Abstract
Amphotericin B is a polyene macrolide antibiotic known to induce cation-selective pore formation in biological cell membranes. Application of amphotericin B damages different type of cells and causes cell death. We investigated the mechanism of amphotericin B induced cell death and found that Cl− ion permeability was essential for the effect of amphotericin B. Fist we applied amphotericin B to Xenopus oocytes and found that 3μg/ml of amphotericin B was sufficient to burst oocytes in several hours in control NaCl solution. Replacement of extra-cellular Cl− by gluconate− completely blocked amphotericin B induced cell death. Replacement of extra-cellular Na+ by K+ had no effect. We examined many chemicals and found that 100 μM N-ethylmaleimide (NEM) or 100 μM chloroquine inhibited amphotericin B induced cell death. Both chemicals are known to inhibit the lysosomal proton pump. Two electrode voltage-clamp study of Xenopus oocytes was also performed. Amphotericin B induced cation selective conductance increase and both NEM and chloroquine had no effect on amphotericin B induced conductance increase. These evidences suggest that the influx of Cl− ions through endogenous Cl− channels, caused by amphotericin B induced cationic permeability increase, may induce lysosomal acidification and then damage the oocyte cell membrane. [Jpn J Physiol 55 Suppl:S36 (2005)]
