Streptolysin O (SLO) is a bacterial pore-forming toxin that is employed to permeabilize cell membranes in some biological experiments. SLO forms various types of pores with different shapes, increasing membrane ion permeability and subsequently inducing changes in membrane potential. To characterize the pores formed by SLO, the changes in membrane potential induced by SLO in rat lymphocytes were considered using flow cytometry with a voltage-sensitive fluorescent probe, bis-(1,3-dibutylbarbituric acid)trimethine oxonol (Oxonol). SLO caused three types of membrane potential responses accessed with Oxonol. One type induces a great decrease in Oxonol fluorescence (large hyperpolarization) that may be elicited via the increase of Ca2+ -dependent K+ permeability by SLO-induced influx of external Ca2+ . A second type is an increase in Oxonol fluorescence (depolarization) that may be caused by a nonspecific increase in membrane cation permeability. The third type is a small decrease in Oxonol fluorescence (small hyperpolarization), probably via an increase in Cl- permeability. That SLO transitionally changes membrane ion permeability may have implications in the pathology of pyogenic group streptococci infections in which SLO is thought to be one of the key virulence factors.

中文翻译：

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链球菌溶血素O（一种形成孔的毒素）诱导的膜电位的变化：使用压敏荧光探针和大鼠胸腺淋巴细胞的流式细胞仪分析。

链球菌溶血素O（SLO）是一种细菌性造孔毒素，在某些生物学实验中可用于透化细胞膜。SLO形成具有不同形状的各种类型的孔，从而增加了膜离子的渗透性，并随后引起了膜电势的变化。为了表征由SLO形成的孔，使用流变细胞仪结合电压敏感的荧光探针bis-（1,3-dibutylbarbituricic acid）trimethine oxonol（Oxonol），考虑了SLO诱导的大鼠淋巴细胞膜电位的变化。SLO导致使用Oxonol进行的三种类型的膜电位反应。一种类型引起氧合醇荧光的大幅降低（大的超极化），这可能是由于SLO诱导的外部Ca2 +的流入增加了Ca2 +依赖的K +渗透性而引起的。第二种是氧合酚荧光的增加（去极化），这可能是由膜阳离子渗透性的非特异性增加引起的。第三类可能是通过增加Cl的渗透性，使Oxonol的荧光性降低很小（小的超极化）。SLO会暂时改变膜离子通透性，这可能在化脓性链球菌感染的病理中具有影响，在化脓性链球菌感染中，SLO被认为是关键的毒力因子之一。