1.69; P = 0.003) in the highest quartile and fully adjusted model. After adjusting for relevant confounders, multivariable logistic regression showed that participants in the highest quartile of U-Cd had a greater chance of having SC-MI than those in the first ( OR (95% CI), 1.37(1.13,1.66), P for trend = 0.003), and this relationship was especially strong among hypertensive participants. And a positive linear correlation between U-Cd and the prevalence of SC-MI was shown by restricted cubic spline analysis. U-Cd may be a novel risk element for SC-MI because it is independently and linearly linked to CIIS and SC-MI.

Effects of heavy metals on cardiovascular diseases in pre and post-menopausal women: from big data to molecular mechanism involved

To assess the link between a mixed heavy metal (cadmium, lead, and mercury) and the 10-year risk of cardiovascular diseases (CVDs) in pre- and post-menopausal Korean women aged ≥20 years, as well as identify potential molecular mechanisms of mixed heavy metal-induced CVDs. Multivariate linear regression, weighted quantile sum (WQS) regression, quantile g-computation (gqcomp), and Bayesian kernel machine regression (BKMR) models were used to examine the effects of mixed heavy metals and the 10-year risk of CVDs. The Comparative Toxicogenomics Database, MicroRNA ENrichment TURned NETwork, and the microRNA sponge generator and tester were used as the key data-mining approaches. In our BKMR analysis, we found that the overall effect of mixed heavy metals was linked to the 10-year risk of CVDs in postmenopausal women in the upper 20^th percentiles and in premenopausal women in the upper 55^th percentiles. Mercury was identified as the key chemical for the 10-year risk of CVDs in pre- and postmenopausal women. In silico analysis revealed that a heavy metal mixture interacted with six genes associated with CVD development. Physical interactions (77.6%) were found to be the most common among CVD-related genes induced by the heavy metals studied. Several pathways have been identified as the main molecular mechanisms that could be affected by studied heavy metals and are implicated in the development of CVDs (e.g., lipid and lipoprotein metabolism, lipoprotein metabolism, cholesterol metabolism, and cardiovascular disease). ALB, APOE, ATF5, and CREB3L3 were the key genes and transcription factors related to CVDs induced by the mixture of the investigated heavy metals, respectively. The two miRNAs with the highest interaction and expression in the development of CVDs were hsa-miR-199a-5p and hsa-miR-199a-3p. We also designed and tested miRNA sponge sequences for these miRNAs. The cutoff thresholds for each heavy metal level linked with the 10-year risk of CVDs were described. A mixture of heavy metal exposures, especially mercury, was more strongly linked with the 10-year risk of CVDs in postmenopausal women than in premenopausal women. Early interventions in postmenopausal women should be considered to reduce CVD risks.

Kaempferol prevents cadmium chloride-induced liver damage by upregulating Nrf2 and suppressing NF-κB and keap1

This study evaluated the protective effect of kaempferol, a natural flavonoid, against cadmium chloride (CdCl₂)-induced liver damage and examined the possible anti-inflammatory and antioxidant mechanisms of protection. Adult male rats were divided into 4 groups (each of 8 rats) as control, kaempferol (50 mg/kg/day orally), CdCl₂ (15 ppm/day), and CdCl₂ (15 ppm/day) + kaempferol (50 mg/kg/day). All treatments were given for 30 days. With no effect on attenuating the reduced food intake, kaempferol significantly increased body weight and lowered serum levels of liver injury markers including bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyltransferase 1 (γ-GTT1) in the CdCl₂-treated rats. It also restored normal liver architectures, prevented hepatocyte, loss, and swelling and reduced inflammatory cell infiltration. These effects were associated with a reduction in mitochondrial permeability transition pore, as well as in the expression of cytochrome-c and cleaved caspase-3, markers of mitochondrial damage, and intrinsic cell death. In both the control positive and CdCl₂-treated rats, kaempferol significantly lowered the hepatic levels of reactive oxygen species, malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), Interleukine-6 (IL-6), and the nuclear activity and localization of NF-κB p65. Besides, kaempferol significantly increased the hepatic total and nuclear levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1, as well as levels of superoxide dismutase (SOD) and reduced glutathione (GSH) but reduced the cytoplasmic protein levels of keap1. In conclusion, the protective effect of kaempferol against CdCl₂-induced hepatic damage is mediated by antioxidant and anti-inflammatory effects driven by upregulating Nrf2/HO-1 axis and suppressing the NF-κB p65 and keap1.

Effects of heavy metals on hypertension during menopause: a Korean community-based cross-sectional study

OBJECTIVE

To examine the associations between serum cadmium, lead, and mercury and hypertension in pre- and postmenopausal women.

METHODS

Serum heavy metal (cadmium, lead, and mercury) levels were analyzed in 7,226 randomly selected women who participated in Korean National Health and Nutrition Examination Surveys from 2009 to 2017. Odds ratios (ORs) for hypertension were calculated for log2-transformed serum heavy metal levels, median tertile levels of serum cadmium, mercury, and lead, and for interactions between heavy metal levels and tertiles, after covariate adjustment.

