Burt J M, Duenas C J, Langer G A
Circ Res. 1983 Nov;53(5):679-87. doi: 10.1161/01.res.53.5.679.
Polymyxin B, an amphiphilic, cationic peptidolipid, which is thought to bind to anionic phospholipids in cell membranes, is shown to interact with the cellular calcium of cultured neonatal rat myocardial cells in a dose-dependent, partially reversible manner. At concentrations of less than or equal to 0.1 mM, it has two distinct effects. First, it results in displacement of 1.4 +/- 0.3 mmol Ca/kg dry weight, which is equivalent to 18.1 +/- 3.4% of the total exchangeable cellular calcium. Total calcium displaced by polymyxin B and a nonspecific cationic probe, lanthanum, at its maximal displacing concentration (1 mM), was 5.9 +/- 1.3 mmol/kg dry weight. Thus, the total displaceable calcium represented 76.3 +/- 2.5% of the total exchangeable calcium. Second, polymyxin B (less than or equal to 0.1 mM) causes a reduction in net uptake of calcium, and slows the efflux of both calcium and potassium. Concentrations of polymyxin B higher than 0.1 mM result in an initial displacement of calcium, followed by an irreversible and sustained period of enhanced net calcium uptake. Efflux of calcium is slowed at the higher polymyxin B concentrations, whereas efflux of potassium is enhanced. Cellular contractile activity and electrical activity are irreversibly altered only by the higher concentrations. The results suggest that polymyxin B is a useful probe for the role of membrane phospholipids in control of ion binding and fluxes.
多粘菌素B是一种两亲性阳离子肽脂，被认为可与细胞膜中的阴离子磷脂结合，已证明它能以剂量依赖性、部分可逆的方式与培养的新生大鼠心肌细胞的细胞钙相互作用。在浓度小于或等于0.1 mM时，它有两种不同的作用。首先，它导致1.4±0.3 mmol钙/千克干重的置换，这相当于细胞可交换总钙的18.1±3.4%。多粘菌素B和非特异性阳离子探针镧在其最大置换浓度（1 mM）下置换的总钙为5.9±1.3 mmol/千克干重。因此，可置换的总钙占可交换总钙的76.3±2.5%。其次，多粘菌素B（小于或等于0.1 mM）会导致钙的净摄取减少，并减缓钙和钾的外流。高于0.1 mM的多粘菌素B浓度会导致钙的初始置换，随后是不可逆且持续的净钙摄取增加期。在较高的多粘菌素B浓度下，钙的外流减缓，而钾的外流增强。只有较高浓度的多粘菌素B才会不可逆地改变细胞收缩活动和电活动。结果表明，多粘菌素B是研究膜磷脂在控制离子结合和通量中作用的有用探针。
