Role of Water in the Aging of Aluminum Hydroxide Suspensions

Morefield, Elaine M.; Peck, Garnet E.; Feldkamp, Joseph R.; White, Joe L.; Hem, Stanley L.

doi:10.1002/jps.2600750418

Cited by 4 publications

(2 citation statements)

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“…Saturation values of soluble aluminium hydroxides in a neutral aqueous solution are presumably very low: 8 x 10-6M for Al(OH)-and 10-"M for Al(H2O)6+ (MacDonald & Martin, 1988). Several recent publications indicate that the trivalent cation is the biotoxic form of this substance (Martin, 1986;Birchall & Chappell, 1988 (Morefield et al, 1986). The dose of aluminium used in these experiments, 20-100, ugml 1, was chosen for the following two reasons.…”

Section: Activity Recordingmentioning

confidence: 99%

“…Permanent stirring ensured homogeneous distribution of the amorphous Al(OH)3. Presumably, no significant transition of the aluminium hydroxide to one of its crystalline forms took place during the few hours' long experiments (Morefield et al, 1986). The dose of aluminium used in these experiments, 20-100, ugml 1, was chosen for the following two reasons.…”

Section: Activity Recordingmentioning

confidence: 99%

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Effects of aluminium on electrical and mechanical properties of frog atrial muscle

Meiri

Shimoni

1991

British J Pharmacology

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The effects of aluminium on membrane ionic currents were studied in single cardiac myocytes. Most of the work was done on frog atrial cells, but some experiments were also carried out on single cells isolated from rabbit ventricles and atria. The effects of aluminium on the force of contraction of frog atrial trabeculae were also investigated. Aluminium was prepared from AlCl3 as a stock 0.5 m solution which has a pH of 3.5. Before each experiment, this solution was added to the control solution, to give a final concentration of 20–100 μg ml−1 aluminium (0.75–3.75 mm AlCl3). The solutions were brought to a pH of 7.4 or 7.6, at which they consist of a mixture of amorphous aluminium hydroxides and a very small amount of soluble ionic aluminium complexes: free aluminium cations (less than 10 pm), aluminohydroxide anions (less than 8 μm). The addition of this suspension reduced the peak inward calcium currents in single rabbit atrial and ventricular cells and in frog atrial cells. In the latter, the peak current was reduced (at + 10 mV) to 45% of control (mean of 9 cells). This effect was reversible upon washout, and was obtained at all membrane potentials, with no shift of the calcium current voltage relationship along the voltage axis. Aluminium also reduced the time‐dependent potassium current IK. This reduction was observed at all membrane potentials. For example, at + 10 mV, the mean reduction of IK (n = 9) was to 69% of the control amplitude. This effect, which was very difficult to reverse, was not due to IK rundown. The fully activated current‐voltage relationships (obtained by standard ‘tail’ analysis) showed that the effect of aluminium was due mainly to a decrease in conductance and not to a shift in the activation range of IK. The mean voltage of half activation was shifted by 8 mV in the depolarizing direction (n = 5). The background potassium current IK1 was also slightly but consistently changed in a complex fashion, with an outward shift at membrane potentials positive to −60 mV. For example, at a membrane potential of −40 mV, the mean shift was by 22 ± 4 pA. At more negative potentials, there was an inward shift in the current amplitudes. For example, for steps to −100 mV the current elicited was larger (more inward) by 53 pA (mean value, n = 10). The reversal potential was slightly shifted (< 10 mV) in the hyperpolarizing direction. The force of contraction of frog atrial trabeculae was altered by aluminium in a complex manner, which showed marked seasonal variation. During most of the year, 50–100 μg ml−1 aluminium caused a biphasic change, with an early small and consistent decrease, followed by a large increase in twitch amplitude. For a short period corresponding to the (local) winter months the sensitivity to aluminium was greatly enhanced. Aluminium 100 μg ml−1 totally abolished contraction (n = 5), while a lower concentration (20 μg ml−1) produced a sustained reduction in the force of contraction. Similar biphasic and seasonal responses have been reported to be induced by lanthanum. The biph...

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Section: Activity Recordingmentioning

confidence: 99%

Section: Activity Recordingmentioning

confidence: 99%