Al and Ca Alteration of Membrane Permeability of Quercus rubra Root Cortex Cells

This study was undertaken to quantify the effect of aluminum and calcium on membrane permeability. The influence of Ca²⁺ (0.2-3.7 millimolar) and Al³⁺ (0-3.7 millimolar) on the permeability of root cortical cells of Quercus rubra was measured using three nonelectrolytes (urea, methyl urea, and ethyl urea) as permeators of progressively increasing lipid solubility. Water permeability was also measured. Al³⁺ (a) increased membrane permeability to the nonelectrolytes, (b) decreased the membrane's partiality for lipid permeators, and (c) decreased membrane permeability to water. Ca²⁺ had effects on permeability that were opposite to those of Al³⁺. When Al³⁺ and Ca²⁺ were tested in combination, these opposite effects counteracted each other. The results suggest that Al³⁺ altered the architecture of membrane lipids.