Capsaicin-induced currents with distinct desensitization and Ca2+ dependence in rat trigeminal ganglion cells
Capsaicin-induced currents with distinct desensitization and Ca2+ dependence in rat trigeminal ganglion cells
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DOI：
10.1152/jn.1996.75.4.1503
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发表时间：
1996-04-01
影响因子：
2.5
通讯作者：
Simon, SA
中科院分区：
文献类型：
--
作者：
Liu, L;Simon, SA
1.全细胞膜片钳记录从培养的大鼠三叉神经节细胞具有索马直径范围从20到50 μ m，辣椒素激活两个内向电流和外向电流。在-60 mV时，内向电流可以通过其不同的峰值时间来区分，分别为4.2 +/- 3.1和41.4 +/- 16.4（SD）s。索马直径最小的细胞电流密度最大.更快的激活电流具有线性的电流-电压关系和接近0 mV的反转电位。激活较慢的电流不是Ca 2+激活的Cl-电流.快速电流（I-p）-辣椒碱浓度（C）关系的峰值特征为I-p/I-pmax = [1 +（C/K-d）（n）]（-1），其中n = 1.2，解离常数（K-d）= 0.68 μ M。快速激活电流在其激活速率和脱敏程度方面是不均匀的。在浸泡在含有钙的缓冲液中并保持在-60 mV的细胞中，大多数辣椒素激活的电流脱敏。去除细胞外Ca 2+可减轻、消除或不影响脱敏作用.在正保持电位下，电流非常缓慢地脱敏，即使在Ca 2+的存在下。重复30秒应用1 μ M辣椒素，间隔0.5，2.5和5.5分钟，所有诱导快速耐受。快速耐受性呈指数下降，直到电流保持近似恒定。减少辣椒素应用之间的时间增加了快速耐受的程度，而细胞外Ca 2+的消除显着降低快速耐受。
1. Whole cell patch-clamp records from cultured rat trigeminal ganglion cells having soma diameters ranging from 20 to 50 mu m revealed that capsaicin activated two inward currents and an outward current. At -60 mV, the inward currents could be distinguished by their different peak times, which were 4.2 +/- 3.1 and 41.4 +/- 16.4 (SD) s.2. Cells with the smallest soma diameters had the largest current densities.3. The more rapidly activating current had a linear current-voltage relation and a reversal potential near 0 mV.4. The more slowly activating current is not a Ca2+-activated Cl- current.5. The peak of the rapid current (I-p)-capsaicin concentration (C) relationship was characterized by I-p/I-pmax = [1 + (C/K-d)(n)](-1), where n = 1.2 and the dissociation constant (K-d) = 0.68 mu M.6. The rapidly activating current was heterogeneous in regards to both its rate of activation and extent of desensitization. In cells bathed in buffer containing calcium and held at -60 mV, most of the capsaicin-activated currents desensitized. Removal of extracellular Ca2+ could reduce, eliminate, or have no effect on desensitization.7. At positive holding potentials the currents very slowly desensitized, even in the presence of Ca2+.8. Repeated 30-s applications of 1 mu M capsaicin separated by 0.5, 2.5, and 5.5 min all induced tachyphylaxis. Tachyphylaxis decreased exponentially until the current remained approximately constant. Decreasing the time between capsaicin applications increased the extent of tachyphylaxis, whereas elimination of extracellular Ca2+ markedly reduced tachyphylaxis.