P2X2 receptors are essential for [Ca2+]i increases in response to ATP in cultured rat myenteric neurons.
P2X2 receptors are essential for [Ca2+]i increases in response to ATP in cultured rat myenteric neurons.
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DOI：
10.1152/ajpgi.00017.2005
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发表时间：
2005-05
期刊：
影响因子：
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通讯作者：
T. Ohta;Akane Kubota;M. Murakami;K. Otsuguro;S. Ito
中科院分区：
文献类型：
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作者：
T. Ohta;Akane Kubota;M. Murakami;K. Otsuguro;S. Ito
我们的特点是ATP诱导的细胞内Ca 2+浓度（[Ca 2 +]i）和膜电流的变化，在培养的大鼠肌间神经元使用比率Ca 2+成像与Fura-2和全细胞膜片钳技术，分别。神经元细胞功能鉴定的[Ca 2 +]i响应高K+和尼古丁，这只发生在神经元特异性蛋白基因产物9.5免疫反应阳性的细胞。ATP引起的[Ca ~（2+）]i的增加呈剂量依赖性，而细胞外Ca ~（2+）浓度（[Ca ~（2+）]o）的去除则使[Ca ~（2+）] i显著降低。电压依赖性钙通道阻滞剂的存在下，[Ca 2 +]i响应ATP的幅度减少了一半。在[Ca 2 +] o-自由的溶液中，ATP产生了一个小的瞬时升高[Ca 2 +]i类似于P2 Y激动剂诱导的。在-60 mV时，ATP诱发缓慢失活的内向电流，该电流被细胞外Na+浓度的去除所抑制。ATP的电流-电压关系为内向整流，其反向电位约为0 mV。嘌呤受体激动剂诱导的[Ca ~（2+）]i增加的效力的表观等级顺序为ATP >或=腺苷5 '-O-3-三磷酸>或= CTP >或= 2-甲硫基-ATP>苯甲酰苯甲酰-ATP。获得了类似的效力顺序与这些激动剂的电流响应。P2拮抗剂抑制ATP诱导的内向电流。Ca ~（2+）、Mg ~（2+）抑制ATP诱导的电流，Zn ~（2+）、Cu ~（2+）和质子增强ATP诱导的电流。提示ATP主要激活亲离子型P2 X2受体，导致大鼠肌间神经元内[Ca ~（2+）]i依赖于[Ca ~（2+）]o的增加。一小部分ATP诱导的[Ca ~（2+）]i增加也可能通过P_2Y受体相关机制介导。
We characterized ATP-induced changes in intracellular Ca2+ concentration ([Ca2+]i) and membrane current in cultured rat myenteric neurons using ratiometric Ca2+ imaging with fura-2 and the whole cell patch-clamp technique, respectively. Neuronal cells were functionally identified by [Ca2+]i responses to high K+ and nicotine, which occurred only in cells positive for neuron-specific protein gene product 9.5 immunoreactivity. ATP evoked a dose-dependent increase of [Ca2+]i that was greatly decreased by the removal of extracellular Ca2+ concentration ([Ca2+]o). The amplitude of the [Ca2+]i response to ATP was reduced by half in the presence of voltage-dependent Ca2+ channel blockers. In [Ca2+]o-free solution, ATP produced a small transient rise in [Ca2+]i similar to that induced by P2Y agonists. At -60 mV, ATP evoked a slowly inactivating inward current that was suppressed by the removal of extracellular Na+ concentration. The current-voltage relation for ATP showed an inward rectification with the reversal potential of about 0 mV. The apparent rank order of potency for the purinoceptor agonist-induced increases of [Ca2+]i was ATP > or = adenosine 5'-O-3-triphosphate > or = CTP > or = 2-methylthio-ATP > benzoylbenzoyl-ATP. A similar potency order was obtained with current responses to these agonists. P2 antagonists inhibited inward currents induced by ATP. Ca2+ and Mg2+ suppressed the ATP-induced current, and Zn2+, Cu2+, and protons potentiated it. RT-PCR and immunocytochemical studies showed the expression of P2X2 receptors in cultured rat myenteric neurons. These results suggest that ATP mainly activates ionotropic P2X2 receptors, resulting in a [Ca2+]i increase dependent on [Ca2+]o in rat myenteric neurons. A small part of the ATP-induced [Ca2+]i increase may be also mediated via a P2Y receptor-related mechanism.