Amphotericin B and Nystatin show different activities on sterol-free vesicles.
It has generally been assumed that the polyene antibiotics Nystatin and Amphotericin B cause membrane damage by the same mechanism. However, using kinetic fluorescence methods we have found that AmB and Nystatin have very different activities on sterol-free dioleoyl phosphatidylcholine and egg phosphatidylcholine small unilamellar vesicles. At very low AmB concentrations (less than 1/1000 lipids in egg phosphatidylcholine) significant K+ permeability enhancement is observed. However, even at very high Nystatin to lipid ratios (1/100) very little K+ current is induced, particularly in dioleoyl phosphatidylcholine vesicles. The novel technique described here uses a K+/H+ exchange mechanism to detect minute transmembrane K+ currents by monitoring internal membrane vesicle pH changes with pyranine.
Whyte
B S
BS
Department of Chemistry, University of Wisconsin-Eau Claire 54702.
Peterson
R P
RP
Hartsel
S C
SC
D000666:Amphotericin B; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes; D008954:Models, Biological; D009761:Nystatin; D010539:Permeability; D010713:Phosphatidylcholines; D011188:Potassium
D008081:Liposomes; D010713:Phosphatidylcholines; D009761:Nystatin; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000666:Amphotericin B; C017251:1,2-oleoylphosphatidylcholine; D011188:Potassium