RESULTS

A doubling of serum cadmium was associated with hypertension in premenopausal (OR 2.47; 95% CI, 1.01-6.10, P = 0.049) and postmenopausal women (OR 1.70; 95% CI, 1.02-2.84, P = 0.043), and significant trends were observed for cadmium tertiles (P < 0.01). In premenopausal women, a two-fold increase in serum mercury increased the OR of hypertension by 3.08 (95% CI, 1.12-8.43, P = 0.029), and significant trends were also observed for serum mercury tertiles (P < 0.01). Interactions between serum cadmium, lead, and mercury levels in pre- and postmenopausal women were found to impact the prevalence of hypertension.

CONCLUSION

Given increasing exposure to heavy metals in Korea, further prospective study is needed to identify associations between heavy metal exposures, both separately and in combination, with the prevalence of cardiovascular disease risk factors in well-characterized cohorts of different populations and to determine means of preventing heavy metal exposure.

Association between heavy metals, high-sensitivity C-reaction protein and 10-year risk of cardiovascular diseases among adult Korean population

The prevalence of cardiovascular diseases (CVDs) in Korea tends to be increasing. It has worsened during the COVID-19 pandemic. Increasing evidence shows heavy metals are associated with increased CVD risk. We aimed to determine the association between the serum heavy metal levels and 10-year risk of CVDs and to predict risks of CVDs based on marginal effects. Heavy metals were measured by a graphite furnace atomic absorption spectrometry and direct mercury analyzer. The results show a significant relationship between the increase in cadmium, lead, mercury, hs-CRP levels and the 10-year risk of CVD after adjustment for serum cotinine, age group, sex, body mass index, a family history of CVDs, diabetes or hyperlipidemia, high-risk drinking, physical activity, and diabetes. A doubling of serum cadmium, lead, mercury, and hs-CRP was associated with the increase in the 10-year risk of CVD by 0.14%, 0.10%, 0.11% and 0.22%, respectively. Therefore, a special concern should be given to the harmful impacts of heavy metals on the 10-year risk of CVD. It is important to develop a prevention strategy targeting the high-risk population to slow down this progression to risk factors related to heavy metals and reduce prevalence. Remarkedly, hs-CRP is the most validated and widely used inflammatory marker, and could be a potential clinical value in predicting and monitoring CVDs.

Cadmium and atherosclerosis: A review of toxicological mechanisms and a meta-analysis of epidemiologic studies

Cadmium has been proposed to be the one of the factors of atherosclerosis development, although the existing data are still controversial. The primary objective of the present study is the review and the meta-analysis of studies demonstrating the association between Cd exposure and atherosclerosis as well as review of the potential mechanisms of such association. We performed a systematic search in the PubMed-Medline database using the MeSH terms cadmium, cardiovascular disease, atherosclerosis, coronary artery disease, myocardial infarction, stroke, mortality and humans up through December 20, 2017. Elevated urinary Cd levels were associated with increased mortality for cardiovascular disease (HR = 1.34, 95% CI: 1.07-1.67) as well as elevated blood Cd levels (HR = 1.78, 95% CI: 1.24-2.56). Analysis restricted to never smokers showed similar, though more imprecise, results. Consistently, we also observed an association between Cd exposure markers (blood and urine) and coronary heart disease, stroke, and peripheral artery disease. Moreover, Cd exposure was associated with atherogenic changes in lipid profile. High Cd exposure was associated with higher TC levels (OR = 1.48, 95% CI: 1.10-2.01), higher LDL-C levels (OR = 1.31, 95% CI 0.99-1.73) and lower HDL-C levels (OR = 1.96, 95% CI: 1.09-3.55). The mechanisms of atherogenic effect of cadmium may involve oxidative stress, inflammation, endothelial dysfunction, enhanced lipid synthesis, up-regulation of adhesion molecules, prostanoid dysbalance, as well as altered glycosaminoglycan synthesis.

The association between cadmium and lead exposure and blood pressure among workers of a smelting industry: a cross-sectional study

BACKGROUND

Lead and cadmium are harmful heavy metals that are used for a variety of occupational purposes. Considering their potentially hazardous effects on health, studies on the association between exposure to these two heavy metals and health disorders have been actively conducted. This study aimed to determine the association between blood lead and cadmium levels and blood pressure in workers exposed to lead and cadmium in a smelter.

METHODS

Nine hundred and sixty-three male workers who worked in a smelter, and underwent medical examinations at the Ulsan University Hospital between January 1 and December 31, 2014, were selected as participants. Among them, 310 subjects whose data on height, weight, blood pressure, fasting blood glucose, lipid profile, and blood lead and cadmium levels were available and who answered the questionnaire were selected as the final participants. We investigated the drinking habit, smoking status, exercise adequacy, and family history of hypertension of these workers using formal questionnaires. A statistical analysis was conducted using Student's t-test, analysis of variance, and linear or logistic regression.

RESULTS

The association between blood lead and cadmium levels and blood pressure was analyzed through statistical adjustment of the risk factors of hypertension. Results showed an association between blood cadmium level and blood pressure elevation. However, blood lead level was found to be not correlated with blood pressure elevation.

