Effect of prolonged incubation with copper on endothelium-dependent relaxation in rat isolated aorta

The Effect of an Elevated Dietary Copper Level on the Vascular Contractility and Oxidative Stress in Middle-Aged Rats

Copper (Cu), being an essential mineral, plays a crucial role in maintaining physiological homeostasis across multiple bodily systems, notably the cardiovascular system. However, an increased Cu level in the body may cause blood vessel dysfunction and oxidative stress, which is unfavorable for the cardiovascular system. Middle-aged (7-8 months old) male Wistar rats (n/group = 12) received a diet supplemented with 6.45 mg Cu/kg (100% of the recommended daily dietary quantity of copper) for 8 weeks (Group A). The experimental group received 12.9 mg Cu/kg of diet (200%-Group B). An ex vivo study revealed that supplementation with 200% Cu decreased the contraction of isolated aortic rings to noradrenaline (0.7-fold) through FP receptor modulation. Vasodilation to sodium nitroprusside (1.10-fold) and acetylcholine (1.13-fold) was potentiated due to the increased net effect of prostacyclin derived from cyclooxygenase-1. Nitric oxide (NO, 2.08-fold), superoxide anion (O2•-, 1.5-fold), and hydrogen peroxide (H2O2, 2.33-fold) measured in the aortic rings increased. Blood serum antioxidant status (TAS, 1.6-fold), Cu (1.2-fold), Zn (1.1-fold), and the Cu/Zn ratio (1.4-fold) increased. An increase in Cu (1.12-fold) and the Cu/Zn ratio (1.09-fold) was also seen in the rats' livers. Meanwhile, cyclooxygenase-1 (0.7-fold), cyclooxygenase-2 (0.4-fold) and glyceraldehyde 3-phosphate dehydrogenase (0.5-fold) decreased. Moreover, a negative correlation between Cu and Zn was found (r = -0.80) in rat serum. Supplementation with 200% Cu did not modify the isolated heart functioning. No significant difference was found in the body weight, fat/lean body ratio, and organ weight for either the heart or liver, spleen, kidney, and brain. Neither Fe nor Se, the Cu/Se ratio, the Se/Zn ratio (in serum and liver), heme oxygenase-1 (HO-1), endothelial nitric oxide synthase (eNOS), or intercellular adhesion molecule-1 (iCAM-1) (in serum) were modified. Supplementation with 200% of Cu potentiated pro-oxidant status and modified vascular contractility in middle-aged rats.

Carcinogenic and non-carcinogenic human health risk assessments of heavy metals contamination in drinking water supplies in Iran: a systematic review

The contamination of water due to heavy metals (HMs) is a big concern for humankind; particularly in developing countries. This research is a systematic review, conducted by searching google scholar, Web of Science, Science Direct, PubMed, Springer, and Scopus databases for related published papers from 2010 to July 2021, resulting in including 40 articles. Among the analyzed HMs in the presented review, the average content of Cr, Pb, Ba, Al, As, Zn, and Cd exceeded the permissible limits suggested by the World Health Organization (WHO) and 1,053 Iranian standards. Also, the rank order of Hazard Quotient (HQ) of HMs was defined as Cd>As>Cr>Pb>Li for children which means Cd has the highest non-carcinogenic risk and Li has the least. This verifies to the current order As>Cr>Pb>Fe=Zn=Cu>Cd for adults. The corresponded values of HQ and Hazard Index (HI) in most cities and villages were investigated and the results indicated a lower than 1 value, which means consumers are not at non-carcinogenic risk (HQ). Carcinogenic risk (CR) of As in the adult and children consumers in most of the samples (58.82% of samples for both groups) were investigated too, and it was more than>1.00E-04 value, which determines that consumers are at significant CR.

