Gáspár R, Krasznai Z, Márián T, Trón L, Recchioni R, Falasca M, Moroni F, Pieri C, Damjanovich S
Department of Biophysics, University Medical School of Debrecen, Hungary.
Biochim Biophys Acta. 1992 Oct 27;1137(2):143-7. doi: 10.1016/0167-4889(92)90195-h.
Using the whole-cell variation of the patch-clamp technique it has been determined that 0.25-3 mM bretylium tosylate (BT) exerts a repolarizing effect on partially depolarized human lymphocytes. The repolarizing effect was ouabain (40 microM)-sensitive, and was inhibited by the removal of external Na+ or by the Na(+)-channel-blocker amiloride (10-44 microM), but K(+)-channel-blockers 4-aminopyridine (0.1-5 mM) and quinine (100 microM) had no effect. The drug induced a sodium dependent, amiloride-sensitive transient inward current reaching its maximum value approx. 20-30 s after the administration of BT and lasting for 6-10 min. This current was activated by depolarization within 25 ms at around -42 mV, its inactivation took about 2 s and its reversal potential was +24 +/- 5 mV. An increase in the intracellular sodium concentration (1.8-3.2 mM) has been observed upon the addition of BT by monitoring the SBFI fluorescence of the dye-loaded cells. It has been shown that whole-cell K+ currents are significantly decreased by BT. The existence of voltage and ligand (BT)-gated sodium channels has been postulated in human lymphocytes. These channels are thought to participate in the initiation of membrane repolarization in human lymphocytes, and thereby influence mitogenic or antigen-induced cell-activation processes.
运用膜片钳技术的全细胞变体，已确定0.25 - 3 mM的甲苯磺酸溴苄铵（BT）对部分去极化的人淋巴细胞具有复极化作用。该复极化作用对哇巴因（40 microM）敏感，并且通过去除细胞外Na⁺或使用Na⁺通道阻滞剂氨氯吡咪（10 - 44 microM）可被抑制，但K⁺通道阻滞剂4 - 氨基吡啶（0.1 - 5 mM）和奎宁（100 microM）没有作用。该药物诱导出一种钠依赖性、氨氯吡咪敏感的瞬时内向电流，在给予BT后约20 - 30秒达到最大值，并持续6 - 10分钟。此电流在约 - 42 mV时于25毫秒内被去极化激活，其失活约需2秒，其反转电位为 + 24 ± 5 mV。通过监测负载染料细胞的SBFI荧光，在添加BT后观察到细胞内钠浓度增加（1.8 - 3.2 mM）。已表明BT可显著降低全细胞K⁺电流。已推测人淋巴细胞中存在电压门控和配体（BT）门控的钠通道。这些通道被认为参与人淋巴细胞膜复极化的起始过程，从而影响有丝分裂或抗原诱导的细胞激活过程。
