title: The ion permeability induced in thin lipid membranes by the polyene antibiotics nystatin and amphotericin B.
abstract: Characteristics of nystatin and amphotericin B action on thin (<100 A) lipid membranes are: (a) micromolar amounts increase membrane conductance from 10(-8) to over 10(-2) Omega(-1) cm(-2); (b) such membranes are (non-ideally) anion selective and discriminate among anions on the basis of size; (c) membrane sterol is required for action; (d) antibiotic presence on both sides of membrane strongly favors action; (e) conductance is proportional to a large power of antibiotic concentration; (f) conductance decreases approximately 10(4) times for a 10 degrees C temperature rise; (g) kinetics of antibiotic action are also very temperature sensitive; (h) ion selectivity is pH independent between 3 and 10, but (i) activity is reversibly lost at high pH; (j) methyl ester derivatives are fully active; N-acetyl and N-succinyl derivatives are inactive; (k) current-voltage characteristic is nonlinear when membrane separates nonidentical salt solutions. These characteristics are contrasted with those of valinomycin. Observations (a)-(g) suggest that aggregates of polyene and sterol from opposite sides of the membrane interact to create aqueous pores; these pores are not static, but break up (melt) and reform continuously. Mechanism of anion selectivity is obscure. Observations (h)-(j) suggest-NH(3) (+) is important for activity; it is probably not responsible for selectivity, particularly since four polyene antibiotics, each containing two-NH(3) (+) groups, induce ideal cation selectivity. Possibly the many hydroxyl groups in nystatin and amphotericin B are responsible for anion selectivity. The effects of polyene antibiotics on thin lipid membranes are consistent with their action on biological membranes.
mesh_terms: D000666:Amphotericin B / Q000008:administration & dosage / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D055598:Chemical Phenomena; D002621:Chemistry; D002712:Chlorides; D004553:Electric Conductivity / Q000187:drug effects; D004594:Electrophysiology / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008055:Lipids; D008094:Lithium; D008564:Membrane Potentials / Q000187:drug effects; D008567:Membranes, Artificial; D009761:Nystatin / Q000008:administration & dosage / Q000494:pharmacology*; D011188:Potassium; D012964:Sodium; D013696:Temperature
chemical_list: D002712:Chlorides; D008055:Lipids; D008567:Membranes, Artificial; D009761:Nystatin; D000666:Amphotericin B; D008094:Lithium; D012964:Sodium; D011188:Potassium