LLC-PK1 cells as a model for renal toxicity caused by arsine exposure

Role of glutaredoxin-mediated protein S-glutathionylation in cellular nitroglycerin tolerance

We hypothesize that nitroglycerin (NTG) causes direct oxidation of multiple cellular sulfhydryl (SH) proteins and that manipulation of SH redox status affects NTG tolerance. In LLC-PK1 cells, we found that nitrate tolerance, as indicated by cGMP accumulation toward NTG, was accompanied by increased protein [(35)S]cysteine incorporation, significant S-glutathionylation of multiple proteins, and decreased metabolic activity of several SH-sensitive enzymes, including creatine kinase, xanthine oxidoreductase, and glutaredoxin (GRX). Cells overexpressing GRX exhibited reduced cellular protein S-glutathionylation (PSSG) and absence of NTG tolerance, whereas those with silenced GRX showed increased extent of NTG-induced tolerance. Incubation of LLC-PK1 cells with oxidized glutathione led to several major observations associated with nitrate tolerance, namely, reduced cGMP accumulation, PSSG formation, superoxide accumulation, and the attenuation of these events by vitamin C. Aortic S-glutathionylated proteins increased approximately 3-fold in rats made tolerant in vivo to NTG and showed significant negative correlation with vascular responsiveness ex vivo. NTG incubation in EA.hy926 endothelial cells and LLC-PK1 cells led to increased S-glutathionylation and activity of p21(ras), a known mediator of cellular signaling. These results indicate that the hallmark events of NTG tolerance, such as reduced bioactivation and redox signaling, are associated with GRX-dependent protein deglutathionylation.

Arsine toxicity treated with red blood cell and plasma exchanges

BACKGROUND

Acute toxicity due to inhalation of arsine gas (AsH(3)) has no known antidote. Exchange transfusion may be beneficial, and dialysis is often required because arsine may cause acute intravascular hemolysis and renal failure. A patient with arsine toxicity has recently been treated by both red blood cell exchange (RBC-E) and plasma exchange (PE) therapy and our experience is reported.

CASE REPORT

A 46-year-old man was accidentally and unknowingly exposed to arsine gas while observing an industrial procedure. Within 6 hours he developed fatigue, nausea, vomiting, and tingling in his extremities and voided dark urine. He quickly developed renal failure secondary to acute arsine toxicity (arsenic level, 1250 microg/L). Laboratory findings were a hematocrit level of 24 percent; blood urea nitrogen and creatinine, 84 and 5.5 mg per dL, respectively; bilirubin, 9.1 mg per dL; indirect bilirubin, 6.8 mg per dL; haptoglobin, less than 6 (normal, 30-200); and lactic dehydrogenase, 10,413 units per L (normal, 265-580). An emergent 1-vol RBC-E transfusion by continuous-flow method revealed dramatic black, grossly hemolyzed plasma. After two additional RBC-E and two PE and daily hemodialysis, he completely recovered over the course of 1 month.

CONCLUSION

Patients with arsine toxicity resulting in intravascular hemolysis should receive RBC-E as soon as possible. In addition, PE may be beneficial in removing the components of RBC lysis and further reducing arsenic levels.

Heavy Metal Poisoning: Clinical Presentations and Pathophysiology

Humans have had a long and tumultuous relationship with heavy metals. Their ubiquitous nature and our reliance on them for manufacturing have resulted at times in exposures sufficient to cause systemic toxicity. Their easy acquisition and potent toxicity have also made them popular choices for criminal poisonings. This article examines the clinical manifestation and pathophysiology of poisoning from lead, mercury, arsenic, and thallium.

The metabolism of inorganic arsenic oxides, gallium arsenide, and arsine: a toxicochemical review

The aim of this review is to compare the metabolism, chemistry, and biological effects to determine if either of the industrial arsenicals (arsine and gallium arsenide) act like the environmental arsenic oxides (arsenite and arsenate). The metabolism of the arsenic oxides has been extensively investigated in the past 4 years and the differences between the arsenic metabolites in the oxidation states +III versus +V and with one or two methyl groups added have shown increased importance. The arsenic oxide metabolism has been compared with arsine (oxidation state -III) and arsenide (oxidation state between 0 to -III). The different metabolites appear to have different strengths of reaction for binding arsenic (III) to thiol groups, their oxidation-reduction reactions and their forming an arsenic-carbon bond. It is unclear if the differences in parameters such as the presence or absence of methyl metabolites, the rates of AsV reduction compared to the rates of AsIII oxidation, or the competition of phosphate and arsenate for cellular uptake are large enough to change biological effects. The arsine rate of decomposition, products of metabolism, target organ of toxic action, and protein binding appeared to support an oxidized arsenic metabolite. This arsine metabolite was very different from anything made by the arsenic oxides. The gallium arsenide had a lower solubility than any other arsenic compound and it had a disproportionate intensity of lung damage to suggest that the GaAs had a site of contact interaction and that oxidation reactions were important in its toxicity. The urinary metabolites after GaAs exposure were the same as excreted by arsenic oxides but the chemical compounds responsible for the toxic effects of GaAs are different from the arsenic oxides. The review concludes that there is insufficient evidence to equate the different arsenic compounds. There are several differences in the toxicity of the arsenic compounds that will require substantial research.

In-vitro studies of aluminium-induced toxicity on kidney proximal tubular cells

The toxicity of aluminium (Al) to various cells is well described. However, little is known about its effect on kidney cells, which can be exposed to relatively high concentrations. In this study, the effect of aluminium as the citrate complex in concentrations up to 100 microM/l was investigated using a monolayer cell culture of kidney proximal tubular cells (PTC). Aluminium was found to be slightly toxic; at 100 microM/l the PTCs lost viability by 15, 20 and 24% after incubation for 24, 48 and 72 h, respectively. Viability was significantly reduced (P<0.001) after 48 h incubation with aluminium concentrations of 25, 50, 75 and 100 microM/l compared with controls. Lactate dehydrogenase (LDH) release was significantly increased (P<0.001) with 100 microM/l Al to 44.67+/-1.76 and 50.33+/-0.88 compared with controls 24+/-1.00 and 28.33 2.34 U/l after 24 and 48 h incubation, respectively, indicating damage to the plasma membrane. However, N-acetyl-beta-D-glucosaminidase (NAG) release in the medium of cells exposed to aluminium showed no difference from control values (P>0.1). Glucose consumption in aluminium-exposed cells at 100 microM/l was slightly, but not significantly (P=0.14), increased during 48 h incubation. Electron micrographs of cells exposed to aluminium at 100 microM/l showed a slight reduction in microvilli density and the cell tight junctions were not as clear compared with the control cells. Pretreatment with protective agents glutathione and tiopronin partly restored the viability of kidney proximal tubular cells to control values, whereas vitamin C and/or cysteine showed no effect. This study indicates that aluminium may show toxicity to kidney cells in culture. Several sites on the cell, i.e. microvilli, membrane and the cell junction, seem to be affected, however the mechanism(s) of damage remain unclear.