Different types of cell death in diabetic endothelial dysfunction

Diabetes mellitus is a metabolic disease caused by disorders of insulin secretion and utilization. Long-term hyperglycemia, insulin resistance, and disorders of glucose and lipid metabolism cause vascular endothelial cell damage. Endothelial dysfunction is a key feature of diabetic vascular complications such as diabetic nephropathy, retinopathy, neuropathy, and atherosclerosis. Importantly, cell death is thought to be a key factor contributing to vascular endothelial injury. Morphologically, cell death can be divided into three forms: type I apoptosis, type II autophagy, and type III necrosis. According to the difference in function, cell death can be divided into accidental cell death (ACD) and regulated cell death (RCD). RCD is a controlled process involving numerous proteins and precise signaling cascades. Multiple subroutines covered by RCD may be involved in diabetic endothelial dysfunction, including apoptosis, autophagy, necroptosis, pyroptosis, entosis, ferroptosis, ferroautophagy, parthanatos, netotic cell death, lysosome-dependent cell death, alkaliptosis, oxeiptosis, cuproptosis, and PANoptosis. This article briefly reviews the mechanism and significance of cell death associated with diabetic endothelial dysfunction, which will help deepen the understanding of diabetic endothelial cell death and provide new therapeutic ideas.

Copper and Zinc Particles as Regulators of Cardiovascular System Function-A Review

Copper and zinc are micronutrients that play a crucial role in many cellular pathways, act as cofactors in enzymatic systems, and hence, modulate enzyme activity. The regulation of these elements in homeostasis is precisely controlled by various mechanisms. Superoxide dismutase (SOD) is an enzyme requiring both copper and zinc for proper functioning. Additionally, there is an interaction between the concentrations of copper and zinc. Dietary ingestion of large amounts of zinc augments intestinal absorption of this trace element, resulting in copper deficiency secondary to zinc excess. The presence of an overabundance of copper and zinc has a detrimental impact on the cardiovascular system; however, the impact on vascular contractility varies. Copper plays a role in the modulation of vascular remodeling in the cardiac tissue, and the phenomenon of cuproptosis has been linked to the pathogenesis of coronary artery disease. The presence of copper has an observable effect on the vasorelaxation mediated by nitric oxide. The maintenance of proper levels of zinc within an organism influences SOD and is essential in the pathogenesis of myocardial ischemia/reperfusion injury. Recently, the effects of metal nanoparticles have been investigated due to their unique characteristics. On the other hand, dietary introduction of metal nanoparticles may result in vascular dysfunction, oxidative stress, and cellular DNA damage. Copper and zinc intake affect cardiovascular function, but more research is needed.

Exploring the Link Between the Serum/Blood Levels of Heavy Metals (Pb, As, Cd, and Cu) and 2 Novel Biomarkers of Cardiovascular Stress (Growth Differentiation Factor 15 and Soluble Suppression of Tumorigenicity 2) in Copper Smelter Workers

OBJECTIVE

Studying the association between the occupational exposure to Pb, As, Cd, and Cu with the serum levels of 2 novel biomarkers of cardiovascular stress; growth differentiation factor 15 and soluble suppression of tumorigenicity 2, in some Egyptian Cu smelter workers.

METHODS

Forty-one exposed workers and 41 administrative controls were clinically evaluated. Serum/blood levels of heavy metals and biomarkers were measured for both groups.

RESULTS

The smelter workers showed significantly elevated levels of heavy metals and biomarkers compared with controls. The elevated serum levels of both biomarkers were significantly and positively correlated with each other, the levels of heavy metals, and the duration of employment of the exposed workers.

CONCLUSIONS

There was a significant association between the levels of heavy metals and both biomarkers among the smelter workers. Further prospective studies should be performed.

