Interaction of cadmium with atrial natriuretic peptide receptors: implications for toxicity

The general external exposome and the development or progression of chronic kidney disease: A systematic review and meta-analyses

The impact of environmental risk factors on chronic kidney disease (CKD) remains unclear. This systematic review aims to provide an overview of the literature on the association between the general external exposome and CKD development or progression. We searched MEDLINE and EMBASE for case-control or cohort studies, that investigated the association of the general external exposome with a change in eGFR or albuminuria, diagnosis or progression of CKD, or CKD-related mortality. The risk of bias of included studies was assessed using the Newcastle-Ottawa Scale. Summary effect estimates were calculated using random-effects meta-analyses. Most of the 66 included studies focused on air pollution (n = 33), e.g. particulate matter (PM) and nitric oxides (NOx), and heavy metals (n = 21) e.g. lead and cadmium. Few studies investigated chemicals (n = 7) or built environmental factors (n = 5). No articles on other environment factors such as noise, food supply, or urbanization were found. PM2.5 exposure was associated with an increased CKD and end-stage kidney disease incidence, but not with CKD-related mortality. There was mixed evidence regarding the association of NO2 and PM10 on CKD incidence. Exposure to heavy metals might be associated with an increased risk of adverse kidney outcomes, however, evidence was inconsistent. Studies on effects of chemicals or built environment on kidney outcomes were inconclusive. In conclusion, prolonged exposure to PM2.5 is associated with an increased risk of CKD incidence and progression to kidney failure. Current studies predominantly investigate the exposure to air pollution and heavy metals, whereas chemicals and the built environment remains understudied. Substantial heterogeneity and mixed evidence were found across studies. Therefore, long-term high-quality studies are needed to elucidate the impact of exposure to chemicals or other (built) environmental factors and CKD.

Molecular Mechanisms of Cellular Injury and Role of Toxic Heavy Metals in Chronic Kidney Disease

Chronic kidney disease (CKD) is a progressive disease that affects millions of adults every year. Major risk factors include diabetes, hypertension, and obesity, which affect millions of adults worldwide. CKD is characterized by cellular injury followed by permanent loss of functional nephrons. As injured cells die and nephrons become sclerotic, remaining healthy nephrons attempt to compensate by undergoing various structural, molecular, and functional changes. While these changes are designed to maintain appropriate renal function, they may lead to additional cellular injury and progression of disease. As CKD progresses and filtration decreases, the ability to eliminate metabolic wastes and environmental toxicants declines. The inability to eliminate environmental toxicants such as arsenic, cadmium, and mercury may contribute to cellular injury and enhance the progression of CKD. The present review describes major molecular alterations that contribute to the pathogenesis of CKD and the effects of arsenic, cadmium, and mercury on the progression of CKD.

The effects of short-term nifedipine treatment on responsiveness of aortic rings of cadmium-hypertensive rats

The effects of short-term antihypertensive treatment with nifedipine on blood pressure and vascular responsiveness were studied in cadmium-hypertensive and normotensive control rats. Cadmium administration caused a significant increase in mean arterial blood pressure. Endothelin-1, noradrenaline and angiotensin II produced concentration dependent contractions of aortic rings that attained a lower maximal contraction in cadmium-hypertensive rats. Responses of aortic rings to KCl did not show a significant difference between the groups. Nifedipine administered simultaneously with cadmium inhibited the induction of hypertension. Nifedipine treatment for 5 days significantly reduced the blood pressure in cadmium-hypertensive and normotensive rats. Neither inhibition of hypertension nor normalization of blood pressure in cadmium-hypertensive rats caused an alteration in contractile responses of aortic rings to vasoconstrictors which suggested that development of decreased vascular reactivity and of hypertension occurs simultaneously in cadmium-hypertensive rats but the role of decreased vascular reactivity in maintenance of hypertension is questionable in cadmium-hypertension.

Cadmium induced lipid peroxidation in kidney function

Since the kidney is the main target organ for many metals including cadmium, the generation of the products of lipid peroxidation due to accumulation of these toxic metals in the kidney may have importance in the mechanism of their nephrotoxicity. In order to test this hypothesis, we carried out an experimental study in rats. The functions and the levels of tiobarbituric acid reactive substances (TBARS) of the kidney were investigated in animals receiving 15 micrograms/ml aqueous Cd solution for 30 days. Due to cadmium accumulation in kidney cortex, the ratio of Cd/Zn increased significantly and this increase was associated with elevated TBARS in both renal cortex and medulla. The content of TBARS in renal cortex rose from 211.6 +/- 64.2 to 303.4 +/- 46.4 nmol/g protein (p<0.01) and GFR decreased to 390.5 +/- 109.4 from 1008.7 +/- 4.8 microliters/min (p<0.01) in cadmium exposed animals. Daily coadministration of selenium, vitamins A, C, E did not reverse the adverse effect of cadmium on kidney function, despite the significant decrease in cortex TBARS levels (p<0.01). In conclusion, these data suggest to us that lipid peroxidation assessed by TBA test may not be the only mechanism in cadmium induced nephrotoxicity.