Action potentials, effect aluminum

Blaustein and Goldman, using the voltage clamp technique, studied the effects of aluminum on action potential generation in lobster axons in vitro. When aluminum in concentrations as low as 0.03 mEq/L was substituted for calcium in the bathing medium, the action potential was blocked. They also observed a significant effect when aluminum was added to normal seawater. Aluminum caused a marked reduction of early transient current and also reduced the steady-state current. 

Using mice, the objective of this project is to determine biological actions relevant to toxicological effects, and clarify potential human health risks associated with ingestion of aluminum in food, water, and pharmaceuticals. 

Fluoroaluminate complexes can mimic the action of many hormones, neurotransmitters, and growth factors. G-protein-mediated cell responses are key steps in neurotransmission and intercellular signaling in the brain [20], and TFA acts as an active stimulatory species [21]. Exposure of osteoblasts to TFA results in a marked potentiation of intracellular orthophosphate transport, alluding to the anion s ability to increase bone mineralization [22]. Brief exposure to aluminum fluoride complexes induces prolonged enhancement of synaptic transmission [23] and can potentially affect the activity of many other ion channels and enzymes in the kidney [24]. Rapid and dynamic changes of the cytoskeletal actin network are of vital importance to the motility of many cells, and TFA induction effects a pronounced and sustained... 

The third article, appearing in the February/March 2003 issue, is concerned with ways to avoid fluoride accidents, namely an overdose, and describes how a city can reject fluoridation, a course of action beset with difficulties, however. Among the adverse effects cited is that fluoride can affect the central nervous system and thus serves as a neurotoxicant. Moreover, there is a correlation between water fluoridation and increased hip fractures for persons 65 years and older, and a correlation for a decrease in fertility rates. Furthermore, fluoride is a potential carcinogen, and is a known inhibitor for many enzymes involved in cell metabolism. It is mentioned that fluoride disposal is costly, requiring a class-one landfill, and would be an added cost for the aluminum and fertilizer industries, which produce fluoride as a waste byproduct. The ready alternative is to dispose of it via water fluoridation and toothpaste, although the risks have been found to outweigh the benefits, and fluoridation is outlawed in most of Western Europe, for instance. 

Two developments led neuroscientists as well to reexamine aluminum as a potential neurotoxicant. One was the discovery that aluminum played a role in the encephalopathy associated with kidney dialysis. The other was the implication that it was associated with senile dementia of the Alzheimer type. The connection with dialysis encephalopathy has been established, although a suitable animal model is lacking. The association with Alzheimer s disease is tenuous, but the issue has stimulated a considerable body of work that both illuminates the biological actions of aluminum and provides further knowledge of degenerative processes in the nervous system. The behavioral data in laboratory animals are ambiguous because, to achieve effects, many experimenters have administered the aluminum intracranially, a mode of administration with obvious pitfalls. A useful summary of the recent literature appears in the volume edited by Liss. ... 

Thus, we have clearly made large advances in understanding the effects of aluminum, and are now at a point that the research pace should quicken. Fortunately aluminum does not present an environmental hazard, but its potential role in human disease and use as a neurobiological tool Wcirrcmt further research to understand the mechanisms of its actions. 

A marked increase in aluminum Ep values towards anodic potentials was observed in the presence of marcescens, even in the sterile medium, suggesting the metal surface may experience some protective action by these bacteria. Local acidification enhanced by adhesion processes taking place at the metal/mycelia interface accounts for some of the specific effects of resinae in the corrosion process of aluminum alloys in fuel/water systems (Salvarezza et al., 1979). The acidification also has been reported in the literature as a differential effect between two Pseudomonas spp. in relation to aluminium corrosion. Acidity can prevent repasivation and may hinder the formation of a protective oxide film. Therefore, under acidic conditions, pitting of the metal by chloride anions occurs at more cathodic potentials than in neutral solution (Salvarezza et al., 1983). 

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