Carcinogenic and Non-carcinogenic Risk Assessment of Heavy Metals in Groundwater Wells in Neyshabur Plain, Iran

The present work reports the As, Cr, Cu, Pb, Zn, and Fe concentrations of drinking water samples in Neyshabur Plain, Iran. This study aimed also to ascertain the potential consumers' health risk of heavy metal intake. Heavy metal concentrations were analyzed by inductively coupled plasma optical emission spectrometry. The highest and lowest average values in the analyzed water samples were observed for Fe (9.78 ± 5.61 μg/L) and As (1.30 ± 2.99 μg/L), respectively. These values were well below the limits recommended by the World Health Organization and the Iranian national standard. Heavy metal pollution index and heavy metal evaluation index were used to evaluate drinking water quality. The risk index was calculated by chronic daily intake and hazard quotient according to the United States Environmental Protection Agency approach. Heavy metal pollution index in all the samples was less than 100, indicating that it is a low-level heavy metal. The total risk of all heavy metals in the urban environment varied from 40.164 × 10^-7 to 174.8 × 10^-7. In this research, the maximum average of risk belonged to lead and copper with the respective values of 60.10 × 10^-7and 33.99 × 10^-7 from the selected wells. However, considering the toxic effect of some elements, including Pb and As, in the chronic exposure of consumers, we suggest a continuous evaluation and monitoring of drinking water resources.

Behind the Link between Copper and Angiogenesis: Established Mechanisms and an Overview on the Role of Vascular Copper Transport Systems

Angiogenesis critically sustains the progression of both physiological and pathological processes. Copper behaves as an obligatory co-factor throughout the angiogenic signalling cascades, so much so that a deficiency causes neovascularization to abate. Moreover, the progress of several angiogenic pathologies (e.g. diabetes, cardiac hypertrophy and ischaemia) can be tracked by measuring serum copper levels, which are being increasingly investigated as a useful prognostic marker. Accordingly, the therapeutic modulation of body copper has been proven effective in rescuing the pathological angiogenic dysfunctions underlying several disease states. Vascular copper transport systems profoundly influence the activation and execution of angiogenesis, acting as multi-functional regulators of apparently discrete pro-angiogenic pathways. This review concerns the complex relationship among copper-dependent angiogenic factors, copper transporters and common pathological conditions, with an unusual accent on the multi-faceted involvement of the proteins handling vascular copper. Functions regulated by the major copper transport proteins (CTR1 importer, ATP7A efflux pump and metallo-chaperones) include the modulation of endothelial migration and vascular superoxide, known to activate angiogenesis within a narrow concentration range. The potential contribution of prion protein, a controversial regulator of copper homeostasis, is discussed, even though its angiogenic involvement seems to be mainly associated with the modulation of endothelial motility and permeability.

Short-term type 1 diabetes alters the mechanism of endothelium-dependent relaxation in the rat carotid artery

The aim of the present study was to examine the effect of an early stage of streptozotocin-induced diabetes on the mechanism(s) of endothelium-dependent relaxation. Diabetes was induced by a single injection of streptozotocin (48 mg/kg iv), and the ACh-induced relaxation of rat carotid arteries was examined 6 wk later. A diabetes-induced increase in superoxide levels, determined by L-012-induced chemiluminescence, from carotid arteries was associated with endothelial nitric oxide (NO) synthase (eNOS) uncoupling and increased catalytic subunit of NADPH oxidase expression. The sensitivity and maximum response to ACh were similar in normal and diabetic rats despite a decrease in NO release detected by 4-amino-5-methylamino-2′,7′-difluorofluorescein. In normal rats, N-nitro-l-arginine (100 μM) plus 1 H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (10 μM), to inhibit NOS and soluble guanylate cyclase (sGC), respectively, abolished ACh-induced relaxation, whereas in diabetic rats, the maximum relaxation to ACh was attenuated (maximum relaxation: 25 ± 5%), but not abolished, by that treatment. The remaining ACh-induced relaxation was abolished by NO scavengers, cupric chloride (to degrade nitrosothiols), or blockers of endothelial K+ channels. Western blot analysis of the carotid arteries indicated that diabetes significantly increased the expression of eNOS but decreased the proportion of eNOS expressed as the dimer. These findings demonstrate that in early diabetes, ACh-induced relaxation is maintained but is resistant to NOS inhibition. In early diabetes, nitrosothiol-mediated opening of K+ channels may act in conjunction with NO stimulation of sGC to maintain endothelium-dependent relaxation despite the increase in vascular superoxide levels.

