Arsenic respiratory toxicity

Most forms of soluble arsenic are toxic to living organisms. Arsenate, a phosphate analog, uncouples respiratory chain phosphorylation due to the facile... 

The literature emphasizes that arsenic metabolism and toxicity vary greatly between species and that its effects are significantly altered by numerous physical, chemical, and biological modifiers. Adverse health effects, for example, may involve respiratory, gastrointestinal, cardiovascular, and hematopoietic systems, and may range from reversible effects to cancer and death, depending partly on the physical and chemical forms of arsenic tested, the route of administration, and the dose. 

Anaerobic metabolism occnrs nnder conditions in which the diffusion rate is insufficient to meet the microbial demand, and alternative electron acceptors are needed. The type of anaerobic microbial reaction controls the redox potential (Eh), the denitrification process, reduction of Mu and SO , and the transformation of selenium and arsenate. Keeney (1983) emphasized that denitrification is the most significant anaerobic reaction occurring in the subsurface. Denitrification may be defined as the process in which N-oxides serve as terminal electron acceptors for respiratory electron transport (Firestone 1982), because nitrification and NOj" reduction to produce gaseous N-oxides. hi this case, a reduced electron-donating substrate enhances the formation of more N-oxides through numerous elechocarriers. Anaerobic conditions also lead to the transformation of organic toxic compounds (e.g., DDT) in many cases, these transformations are more rapid than under aerobic conditions. 

Owens, E.J., Weimer, J.T., Ballard, T.A., Ford, D.F., Samuel, J.B., Hopcus, M.W., Merkey, R.P., and Olson, J.S. Ocular, cutaneous, respiratory and Intratracheal toxicity of solutions of CS and EA 3547 In glycol and glycol ether in animals. U.S. Army Medical Research Laboratory, Edgewood Arsenal, Md. 

Given the toxicity of ROS, it would have been remarkable if they had not been exploited to do intentional damage in some biological context. Indeed, the respiratory burst of neutrophils and macrophages is a crucial element of our antimicrobial arsenal. Superoxide is produced by NADPH oxidase of activated phagocytic cells and can account for up to 90% of their O2... 

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