Control of membrane permeability in animal cells by divalent cations
The permeability of several cell lines, including HeLa, L929, 3T6 and T3, to various compounds is affected by the concentration of divalent cations in the culture medium. In the absence of Mg/sup 2 +/ ions but with 4-8 mM CaCl/sub 2/ in the medium, HeLa and L929 cells become permeabilized, as measured by the entry of the aminoglycoside antibiotic hygromycin B. However, 33 and 3T6 cells become much more permeable when calcium and magnesium are both absent from the medium. Addition of Mg/sup 2 +/ above 2 mM abolishes the permeabilization induced by Ca/sup 2 +/. Basic pH favors permeabilization, whereas acidic pH inhibits the entry of hygromycin B. Increased entry of macromolecules, such as the toxin alpha-sarcin, horseradish peroxidase (HRP) and luciferase, is also observed under permeabilization conditions, suggesting that this method could be of general use, since it is not harmful to cells and is fully reversible. Exit of /sup 86/Rb/sup +/ ions and (/sup 3/H)uridine-labelled nucleotides was also assayed. The authors did not observe increased release of these compounds from preloaded cells under various calcium concentrations. Finally, the effects of several inhibitors of endocytosis and other membrane functions on the permeabilization process were also analyzed. The entry of alpha-sarcin was not affected by nifedipine, dibucaine or mepacrine, but was partially inhibited by NH/sub 4/Cl, amantadine and chloroquine.
- Research Organization:
- Universidad Autonoma, Madrid, Spain
- OSTI ID:
- 6524188
- Journal Information:
- Exp. Cell Res.; (United States), Vol. 169:2
- Country of Publication:
- United States
- Language:
- English
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