Anti-oxidant activity of spermine and spermidine re-evaluated with oxidizing systems involving iron and copper ions

This study was designed to investigate the direction of redox reactions of spermine and spermidine in the presence of iron and copper. The redox activity of spermine and spermidine was assessed using a variety of methods, including their ability to: (1) reduce Fe(3+) to Fe(2+) ions; (2) protect deoxyribose from oxidation by Fe(2+)-ethylene diaminetetraacetic acid, Fe(3+)-ethylene diaminetetraacetic acid systems with and without H(2)O(2); (3) protect DNA from damage caused by Cu(2+)-H(2)O(2), and Fe(2+)-H(2)O(2) with and without ascorbic acid; (4) inhibit H(2)O(2)-peroxidase-induced luminol dependent chemiluminescence; (5) scavenge diphenyl-picryl-hydrazyl radical. Spermine and spermidine at concentration 1mM reduced 1.8+/-0.3 and 2.5+/-0.1 nmol of Fe(3+) ions during 20 min incubation. Both polyamines enhanced deoxyribose oxidation. The highest enhancement of 7.6-fold in deoxyribose degradation was found for combination of spermine with Fe(3+)-ethylene diaminetetraacetic acid. An 10mM spermine and spermidine decreased CuSO(4)-H(2)O(2)-ascorbic acid- and FeSO(4)-H(2)O(2)-ascorbic-induced DNA damage by 73+/-6, 69+/-4% and 90+/-5, 53+/-4%, respectively. They did not protect DNA from CuSO(4)-H(2)O(2) and FeSO(4)-H(2)O(2). Spermine apparently increased the CuSO(4)-H(2)O(2)-dependent injury to DNA. Polyamines attenuated H(2)O(2)-peroxidase-induced luminol dependent chemiluminescence. Total light emission from specimens containing 10mM spermine or spermidine was attenuated by 85.3+/-1.5 and 87+/-3.6%. During 20 min incubation 1mM spermine or spermidine decomposed 8.1+/-1.4 and 9.2+/-1.8% of diphenyl-picryl-hydrazyl radical. These results demonstrate that polyamines of well known anti-oxidant properties may act as pro-oxidants and enhance oxidative damage to DNA components in the presence of free iron ions and H(2)O(2).

Vascular and renal effects of vasopeptidase inhibition and angiotensin-converting enzyme blockade in spontaneously diabetic Goto-Kakizaki rats

BACKGROUND

The renin-angiotensin system plays an important role in the pathogenesis of diabetes-induced vascular and renal complications. Vasopeptidase inhibitors simultaneously inhibit angiotensin-converting enzyme (ACE) and neutral endopeptidase.

OBJECTIVE

To compare the effectiveness of vasopeptidase inhibition and ACE inhibition in preventing hypertension, endothelial dysfunction and diabetic nephropathy in spontaneously diabetic Goto-Kakizaki (GK) rats.

METHODS

Eight-week-old GK rats received omapatrilat (40 mg/kg) or enalapril (30 mg/kg) for 12 weeks, either during a normal-sodium or high-sodium diet (7% w/w). Blood pressure, arterial functions and renal morphology were determined.

RESULTS

Blood pressure and albuminuria were increased in GK rats compared to non-diabetic Wistar controls. Endothelium-dependent vascular relaxation in response to acetylcholine (ACh) and endothelium-independent vascular relaxation in response to sodium nitroprusside (SNP) were impaired in GK rats. Experiments with N-nitro-L-arginine methyl ester (L-NAME), diclofenac, and L-NAME + diclofenac suggested that cyclooxygenase and endothelium-derived hyperpolarizing factor components of endothelium-dependent vascular relaxation were also impaired. A high-sodium diet aggravated hypertension and diabetes-induced vascular and renal complications. Omapatrilat and enalapril normalized blood pressure and albuminuria during the normal-sodium diet, and effectively ameliorated diabetes-induced renal complications also during the high-sodium diet. However, omapatrilat improved endothelium-dependent relaxation to ACh to a greater extent (85 +/- 5%) than enalapril (68 +/- 6%, P < 0.05). Diclofenac pre-incubation eliminated this difference between omapatrilat and enalapril in ACh-induced vascular relaxation, suggesting that it was mediated, at least in part, via the cyclooxygenase pathway.