CONCLUSIONS

This study shows the association between blood cadmium level and systolic blood pressure (SBP) and diastolic blood pressure (DBP) elevation.

TRIAL REGISTRATION

IRB No. 2017-03-037. Retrospectively Registered 30 March 2017.

The impact of subchronic cadmium poisoning on the vascular effect of nitric oxide in rats

The aim of this study was to evaluate the impact of poisoning with cadmium in hypertensive doses (50 or 200 ppm in drinking water for three months) on the basal and stimulated release NO effect in the isolated and perfused rat mesenteric bed. Mesenteric artery preparation preconstricted by norepinephrine (0.5 μg/mL) was used to determine changes in its vascular resistance induced by e-NOS synthase blocker, N-ω-nitro-L-arginine (L-NOARG) injected in increasing doses from 1.0 to 200.0 μg or acetylcholine (ACh) administered in doses from 0.05 × 10-10 to 5.0 × 10-10 mol before and during L-NOARG infusion (1.0 μg/mL). Vascular reactivity was measured as an increase or decrease in perfusion pressure in the constant flow system.

Rats poisoned with 50 or 200 ppm of cadmium demonstrated a significant decrease (P < 0.05) in vascular response to L-NOARG used in doses of 50 or 100 μg. The dose-response curve obtained for L-NOARG was shifted to the right and ED50 value was greater in the group of rats given cadmium in a dose of 200 ppm than in the controls (70.39 ± 10.7 versus 25.79 ± 4.8 μg, P < 0.01). These rats reacted with lower expressed vasodilatation to ACh in doses to 0.2 ± 10-10 mol. In all poisoned rats, L-NOARG enhanced the effect of ACh used in doses from 0.05 to 0.5 ± 10-10 mol, whereas in the control group this effect was only achieved at 0.1 ± 10-10 mol. The serum nitric oxide concentration was decreased (P B < 0.05) in both groups of cadmium-treated rats. These results suggest that cadmium in hypertensive doses modifies the vascular effect of NO in basal conditions and after stimulation by ACh.

Oxidative Stress and Cardiovascular Dysfunction Associated with Cadmium Exposure: Beneficial Effects of Curcumin and Tetrahydrocurcumin

Cadmium (Cd) is a non-essential heavy metal with high toxicity potential. Humans are exposed to Cd present in diet, polluted air, and cigarette smoke. Cd exposure has been associated with increased risk of chronic diseases, including hypertension, atherosclerosis, diabetes, and nephropathy, all of which could be attributable to dysfunctional endothelial and smooth muscle cells. Cd toxicity is correlated with increased reactive oxygen formation and depletion of antioxidants, resulting in an oxidative stress. Chelation of Cd has proved useful in the removal of the Cd burden. However, several chelating agents cause side effects in clinical usage. Recent studies have shown that the antioxidant compounds curcumin and tetrahydrocurcumin can alleviate vascular dysfunction and high blood pressure caused by Cd toxicity. In chronic Cd exposure, these antioxidants protect vascular endothelium by increasing nitric oxide (NO•) bioavailability and improving vascular function. Antioxidant activity against Cd intoxication results directly and/or indirectly through free radical scavenging, metal chelation, enhanced expression of the antioxidant defense system, regulation of inflammatory enzymes, increase in NO• bioavailability, and reduction of gastrointestinal absorption and tissue Cd accumulation. This review summarizes current knowledge of Cd-induced oxidative stress and cardiovascular dysfunction and a possible protective effect conferred by the antioxidants curcumin and tetrahydrocurcumin.

Changes in compact bone microstructure of rats subchronically exposed to cadmium

Background

Chronic exposure to cadmium (Cd), even at low concentrations, has an adverse impact on the skeletal system. Histologically, primary and secondary osteons as basic structural elements of compact bone can also be affected by several toxicants leading to changes in bone vascularization and mechanical properties of the bone. The current study was designed to investigate the effect of subchronic peroral exposure to Cd on femoral bone structure including histomorphometry of the osteons in adult male rats.

In our study, 20 one-month-old male Wistar rats were randomly divided into two experimental groups. In the first group, young males received a drinking water containing 30 mg of CdCl₂/L, for 90 days. Ten one-month-old males without Cd intoxication served as a control group. After 90 days of daily peroral exposure, body weight, femoral weight, femoral length, cortical bone thickness and histological structure of the femora were analysed.

Results

We found that subchronic peroral application of Cd had no significant effect on body weight, femoral length and cortical bone thickness in adult rats. On the other hand, femoral weight was significantly increased (P < 0.05) in Cd-intoxicated rats. These rats also displayed different microstructure in the middle part of the compact bone where vascular canals expanded into central area of substantia compacta and supplied primary and secondary osteons. Additionally, a few resorption lacunae which are connected with an early stage of osteoporosis were identified in these individuals. Histomorphometrical evaluations showed that all variables (area, perimeter, maximum and minimum diameter) of the primary osteons’ vascular canals, Haversian canals and secondary osteons were significantly decreased (P < 0.05) in the Cd group rats. This fact points to alterations in bone vascularization.

