CHANGES IN THE ACTIVITIES OF VOLUME-REGULATORY ION CHANNELS DURING CELL DIFFERENTIATION OF MOUSE B LYMPHOCYTES.

包括T淋巴细胞在内的多种细胞在KC1外溢引起的初始渗透性肿胀后，可以在低渗介质中重新调节其体积。然而，在成熟的人B淋巴细胞中未发现调节体积减少（RVD） （Grinstein, 1983）。支持这一观察，我们发现成熟的小鼠B细胞系（DW 101）在低渗条件下几乎没有体积调节能力。此外，小鼠b前细胞系（dw34、dw8和abelson白血病病毒转化的b前细胞系）在几十分钟内也未出现RVD。相比之下，pre-pre-B细胞系（scid7， abelson病毒转化的pre-pre-B）在低渗胁迫下可以表现出快速的体积调节。升高细胞外K^+浓度可抑制RVD，降低细胞外C1^-通道阻滞剂（sit）可抑制pre-pre-B细胞的RVD。当加入阳离子离子载体（gramicidine）时，在低na ^+条件下，在低压肿胀的前b细胞中观察到RVD。因此，我们认为RVD机制（可能是K^+转运蛋白）在小鼠b系细胞分化的前b阶段受到损害。事实上，贴片电极的全细胞记录显示，在低渗刺激下，Abelson pre-pre-B细胞系中的K^+和C1^-电流都被激活，但在低渗应激后，pre-B细胞系中只有后者通道被激活。

A variety of cell species, including T lymphocytes, can readjust their volume in a hypotonic medium after the initial osmotic swelling due to KC1 effluxes. However, no regulatory volume decrease (RVD) has been found in mature human B lymphocytes (Grinstein, 1983). Supporting this observation, we found that a mature murine B cell line (DW 101) has little ability of the volume regulation under hypotonic conditions. In addition, mouse pre-B cell lines (DW 34, DW 8 and an abelson leukemia virustransformed pre-B cell line) were also found to exhibit no RVD within several tens ofminutes. In contrast, pre-pre-B cell lines (SCID 7, abelson virus-transformed pre-pre-B) could show rapid volume regulation upon hypotonic stress. The RVD was suppressed by elevating the extracellular K^+ concentration and facilitated by reducing the extracellular C1^- channel blocker (SITS) inhibited the RVD of pre-pre-B cells. When a cationic ionophore (gramicidine) was added, the RVD was observed i n hypotonically swollen pre-B cells under the low-Na^+ condition. Thus, it is suggested that the RVD mechanism (presumably K^+ transporters) becomes impaired during the mouse B-lineage cell differentiation at the pre-B stage. In fact, whole-cell recordings with patch electrodes showed that both K^+ and C1^- currents became activated in an Abelson pre-pre-B cell line upon a hypotonic challenge, but that only the latter channel was activated in the pre-B cell line after hypotonic stress.