CONCLUSIONS

Despite comparable blood pressure-lowering and renoprotective properties, omapatrilat may be more effective in preventing vascular dysfunction during diabetes compared to enalapril in GK rats.

Low micromolar concentrations of copper augment the impairment of endothelium-dependent relaxation of aortae from diabetic rabbits

Both diabetes mellitus (DM) and elevated plasma copper concentrations are risk factors for cardiovascular disease (CVD). DM is associated with impaired endothelial nitric oxide (NO) and with excess superoxide (O2*-) formation. Copper is also elevated in DM and is also associated with the generation of O2*-. To explore possible interactions between DM and copper, the effect of exogenous copper (CuCl2) on endothelium-dependent relaxation and cyclic guanosine monophosphate (GMP) formation was investigated in aortae from diabetic rabbits. Rabbits were rendered diabetic by intravenous injection of alloxan. Six months after induction of DM, the aortae were excised, cut into rings, and mounted in an organ bath for isometric measurement of acetylcholine (Ach)-evoked relaxation in rings precontracted with phenylephrine (PE). In parallel studies, cyclic (c)GMP formation by aortic rings following stimulation with Ach, calcium ionophore A23187 (A23187) and sodium nitroprusside (SNP) was assessed using radioimmunoassay. The effect of copper on these parameters was then studied using the same methods. Ach-evoked relaxation and Ach- and A23187-evoked cGMP formation were significantly impaired in aortae from diabetic rabbits compared to controls, effects that were reversed with superoxide dismutase (SOD) and catalase (CAT). In contrast, there were no significant differences in SNP-stimulated relaxation or cGMP formation in aortae from diabetic rabbits compared to controls. Copper (1 to 10 micromol/L) promoted a further significant inhibition of Ach-stimulated relaxation in aortae from diabetic but not control rabbits. This reduction by copper was again reversed by SOD and CAT. We conclude that copper augments the reduction of NO bioavailability, which is already impaired in aortae from diabetic rabbits due to excess production of O2*- and H2O2. These results indicate that patients with DM may be susceptible to copper-mediated vasculopathy at much lower concentrations than those that promote vasculopathy in nondiabetic patients.

Reciprocal regulation and integration of signaling by intracellular calcium and cyclic GMP

Calcium and guanosine-3',5'-cyclic monophosphate (cGMP) are second messenger molecules that regulate opposing physiological functions, reflected in the reciprocal regulation of their intracellular concentrations, in many systems. Indeed, cGMP and Ca2+ constitute discrete points of integration between multiple cell signaling cascades in both convergent and parallel pathways. This chapter describes the molecular mechanisms regulating intracellular Ca2+ and cGMP, and their integration in specific cellular responses.

Copper induces type II nitric oxide synthase in vivo

Intravenous administration of copper (up to a final concentration of ca. 35 micromol/l in the plasma) led to a progressive, dramatic fall of mean arterial pressure in rats. Copper-induced pressure changes were comparable to those elicited by 2 mg/kg LPS, and were greatly prevented by previous infusion of the inducible NOS (NOS-II) inhibitors aminoguanidine or l-N(6)-(L-imino-ethyl)lysine. RT-PCR analysis showed a significant transcriptional induction of NOS-II in a number of tissues, including aorta, liver, and lungs. Immunohistochemistry revealed that NOS-II was massively synthesized in these tissues upon copper or LPS treatment. The protein was active, as revealed by enzymatic assays on lung homogenates and by the large increase of nitrite/nitrate levels in the plasma. Copper-challenged rats displayed elevated plasma levels of TNFalpha. Extensive formation of nitrotyrosines, indicative of peroxynitrite production, was accompanied by marked morphological changes in examined tissues. Our results clearly show that copper can act as a proinflammatory agent through activation of the nitric oxide pathway, leading to the same pathological frame induced by bacterial lipopolysaccharide.