Conclusions

Subchronic peroral exposure to Cd significantly influences femoral weight and histological structure of compact bone in adult male rats. It induces an early stage of osteoporosis and causes reduced bone vascularization. Histomorphometrical changes of primary and secondary osteons allow for the conclusion that the bone mechanical properties could be weakened in the Cd group rats. The current study significantly expands the knowledge on damaging action of Cd on the bone.

Higher sensitivity to cadmium induced cell death of basal forebrain cholinergic neurons: a cholinesterase dependent mechanism

Cadmium is an environmental pollutant, which is a cause of concern because it can be greatly concentrated in the organism causing severe damage to a variety of organs including the nervous system which is one of the most affected. Cadmium has been reported to produce learning and memory dysfunctions and Alzheimer like symptoms, though the mechanism is unknown. On the other hand, cholinergic system in central nervous system (CNS) is implicated on learning and memory regulation, and it has been reported that cadmium can affect cholinergic transmission and it can also induce selective toxicity on cholinergic system at peripheral level, producing cholinergic neurons loss, which may explain cadmium effects on learning and memory processes if produced on central level. The present study is aimed at researching the selective neurotoxicity induced by cadmium on cholinergic system in CNS. For this purpose we evaluated, in basal forebrain region, the cadmium toxic effects on neuronal viability and the cholinergic mechanisms related to it on NS56 cholinergic mourine septal cell line. This study proves that cadmium induces a more pronounced, but not selective, cell death on acetylcholinesterase (AChE) on cholinergic neurons. Moreover, MTT and LDH assays showed a dose dependent decrease of cell viability in NS56 cells. The ACh treatment of SN56 cells did not revert cell viability reduction induced by cadmium, but siRNA transfection against AChE partially reduced it. Our present results provide new understanding of the mechanisms contributing to the harmful effects of cadmium on the function and viability of neurons, and the possible relevance of cadmium in the pathogenesis of neurodegenerative diseases.

Cadmium exposure and incident peripheral arterial disease

BACKGROUND

Cadmium has been associated with peripheral arterial disease (PAD) in cross-sectional studies, but prospective evidence is lacking. Our goal was to evaluate the association of urine cadmium concentrations with incident PAD in a large population-based cohort.

METHODS AND RESULTS

A prospective cohort study was performed with 2864 adult American Indians 45 to 74 years of age from Arizona, Oklahoma, and North and South Dakota who participated in the Strong Heart Study from 1989 to 1991 and were followed through 2 follow-up examination visits in 1993 to 1995 and 1997 to 1999. Participants were free of PAD, defined as an ankle brachial index <0.9 or >1.4 at baseline, and had complete baseline information on urine cadmium, potential confounders, and ankle brachial index determinations in the follow-up examinations. Urine cadmium was measured using inductively coupled plasma mass spectrometry and corrected for urinary dilution by normalization to urine creatinine. Multivariable-adjusted hazard ratios were computed using Cox-proportional hazards models for interval-censored data. A total of 470 cases of incident PAD, defined as an ankle brachial index <0.9 or >1.4, were identified. After adjustment for cardiovascular disease risk factors including smoking status and pack-years, the hazard ratio comparing the 80th to the 20th percentile of urine cadmium concentrations was 1.41 (1.05-1.81). The hazard ratio comparing the highest to the lowest tertile was 1.96 (1.32-2.81). The association persisted after excluding participants with ankle brachial index >1.4 only as well as in subgroups defined by sex and smoking status.

CONCLUSIONS

Urine cadmium, a biomarker of long-term cadmium exposure, was independently associated with incident PAD, providing further support for cadmium as a cardiovascular disease risk factor.

Cadmium and hypertension in exposed workers: A meta-analysis

OBJECTIVES

In the general population, cadmium seems to be responsible for hypertension, atherosclerosis and an increase in acute coronary events. Therefore, the purpose of this meta-analysis was to analyze controlled studies conducted on cadmium and arterial pressure in occupationally-exposed workers.

MATERIALS AND METHODS

After analyzing all the relevant articles found in the literature, 6 publications were selected.

RESULTS

A higher prevalence of hypertension and higher values of systolic and diastolic blood pressure were recorded in the exposed subjects.

CONCLUSIONS

Cadmium in occupationally-exposed individuals appears to induce an increase in systolic and diastolic blood pressure and an increase in the prevalence of hypertension.

Cadmium exposure and incident cardiovascular disease

BACKGROUND

Cadmium is a widespread toxic metal with potential cardiovascular effects, but no studies have evaluated cadmium and incident cardiovascular disease. We evaluated the association of urine cadmium concentration with cardiovascular disease incidence and mortality in a large population-based cohort.

METHODS

We conducted a prospective cohort study of 3348 American Indian adults 45-74 years of age from Arizona, Oklahoma, and North and South Dakota, who participated in the Strong Heart Study in 1989-1991. Urine cadmium was measured using inductively coupled plasma mass spectrometry. Follow-up extended through 31 December 2008.

