title: Gramicidin, valinomycin, and cation permeability of Streptococcus faecalis.
abstract: Gramicidin and valinomycin in concentrations of 10(-7) and 10(-6)m, respectively, inhibited the growth of Streptococcus faecalis. Inhibition of growth was associated with loss of Rb(+) and K(+) from the cells, and could be reversed by addition of excess K(+). Cells treated with these antibiotics exhibited greatly increased permeability to certain cations; no effect was observed on the penetration of other small molecules. Unlike normal cells, cells treated with gramicidin rapidly lost internal Rb(+) by passive exchange with external cations, including H(+), all monovalent alkali metals, NH(4) (+), Mg(++), and tris(hydroxymethyl)aminomethane. Exchange was rapid even at 0 C and was independent of energy metabolism. The effect of valinomycin was more selective. Cellular Rb(+) was rapidly displaced by external H(+), K(+), Rb(+), and Cs(+); other cations were less effective. The exchange was independent of metabolism but strongly affected by temperature. Under certain conditions, polyvalent cations inhibited exchange between (86)Rb and Rb(+) induced by valinomycin. The antibiotic apparently neither stimulates nor inhibits the energy-dependent K(+) pump of S. faecalis, but exerts its effect on the passive permeability of the membrane to cations. The increased permeability to specific cations induced by gramicidin and valinomycin is a sufficient explanation for the inhibition of growth, glycolysis, and other processes.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002247:Carbon Isotopes; D002463:Cell Membrane Permeability / Q000187:drug effects*; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000378:metabolism; D006019:Glycolysis / Q000187:drug effects; D010759:Phosphorus Isotopes; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D013696:Temperature; D014449:Tyrothricin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D002247:Carbon Isotopes; D010759:Phosphorus Isotopes; D014449:Tyrothricin; D012413:Rubidium; D011188:Potassium