[Study of the volt-ampere characteristics of ion channels by transmembrane current harmonics]

A method is proposed for measuring the coefficient of non--linearity beta of current--voltage characteristics of the class i (U) approximately U (1 + beta U2) of ionic channels formed by grammicidine A (Gra) and amphotericine B by the 3rd harmonics of the membrane current. For Gra A beta depends on the concentration of electrolyte c increasing lg c from -17 B-2 at 0.03 M to 8 B-2 at 3.4 M KCl turning to 0 at c0 = 0.3 divided by 1 M. The membranes of egg lecithin and glycerylmonooleate (GMO) differ in c0 value. Substitution of K+ ion for Li+, of the membrane solvent (n-heptane for n-hexadecane) and freezing of the GMO membrane do not affect beta.