RESULTS

The geometric mean cadmium level in the study population was 0.94 μg/g (95% confidence interval [CI] = 0.92-0.96). We identified 1084 cardiovascular events, including 400 deaths. After adjustment for sociodemographic and cardiovascular risk factors, the hazard ratios (HRs) (comparing the 80th to the 20th percentile of urine cadmium concentrations) was 1.43 for cardiovascular mortality (95% CI = 1.21-1.70) and 1.34 for coronary heart disease mortality (1.10-1.63). The corresponding HRs for incident cardiovascular disease, coronary heart disease, stroke, and heart failure were 1.24 (1.11-1.38), 1.22 (1.08-1.38), 1.75 (1.17-2.59), and 1.39 (1.01-1.94), respectively. The associations were similar in most study subgroups, including never-smokers.

CONCLUSIONS

Urine cadmium, a biomarker of long-term exposure, was associated with increased cardiovascular mortality and increased incidence of cardiovascular disease. These findings support that cadmium exposure is a cardiovascular risk factor.

NTPDase and 5'-nucleotidase activities from synaptosomes and platelets of rats exposed to cadmium and treated with N-acetylcysteine

The purpose of the present investigation was to evaluate the hydrolysis of adenine nucleotides on synaptosomes and platelets obtained from rats exposed to cadmium (Cd) and treated with N-acetylcysteine (NAC). Rats received Cd (2 mg/kg) and NAC (150 mg/kg) by gavage every other day for 30 days. Animals were divided into four groups (n = 4-6): control/saline, NAC, Cd, and Cd/NAC. The results of this study demonstrated that NTPDase and 5'-nucleotidase activities were increased in the cerebral cortex synaptosomes of Cd-poisoned rats, and NAC co-treatment reversed these activities to the control levels. In relation to hippocampus synaptosomes, no differences on the NTPDase and 5'-nucleotidase activities of Cd-poisoned rats were observed and only the 5'-nucleotidase activity was increased by the administration of NAC per se. In platelets, Cd-intoxicated rats showed a decreased NTPDase activity and no difference in the 5'-nucleotidase activity; NAC co-treatment was inefficient in counteracting this undesirable effect. Our findings reveal that adenine nucleotide hydrolysis in synaptosomes and platelets of rats were altered after Cd exposure leading to a compensatory response in the central nervous system and acting as a modulator of the platelet activity. NAC was able to modulate the purinergic system which is interesting since the regulation of these enzymes could have potential therapeutic importance. Thus, our results reinforce the importance of the study of the ecto-nucleotidases pathway in poisoning conditions and highlight the possibility of using antioxidants such as NAC as adjuvant against toxicological conditions.

Cadmium exposure and all-cause and cardiovascular mortality in the U.S. general population

BACKGROUND

Urine cadmium concentrations were associated with all-cause and cardiovascular mortality in men in the 1988-1994 U.S. National Health and Nutrition Examination Survey (NHANES) population. Since 1988, cadmium exposure has decreased substantially in the United States. The associations between blood and urine cadmium and cardiovascular disease (CVD) mortality at more recent levels of exposure are unknown.

OBJECTIVES

We evaluated the prospective association of blood and urine cadmium concentrations with all-cause and CVD mortality in the 1999-2004 U.S. population.

METHODS

We followed 8,989 participants who were ≥ 20 years of age for an average of 4.8 years. Hazard ratios for mortality end points comparing the 80th to the 20th percentiles of cadmium distributions were estimated using Cox regression.

RESULTS

The multivariable adjusted hazard ratios [95% confidence intervals (CIs)] for blood and urine cadmium were 1.50 (95% CI: 1.07, 2.10) and 1.52 (95% CI: 1.00, 2.29), respectively, for all-cause mortality, 1.69 (95% CI: 1.03, 2.77) and 1.74 (95% CI: 1.07, 2.83) for CVD mortality, 1.98 (95% CI: 1.11, 3.54) and 2.53 (95% CI: 1.54, 4.16) for heart disease mortality, and 1.73 (95% CI: 0.88, 3.40) and 2.09 (95% CI: 1.06, 4.13) for coronary heart disease mortality. The population attributable risks associated with the 80th percentile of the blood (0.80 μg/L) and urine (0.57 μg/g) cadmium distributions were 7.0 and 8.8%, respectively, for all-cause mortality and 7.5 and 9.2%, respectively, for CVD mortality.

CONCLUSIONS

We found strongly suggestive evidence that cadmium, at substantially low levels of exposure, remains an important determinant of all-cause and CVD mortality in a representative sample of U.S. adults. Efforts to further reduce cadmium exposure in the population could contribute to a substantial decrease in CVD disease burden.

Cadmium and peripheral arterial disease: gender differences in the 1999-2004 US National Health and Nutrition Examination Survey

Gender differences in the association of blood and urine cadmium concentrations with peripheral arterial disease (PAD) were evaluated by using data from 6,456 US adults aged ≥40 years who participated in the 1999-2004 National Health and Nutrition Examination Survey. PAD was defined as an ankle-brachial blood pressure index of <0.9 in at least one leg. For men, the adjusted odds ratios for PAD comparing the highest with the lowest quintiles of blood and urine cadmium concentrations were 1.82 (95% confidence interval (CI): 0.82, 4.05) and 4.90 (95% CI: 1.55, 15.54), respectively, with a progressive dose-response relation and no difference by smoking status. For women, the corresponding odds ratios were 1.19 (95% CI: 0.66, 2.16) and 0.56 (95% CI: 0.18, 1.71), but there was evidence of effect modification by smoking: among women ever smokers, there was a positive, progressive dose-response relation; among women never smokers, there was a U-shaped dose-response relation. Higher blood and urine cadmium levels were associated with increased prevalence of PAD, but women never smokers showed a U-shaped relation with increased prevalence of PAD at very low cadmium levels. These findings add to the concern of increased cadmium exposure as a cardiovascular risk factor in the general population.

