ROLE OF A T-TYPE CALCIUM CURRENT IN SUPPORTING A DEPOLARIZING POTENTIAL, DAMPED OSCILLATIONS, AND PHASIC FIRING IN VASOPRESSINERGIC GUINEA-PIG SUPRAOPTIC NEURONS
ROLE OF A T-TYPE CALCIUM CURRENT IN SUPPORTING A DEPOLARIZING POTENTIAL, DAMPED OSCILLATIONS, AND PHASIC FIRING IN VASOPRESSINERGIC GUINEA-PIG SUPRAOPTIC NEURONS
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DOI：
10.1159/000126438
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发表时间：
1993-05-01
影响因子：
4.1
通讯作者：
KELLY, MJ
中科院分区：
文献类型：
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作者：
ERICKSON, KR;RONNEKLEIV, OK;KELLY, MJ
用离体切片法对豚鼠视上核（SON）大细胞神经分泌细胞（MNCs）进行了研究。细胞内记录与biocytin填充电极，允许免疫细胞化学鉴定的记录细胞精氨酸加压素（AVP）与催产素（OT）的。只有显示去极化电位（DP）的AVP细胞才相位性放电。DP与电压钳中测量的瞬时内向电流相关，其表现出T型钙电流的许多特性：激活阈值为-64 mV，时程长达250 ms，镍阻断和氯化钡增强。这种电流以前在SON神经元中没有报道过。T型电流（I（T））总是与超极化步骤后的膜阻尼振荡有关。在所有测试的细胞中，观察到apamin敏感的后超极化（AHP），类似于大鼠SON和其他CNS区域中描述的钙依赖性钾电流（I（K，Ca））。因此，与显示阻尼振荡的其他CNS区域一样，豚鼠SON细胞具有I（T）和I（K，Ca）。我们先前已经描述了在这些细胞中在超极化电位下激活的I（h），其将膜去极化到I（T）和I（K，Ca）可以相互支持振荡的范围。总之，I（T）和相关的去极化电位似乎是豚鼠SON AVP细胞相位放电的必要特征。
Guinea pig magnocellular neurosecretory cells (MNCs) of the supraoptic nucleus (SON) were studied using the in vitro slice preparation. Intracellular recordings were made with biocytin-filled electrodes, permitting immunocytochemical identification of the recorded cells as arginine vasopressin- (AVP) versus oxytocin- (OT) containing. Only AVP cells displaying a depolarizing potential (DP) fired phasically. The DP was associated with a transient inward current measured in voltage clamp, which exhibited a number of properties of the T-type calcium current: activation threshold of -64 mV, time course of up to 250 ms, blockade by nickel and augmentation by barium chloride. This current has not been reported previously in SON neurons. The T-type current (I(T)) was always associated with a damped oscillation of the membrane following the offset from hyperpolarizing steps. In all cells tested, an apamin-sensitive afterhyperpolarization (AHP) was observed, similar to the calcium-dependent potassium current (I(K,Ca)) described in rat SON and other CNS regions. Therefore, as with other CNS regions displaying damped oscillations, guinea pig SON cells possess both an I(T) and an I(K,Ca). We have previously described an I(h) activating at hyperpolarized potentials in these cells, which depolarizes the membrane to a range in which the I(T) and I(K,Ca) can interactively support oscillations. In summary, the I(T) and associated depolarizing potential appears to be a requisite feature for phasic firing in AVP cells of guinea pig SON.