Site and mechanism of enhanced gastrointestinal absorption of aluminum by citrate

Froment, Daniel P.H.; Molitoris, Bruce A.; Buddington, Bruce; Miller, Norman F.; Alfrey, Allen C.

doi:10.1038/ki.1989.290

Cited by 145 publications

(49 citation statements)

References 27 publications

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“…It is now established that alu minium absorption occurs in the stomach |6] and in the small intestine by a paracellular pathway process via the tight junctions | llJ|. We do not observe any reactive deposit in the duodenal mucosa, while previous biochemical exper iments suggest that those could occur [7], These contradic tory results can be explained by a lack of sensitivity of histo chemical methods. In the stomach, the localization of metallic deposits in the antrum only can be explained by differences in the permeability of the mucosa between the fundus and the antrum.…”

Section: Discussioncontrasting

confidence: 52%

Aluminium Hydroxide Uptake in the Stomach and in the Intestine of the Rat: A Histochemical Study

Moré

Fioramonti²,

Buéno³

1992

Cells Tissues Organs

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Using the histochemical stains aluminon, solochrome azurine and solochrome cyanine, intracellular binding of aluminium was examined in the mucosa of the stomach, duodenum, jejunum and ileum of adult rats. A first group of rats (n = 42) was sacrificed 1, 3, 6, 12, 24, 48 and 96 h after a single (300 mg × kg^–1) oral administration of aluminium hydroxide. A second group of animals (n = 30) received daily the same dose of Al(OH)₃ and was euthanatized after 3, 4, 5, 6 and 7 days of treatment. Aluminium deposits occurred only in the antral glands of the stomach and in rats treated for at least 3 days. The reactive deposits are located in the cytoplasm of the upper glandular cells and in the lumen of the antral glands. These results suggest that aluminium is absorbed through the antral mucosa and may be re-excreted through the glandular mucus flow into the digestive lumen where it will be absorbed again. We hypothesize that the metal could act as a delayed-effect drug.

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Section: Discussioncontrasting

confidence: 52%

Aluminium Hydroxide Uptake in the Stomach and in the Intestine of the Rat: A Histochemical Study

Moré

Fioramonti²,

Buéno³

1992

Cells Tissues Organs

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“…A1 in the presence of citrate appears to be largely absorbed by the paracellular pathway through imperfect tight junctions (Froment et al 1989a), probably because citrate chelates intramucosal Ca. Not all A1 absorption necessarily occurs in this manner, since the A1 species present in the lumen of the gastrointestinal tract will dictate how it is taken up by the mucosa.…”

Section: Mechanisms Of a B S O R P T I O Nmentioning

confidence: 99%

The chemistry of aluminium in the gastrointestinal lumen and its uptake and absorption

Powell

Thompson

1993

Proc. Nutr. Soc.

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A large number of experimental studies have been carried out on the intestinal absorption and/or uptake of Al, and on the factors that affect this. However, apart from the well-known problems of contamination and the difficulty of analysis of Al, many of these studies have been flawed, particularly when experimental solutions have been used, since often it has not been realized that the A1 has precipitated at physiological pH. Other problems have included inappropriate use of buffers (such as containing phosphate) and extrapolation of results from unphysiologically high levels to dietary levels.Here we shall assess the chemistry, uptake and absorption of A1 from the gastrointestinal tract, and in particular consider the importance of dietary, rather than pharmacological, levels to which the general population is exposed.

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“…As mentioned above, citrate increased absorption of aluminum as the chloride from the in situ rat gut preparation (60). Froment et al (75), in an examination of the mechanism of enhancement of aluminum uptake by citrate, tested the hypothesis that citrate increases the permeability of the tight junctions between intestinal epithelial cells. The investigators excised the duodena of rats, added a solution of ruthenium red, and filled each gut section with either aluminum chloride or aluminum citrate.…”

Section: Specific Sources Of Exposurementioning

confidence: 99%

The biological speciation and toxicokinetics of aluminum.

DeVoto

Yokel

1994

Environ Health Perspect

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This review discusses recent literature on the chemical and physiological factors that influence the absorption, distribution, and excretion of aluminum in mammals, with particular regard to gastrointestinal absorption and speciation in plasma. Humans encounter aluminum, a ubiquitous yet highly insoluble element in most forms, in foods, drinking water, and pharmaceuticals. Exposure also occurs by inhalation of dust and aerosols, particularly in occupational settings. Absorption from the gut depends largely on pH and the presence of complexing ligands, particularly carboxylic acids, with which the metal can form absorbable neutral aluminum species. Uremic animals and humans experience higher than normal body burdens of aluminum despite increased urinary clearance of the metal. In plasma, 80-90% of aluminum binds to transferrin, an iron-transport protein for which receptors exist in many tissue. The remaining fraction of plasma aluminum takes the form of small-molecule hydroxy species and small complexes with carboxylic acids, phosphate, and, to a much lesser degree, amino acids. Most of these species have not been observed in vivo but are predicted from equilibrium models derived from potentiometric methods and NMR investigations. These models predict that the major small-molecule aluminum species under plasma conditions are charged and hence unavailable for uptake into tissues.

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Site and mechanism of enhanced gastrointestinal absorption of aluminum by citrate

Cited by 145 publications

References 27 publications

Aluminium Hydroxide Uptake in the Stomach and in the Intestine of the Rat: A Histochemical Study

Aluminium Hydroxide Uptake in the Stomach and in the Intestine of the Rat: A Histochemical Study

The chemistry of aluminium in the gastrointestinal lumen and its uptake and absorption

The biological speciation and toxicokinetics of aluminum.

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