Correlations of urinary cadmium with hypertension and diabetes in persons living in cadmium-contaminated villages in northwestern Thailand: A population study

Risk for hypertension and diabetes has not been conclusively found to be a result of cadmium exposure. A population-based study was conducted in 2009 to examine the correlations of urinary cadmium, a good biomarker of long-term cadmium exposure, with hypertension and diabetes in persons aged 35 years and older who lived in the 12 cadmium-contaminated rural villages in northwestern Thailand. A total of 5273 persons were interviewed and screened for urinary cadmium, hypertension, and diabetes. The geometric mean level of urinary cadmium for women (2.4+/-2.3 microg/g creatinine) was significantly greater than that for men (2.0+/-2.2 microg/g creatinine). Hypertension was presented in 29.8% of the study population and diabetes was detected in 6.6%. The prevalence of hypertension significantly increased from 25.0% among persons in the lowest tertile of urinary cadmium to 35.0% in the highest tertile. In women, the rate of hypertension significantly increased with increasing urinary cadmium levels in both ever and never smokers, after adjusting for age, alcohol consumption, body mass index, and diabetes. In men, such association was less significantly found in never smokers. The study revealed no significant association between urinary cadmium and diabetes in either gender. Our study supports the hypothesis that environmental exposure to cadmium may increase the risk of hypertension. Risk for diabetes in relation to cadmium exposure remains uncertain in this exposed population.

Chronic exposure to arsenic in tap water reduces acetylcholine-induced relaxation in the aorta and increases oxidative stress in female rats

The aim of this work is to determine whether consuming tap water containing arsenic (20 microg/L) alters oxidative stress levels in female rats and changes vascular response. Whereas nitric oxide produces complete relaxation, arsenic (7 months of exposure) impairs the acetylcholine-induced endothelial relaxation in the rat aorta compared with control rats. Arsenic exposure results in a marked elevation in reactive oxygen species in blood, and delta-aminolevulinic acid dehydratase activity, which is a sensitive biomarker for arsenic toxicity and oxidative stress, is significantly decreased in erythrocytes from 7-month-old rats. Diastolic blood pressure increases significantly in 7-month-old arsenic-treated versus control rats. The percentage of change in peripheral resistance increases. The results indicate that chronic environmental exposure to low levels of arsenic alters the release of vasoactive substances, causes changes in oxidative stress, and increases blood pressure in female rats.

Cadmium attenuates bradykinin-driven nitric oxide production by interplaying with the localization pattern of endothelial nitric oxide synthase

Cadmium, a ubiquitous heavy metal, interferes with endothelial functions and angiogenesis. Bradykinin is a Ca-mobilizing soluble peptide that acts via nitric oxide to promote vasodilation and capillary permeability. The objective of the present study was to explore the Cd implications in bradykinin-dependent endothelial functions. An egg yolk angiogenesis model was employed to evaluate the effect of Cd on bradykinin-induced angiogenesis. The results demonstrate that 100 nmol/L Cd attenuated bradykinin-dependent angiogenesis. The results of the in vitro wound healing and tube formation assays by using EAhy 926, a transformed endothelial cell line, suggest that Cd blocked bradykinin-mediated endothelial migration and tube formation by 38% and 67%, respectively, while nitric oxide supplementation could reverse the effect of Cd on bradykinin-induced endothelial migration by 94%. The detection of nitric oxide by using a DAF-2DA fluorescent probe, Griess assay, and ultrasensitive electrode suggests that Cd blocked bradykinin-induced nitric oxide production. Fluorescence imaging of eNOS-GFP transfected endothelial cells, immunofluorescence, and Western blot studies of Cd and bradykinin-treated cells show that Cd interfered with the localization pattern of eNOS, which possibly attenuates nitric oxide production in part. Additionally, Ca imaging of Cd- and bradykinin-treated cells suggests that Cd blocked bradykinin-dependent Ca influx into the cells, thus partially blocking Ca-dependent nitric oxide production in endothelial cells. The results of this study conclude that Cd blunted the effect of bradykinin by interfering with the Ca-associated NOS activity specifically by impeding subcellular trafficking of eNOS.

