Speciation 98: Abstracts

Despite an abundant literature the physiopathological role of aluminum is far to be well understood. Among principal problems first of all it is necessary to remember that the chemistry of Al(III) in biological systems is rather complex and secondly, the choice of good and reliable biological models is not an easy task In this communication some studies on the effects produced by Al(III) at subcellular level using isolated cell membranes, lysosomes, endoplasmic reticulum (ER) and mitochondria will be presented. The way how Al(III) is internalized into the cell is not completely defined and the transferrin- receptor pathway is certainly not the only one. Most likely, according to recent literature, phenomena such as diffusion, endocytosis/pinocytosis or controlled transcytosis cannot be excluded on the basis also of some preliminary results obtained in our laboratory. In this context the physico-chemical properties of the metal-ion coordination sphere can be of discriminating relevance in defyining the way of Al(III) entering into the cell. Certainly, Al(III) is able to modify the physico-chemical properties of the cell membranes increasing their rigidification and fragility as well as modifying properties of pores or channels (e.g., VDAC)¹. In mitochondria Al(III) is able to deeply modify Ca²⁺ homeostasis altering for instance Na⁺/Ca²⁺ antiport exchange². In certain pathologies Al(III) has been observed to accumulate in lysosomes and in this connection recently, we have demonstrated that Al(III) ihibits the lysosomal proton-pump as well as the activity of some lysosomal enzymes³. In conclusion, the scenario of Al(III) toxicity is very complex and far to be totally clear. There is no doubt that to overcome basic interpretative difficulties more interdisciplinary work is needed.This is the reason why we have open an aluminum web site with the aim to involve all scientits interested to share collaborative projects in order to better understand molecular mechanisms implicated in aluminum toxicity.

http://www.bio.unipd.it/~zatta/aluminum.html

References

1. Gandolfi L., Stella M.P., Zambenedetti P. and Zatta P. (1998) Biochim. Biophys. Acta (In press).
2. Mirzabekov T., Ballarin C., Nicolini M., Zatta P. and Sorgato C. (1993) J. Membr. Biol. 133: 129-143.
3. Zatta et al. (In preparation)

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