Partiseti M, Choquet D, Diu A, Korn H
Laboratoire de Neurobiologie Cellulaire, U261 INSERM, Institut Pasteur, Paris, France.
J Immunol. 1992 Jun 1;148(11):3361-8.
The expression and characteristics of K+ channels of human B lymphocytes were studied by using single and whole-cell patch-clamp recordings. They were gated by depolarization (voltage-gated potassium current, IKv, 11-20 pS) and by an increase in intracellular Ca2+ concentration (calcium-activated potassium current, IKCa, 26 pS), respectively. The level of expression of these channels was correlated with the activational status of the cell. Both conductances are blocked by tetraethylammonium, verapamil, and charybdotoxin, and are insensitive to apamin; 4-aminopyridine blocks IK, preferentially. We used a protein kinase C activator (PMA) or antibodies to membrane Ig (anti-mu) to activate resting splenocytes in culture. Although IKv was recorded in the majority of the resting lymphocytic population, less than 20% of the activated cells expressed this conductance. However, in this subset the magnitude of IKv was 20-fold larger than in resting cells. On the other hand, IKCa was detected in nearly one half of the resting cells, whereas all activated cells expressed this current. The magnitude of IKCa was, on average, 30 times larger in activated than in nonactivated cells. These results probably reflect that during the course of activation 1) the number of voltage-dependent K+ channels per cell decreases and increases in a small subset and 2) the number of Ca(2+)-dependent K+ channels per cell increases in all cells. We suggest that the expression of functional Ca(2+)- and voltage-activated K+ channels are under the control of different regulatory signals.
采用单通道和全细胞膜片钳记录技术，对人B淋巴细胞K⁺通道的表达及特性进行了研究。它们分别由去极化（电压门控钾电流，IKv，11 - 20 pS）和细胞内Ca²⁺浓度升高（钙激活钾电流，IKCa，26 pS）门控。这些通道的表达水平与细胞的激活状态相关。两种电导均被四乙铵、维拉帕米和蝎毒素阻断，对蜂毒明肽不敏感；4 - 氨基吡啶优先阻断IK。我们使用蛋白激酶C激活剂（PMA）或膜Ig抗体（抗μ）激活培养中的静息脾细胞。虽然在大多数静息淋巴细胞群体中记录到了IKv，但激活细胞中表达这种电导的不到20%。然而，在这个亚群中，IKv的幅度比静息细胞大20倍。另一方面，在近一半的静息细胞中检测到了IKCa，而所有激活细胞均表达这种电流。IKCa的幅度在激活细胞中平均比未激活细胞大30倍。这些结果可能反映出在激活过程中：1）每个细胞中电压依赖性K⁺通道的数量减少，在一小部分细胞中增加；2）每个细胞中钙依赖性K⁺通道的数量在所有细胞中增加。我们认为功能性钙激活和电压激活K⁺通道的表达受不同调节信号的控制。