Impairment of endothelium-dependent vasorelaxation in cadmium-hypertensive rats

Abnormalities in the production and/or release of relaxing factors from the endothelium have been implicated in the development of hypertension in several animal models. Endothelium-dependent relaxation has been reported to be impaired in thoracic aorta in experimentally induced and genetically hypertensive rats. Present study has extented these observations to thoracic aorta of cadmium-hypertensive rats. The possible role of alterations in oxidant status was also studied. Hypertension was induced by the intraperitoneal administration of 1 mg/kg/day cadmium for 15 days. Mechanical responses produced by acetylcholine (ACh, 10— 9—10—4 M) and sodium nitroprusside (SNP, 10—10—10— 5 M) were studied on phenylephrine-precontracted thoracic aorta rings from control and cadmium-hypertensive rats. Serum nitric oxide (NO) and aortic malondialdehyde (MDA) levels were measured. ACh-induced relaxation was attenuated in aorta from cadmium-hypertensive rats, whereas relaxation responses to SNP did not differ significantly between the groups. Exposure of aortic rings to NG-nitro-L-arginine methyl ester (L-NAME, 10 —4 M) resulted in a significantly greater inhibition of relaxation response to ACh in aortic rings of cadmium-hypertensive rats as compared with control rats. Incubation with L-arginine (L-Arg, 10 —3 M) caused a similar reversal of the inhibition of ACh-induced relaxation by L-NAME in both groups. Serum NO levels were decreased and aortic MDA levels were increased in cadmium-treated rats as compared with control rats. However, the differences between the groups did not reach a statistical significance. These findings suggested that the reduction in endothelium-dependent relaxation may play a role in cadmium-induced hypertension as it was in many other hypertension models.

Dietary Silica Modifies the Characteristics of Endothelial Dilation in Rat Aorta

Considering the importance of nitric oxide generation in the regulation of vessel tone, reduced endothelial nitric oxide synthase (eNOS) expression in alveolar macrophages exposed to short-term silica (Si) suggests the possibility of Si-induced changes in endothelial functions. In this experimental study, the functional changes of the endothelial cells were investigated in the aortic rings of rats subjected to 50 mg Si/kg body weight in their drinking water for 8 days. Norepinephrine elicited contractility and dilation response to acetylcholine (ACh) was significantly high in the aortic rings of Si-treated group. Alteration in receptor-independent endothelial response to A23187 in the aortic rings of Si-exposed rats was less obvious, but sodium nitroprusside (SNP)-elicited dilation was reduced significantly. A23187-induced relaxation was fully eliminated with N-nitro-L-arginine methyl ester (L-NAME) pretreatment, whereas 19.24 +/- 4.36% of ACh response was L-NAME resistant and eliminated with 10-5 M tetraethylammonium (TEA). Despite a significant reduction in the share of NO, the contribution of indomethacine (IND)-sensitive relaxation to ACh response remained unchanged in Si group. As a result, our findings demonstrated that Si both modifies the characteristics of endothelial relaxants and attenuates smooth muscle cell responsiveness to NO. Si-induced reduced NO association with elevated endothelium-derived hyperpolarizing factor (EDHF) in response to ACh, together with reduced NO sensitization, might have clinical importance in cardiovascular pathology.

The vascular system as a target of metal toxicity

Vascular system function involves complex interactions among the vascular endothelium, smooth muscle, the immune system, and the nervous system. The toxic metals cadmium (Cd), arsenic (As), and lead (Pb) can target the vascular system in a variety of ways, ranging from hemorrhagic injury to subtle pathogenic remodeling and metabolic changes. Acute Cd exposure results in hemorrhagic injury to the testis, although some strains of animals are resistant to this effect. A comparison of Cd-sensitive with Cd-resistant mouse strains showed that expression of the Slc39a8 gene, encoding the ZIP8 transporter, in the testis vasculature endothelium is responsible for this difference. Endogenously, ZIP8 is a Mn(2+)/HCO(3)(-)symporter that may also contribute to Cd damage in the kidney. Chronic Cd exposure is associated with various cardiovascular disorders such as hypertension and cardiomyopathy and it is reported to have both carcinogenic and anticarcinogenic activities. At noncytotoxic concentrations of 10-100nM, Cd can inhibit chemotaxis and tube formation of vascular endothelial cells. These angiostatic effects may be mediated through disruption of vascular endothelial cadherin, a Ca(2+)-dependent cell adhesion molecule. With regard to As, ingestion of water containing disease-promoting concentrations of As promotes capillarization of the liver sinusoidal endothelium. Because capillarization is a hallmark precursor for liver fibrosis and contributes to an imbalance of lipid metabolism, this As effect on hepatic endothelial cells may be a pathogenic mechanism underlying As-related vascular diseases. With regard to Pb, perinatal exposure may cause sustained elevations in adult blood pressure, and genetically susceptible animals may show enhanced sensitivity to this effect. Taken together, these data indicate that the vascular system is a critical target of metal toxicity and that actions of metals on the vascular system may play important roles in mediating the pathophysiologic effects of metals in specific target organs.

Cadmium exposure and hypertension in the 1999-2004 National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION

Cadmium induces hypertension in animal models. Epidemiologic studies of cadmium exposure and hypertension, however, have been inconsistent.

OBJECTIVE

We aimed to investigate the association of blood and urine cadmium with blood pressure levels and with the prevalence of hypertension in U.S. adults who participated in the 1999-2004 National Health and Nutrition Examination Survey (NHANES).

