THE PERMEABILITY OF PINCHED-OFF NERVE ENDINGS TO SODIUM, POTASSIUM AND CHLORIDE AND THE EFFECTS OF GRAMICIDIN

Abstract—

• 1 The passive permeability of synaptosomes to ions was measured by a light-scattering technique. Synaptosomes were freely permeable to acetate, HCO₃^_, SCN^?and NH₄⁺ and were impermeable to choline and SO₄^2-.
• 2 Gramicidin D selectively increased the permeability of synaptosomes to Na⁺ and K⁺ ions.
• 3 The relative permeabilities of Na⁺, K⁺ and Cl^?, measured in the presence of a number of more permeant counter-ions, was in the ratio 1:19:12. These values are discussed in terms of the source of the resting potential.