Abstract
This paper reports the effects of amphotericin B, a polyene antibiotic, on the water and nonelectrolyte permeability of optically black, thin lipid membranes formed from sheep red blood cell lipids dissolved in decane. The permeability coefficients for the diffusion of water and nonelectrolytes (P(DDi)) were estimated from unidirectional tracer fluxes when net water flow (J(w)) was zero. Alternatively, an osmotic water permeability coefficient (P(f)) was computed from J(w) when the two aqueous phases contained unequal solute concentrations. In the absence of amphotericin B, when the membrane solutions contained equimolar amounts of cholesterol and phospholipid, P(f) was 22.9 +/- 4.6 microsec(-1) and P(DDHDH2O) was 10.8 +/- 2.4 microsec(-1). Furthermore, P(DDi) was < 0.05 microsec(-1) for urea, glycerol, ribose, arabinose, glucose, and sucrose, and sigma(i), the reflection coefficient of each of these solutes was one. When amphotericin B (10(-6)M) was present in the aqueous phases and the membrane solutions contained equimolar amounts of cholesterol and phospholipid, P(DDHDH2O) was 18.1 +/- 2.4 microsec(-1); P(f) was 549 +/- 143 microsec(-1) when glucose, sucrose, and raffinose were the aqueous solutes. Concomitantly, P(DDi) varied inversely, and sigma(i) directly, with the effective hydrodynamic radii of the solutes tested. These polyene-dependent phenomena required the presence of cholesterol in the membrane solutions. These data were analyzed in terms of restricted diffusion and filtration through uniform right circular cylinders, and were compatible with the hypothesis that the interactions of amphotericin B with membrane-bound cholesterol result in the formation of pores whose equivalent radii are in the range 7 to 10.5 A.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.