METHODS

We studied participants > or = 20 years of age with determinations of cadmium in blood (n = 10,991) and urine (n = 3,496). Blood and urine cadmium were measured by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Systolic and diastolic blood pressure levels were measured using a standardized protocol.

RESULTS

The geometric means of blood and urine cadmium were 3.77 nmol/L and 2.46 nmol/L, respectively. After multivariable adjustment, the average differences in systolic and diastolic blood pressure comparing participants in the 90th vs. 10th percentile of the blood cadmium distribution were 1.36 mmHg [95% confidence interval (CI), -0.28 to 3.00] and 1.68 mmHg (95% CI, 0.57-2.78), respectively. The corresponding differences were 2.35 mmHg and 3.27 mmHg among never smokers, 1.69 mmHg and 1.55 mmHg among former smokers, and 0.02 mmHg and 0.69 mmHg among current smokers. No association was observed for urine cadmium with blood pressure levels, or for blood and urine cadmium with the prevalence of hypertension.

CONCLUSIONS

Cadmium levels in blood, but not in urine, were associated with a modest elevation in blood pressure levels. The association was stronger among never smokers, intermediate among former smokers, and small or null among current smokers. Our findings add to the concern of renal and cardiovascular cadmium toxicity at chronic low levels of exposure in the general population.

Effects of Acute and Chronic Cadmium Administration on the Vascular Reactivity of Rat Aorta

The effect of acute and chronic cadmium (Cd) administration on the vascular function of the rat aorta was studied. The rats were randomly divided into four main groups (A: saline controls under chronic administration, B: Cd-treated rats under chronic administration, C: saline controls under acute administration, D: Cd-treated rats under acute administration). After their sacrifice, the aortic rings were divided into rings with endothelium (E+) and without (E-), and suspended in an isolated organ bath with Krebs - Henseleit buffer. Maximal tension (T max, in g) was measured in response to potassium chloride (KCl) and phenylephrine (PE) in all aortic rings. Relaxation response to acetylcholine (ACh) administration was expressed as percent of maximal tension induced by PE. Chronic administration: A statistically significant increase of the contraction was observed between groups B (i.m. Cd 0.5 mg/kg for 120 days) and A (i.m. 0.9% NaCl for 120 days) in response to KCl (20-60 mM) and the T max as well (in both the E+ and the E- subgroups). No statistically significant difference was observed in response to PE and ACh exposure. Acute administration: A statistically significant increase was observed between group D(E+) (i.m. Cd 2 mg/kg, 8 h before sacrifice) and group C(E+) (i.m. 0.9% NaCl, 8 h before sacrifice) in response to 10-30 mM of KCl, and a significant decrease between D(E-) and C(E-) in response to 10(-7)-10(-6) M of PE, though T (max) was increased between D(E-) and C(E-) with PE exposure. The contractile response levels of the E+ aortic rings to PE and ACh showed no statistically significant difference.

The vascular endothelium as a target of cadmium toxicity

Cadmium (Cd) is an important industrial and environmental pollutant that can produce a wide variety of adverse effects in humans and animals. A growing volume of evidence indicates that the vascular endothelium may be one of the primary targets of Cd toxicity in vivo. Studies over the past 20 years have shown that Cd, at relatively low, sublethal concentrations, can target vascular endothelial cells at a variety of molecular levels, including cell adhesion molecules, metal ion transporters and protein kinase signaling pathways. The purpose of this review is to summarize the results of these recent studies and to discuss the implications of these findings with regard to the mechanisms of Cd toxicity in specific organs including the lung, liver, kidney, testis and heart. In addition the possible roles of the vascular endothelium in mediating the tumor promoting and anticarcinogenic effects of Cd are discussed.

Evaluation of the effects of cadmium on rat liver

Cadmium is one of the most toxic pollutants in environment. Cadmium accumulation in blood affects the renal cortex and causes renal failure. In this study, we aimed to evaluate the effects of cadmium on rat liver tissue. Eighteen male albino rats aged ten weeks old were used in the study. 15 ppm of cadmium was administered to rats via consumption water daily. At the end of the 30th study day, the animals were killed under ether anesthesia. After the liver tissue samples were taken, histopathological and biochemical examinations were performed. Histopathologic changes have included vacuolar and granular degenerations in hepatocytes, heterochromatic nucleuses and sinusoidal and portal widenings. Central vein diameters were normal in cadmium exposed group. Whereas, there was statistically significant difference between two groups by means of sinusoidal (p< 0.001) and portal triad diameters (p< 0.01). Malondialdehyde (MDA) is an indicator of lipid peroxidation. In this study, MDA was used as a marker of oxidative stress-induced liver impairment in cadmium exposed rats. Superoxide dismutase (SOD) and catalase (CAT) activities were also measured to evaluate the changes in antioxidative system in liver tissues. Current findings showed that MDA levels were increased and SOD and CAT activities were decreased in cadmium exposed group compared to control group. The difference between two groups was statistically significant (pvalues: MDA,p< 0.01; CAT,p< 0.01 and SOD,p< 0.05). In conclusion, these findings suggest the role of oxidative mechanisms in cadmium-induced liver tissue damage.