Hereć Monika, Dziubińska Halina, Trebacz Kazimierz, Morzycki Jacek W, Gruszecki Wiesław I
Department of Biophysics, Institute of Physics, Maria Curie-Skłodowska University, Pl. Marii Curie-Sklodowskiej 1, 20-031 Lublin, Poland.
Biochem Pharmacol. 2005 Sep 1;70(5):668-75. doi: 10.1016/j.bcp.2005.06.001.
A pH sensitive fluorescence probe piranine trisulfonate, entrapped inside small unilamellar liposomes formed with egg yolk phosphatidylcholine, was applied to investigate effect of polyene antibiotic amphotericin B (AmB) on proton transport across lipid membranes. Time dependencies of fluorescence-monitored pH changes inside lipid vesicles, upon sudden acidification of the liposome suspension, were analyzed in terms of two-exponential kinetics. It appears that addition of AmB at 3 mol%, with respect to lipid, considerably increases the rate constant of the fast component of proton transport (a change from (60 to 149) x 10(-3)s(-1)) and decreases the rate constant of the slow component (a change from (11 to 5) x 10(-3)s(-1)). Incorporation of 0.1 mol% AmB results in the decrease of both parameters (to (33 and 2) x 10(-3)s(-1), respectively). The increase in the rate of proton transfer across the lipid membrane is interpreted as related to the formation of membrane channels by AmB, at higher concentration of the drug or nonspecific destabilization of the membrane structure. At low concentrations, at which formation of molecular structures of AmB is not possible, the antibiotic molecules are oriented horizontally with respect to the plane of the membrane and act in making the membrane more compact and less permeable to ions. The presence of sterols (cholesterol, ergosterol and cholesterol dimer) in the lipid phase, in the concentration 3 mol% and lower, decreased the rate constants of proton transfer across the membranes but did not influence significantly the effect of AmB on the ion transport. The presence of AmB in the bathing solutions of tonoplast membranes isolated from Conocephalum conicum at the concentrations range 1 x 10(-7) to 3.6 x 10(-5) does not influence considerably the ion current, as monitored by means of the patch-clamp technique.
一种包裹在由蛋黄磷脂酰胆碱形成的小单层脂质体内的pH敏感荧光探针三磺酸盐吡喃宁，被用于研究多烯抗生素两性霉素B（AmB）对质子跨脂质膜转运的影响。根据双指数动力学分析了脂质体悬浮液突然酸化后，脂质囊泡内荧光监测的pH变化的时间依赖性。结果表明，相对于脂质，添加3 mol%的AmB可显著提高质子转运快速成分的速率常数（从(60到149)×10(-3)s(-1)变化），并降低慢速成分的速率常数（从(11到5)×10(-3)s(-1)变化）。掺入0.1 mol%的AmB会导致两个参数均降低（分别降至(33和2)×10(-3)s(-1)）。质子跨脂质膜转移速率的增加被解释为与AmB在较高药物浓度下形成膜通道或膜结构的非特异性破坏有关。在低浓度下，AmB无法形成分子结构，抗生素分子相对于膜平面水平排列，使膜更致密且对离子的渗透性更低。脂质相中3 mol%及更低浓度的甾醇（胆固醇、麦角甾醇和胆固醇二聚体）的存在降低了质子跨膜转移的速率常数，但对AmB对离子转运的影响没有显著影响。在1×10(-7)至3.6×10(-5)的浓度范围内，从角果藻分离的液泡膜的浴液中存在AmB，通过膜片钳技术监测，对离子电流没有显著影响。
