Distribution of voltage-dependent and intracellular Ca2+ channels in submucosal neurons from rat distal colon
Distribution of voltage-dependent and intracellular Ca2+ channels in submucosal neurons from rat distal colon
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DOI：
10.1007/s00441-013-1643-5
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发表时间：
2013-09-01
影响因子：
3.6
通讯作者：
Diener, Martin
中科院分区：
文献类型：
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作者：
Rehn, Matthias;Bader, Sandra;Diener, Martin
我们最近观察到缓激肽引起的大鼠结肠粘膜下神经元胞浆内钙离子浓度的增加，这种增加可以被电压依赖性钙通道阻滞剂所抑制。由于肠道神经系统的这一部分所使用的钙-v通道的类型尚不清楚，因此用免疫组织化学方法研究了各种钙-v亚基在整装粘膜下层标本中的表达。粘膜下神经元由神经元标记物(微管相关蛋白2)识别，Ca(V)1.2、Ca(V)1.3和Ca(V)2.2免疫反应阳性，逆转录和聚合酶链式反应证实其表达。这些数据与以前的观察结果一致，即L和N型钙电流的抑制强烈地抑制了对缓激肽的反应。然而，全细胞膜片钳实验表明，缓激肽在电压钳条件下并不增强钙内流。因此，缓激肽并不直接与钙-v通道相互作用。相反，激动素诱导的钙内流是由激肽引起的膜去极化间接引起的。由于钙储存细胞器上的细胞内钙通道也参与了钙信号转导，其表达已被成像实验和免疫组织化学研究。肌醇1，4，5-三磷酸(IP3)受体(IP3R)已在含有钙敏感荧光染料Fura-2的粘膜下神经元上得到功能性证实。组胺是一种典型的与磷脂酶C途径偶联的激动剂，可诱导Fura-2信号比增加，该信号比可被IP3受体阻断剂2-氨基苯基硼酸酯抑制。免疫组织化学证实IP(3)R1的表达。相反，在很大的浓度范围内，兰诺定没有引起胞浆钙浓度的增加，也没有免疫组织化学证据表明兰诺定受体在这些神经元中的表达。因此，大鼠粘膜下神经元具有各种类型的高电压激活的钙-v通道和IP3受体，用于细胞内钙信号转导。
We recently observed a bradykinin-induced increase in the cytosolic Ca2+ concentration in submucosal neurons of rat colon, an increase inhibited by blockers of voltage-dependent Ca2+ (Ca-v) channels. As the types of Ca-v channels used by this part of the enteric nervous system are unknown, the expression of various Ca-v subunits has been investigated in whole-mount submucosal preparations by immunohistochemistry. Submucosal neurons, identified by a neuronal marker (microtubule-associated protein 2), are immunoreactive for Ca(v)1.2, Ca(v)1.3 and Ca(v)2.2, expression being confirmed by reverse transcription plus the polymerase chain reaction. These data agree with previous observations that the inhibition of L- and N-type Ca2+ currents strongly inhibits the response to bradykinin. However, whole-cell patch-clamp experiments have revealed that bradykinin does not enhance Ca2+ inward currents under voltage-clamp conditions. Consequently, bradykinin does not directly interact with Ca-v channels. Instead, the kinin-induced Ca2+ influx is caused indirectly by the membrane depolarization evoked by this peptide. As intracellular Ca2+ channels on Ca2+-storing organelles can also contribute to Ca2+ signaling, their expression has been investigated by imaging experiments and immunohistochemistry. Inositol 1,4,5-trisphosphate (IP3) receptors (IP3R) have been functionally demonstrated in submucosal neurons loaded with the Ca2+-sensitive fluorescent dye, fura-2. Histamine, a typical agonist coupled to the phospholipase C pathway, induces an increase in the fura-2 signal ratio, which is suppressed by 2-aminophenylborate, a blocker of IP3 receptors. The expression of IP(3)R1 has been confirmed by immunohistochemistry. In contrast, ryanodine, tested over a wide concentration range, evokes no increase in the cytosolic Ca2+ concentration nor is there immunohistochemical evidence for the expression of ryanodine receptors in these neurons. Thus, rat submucosal neurons are equipped with various types of high-voltage activated Ca-v channels and with IP3 receptors for intracellular Ca2+ signaling.