ATP elicits inward currents in isolated vasopressinergic neurohypophysial terminals via P2X2 and P2X3 receptors
ATP elicits inward currents in isolated vasopressinergic neurohypophysial terminals via P2X2 and P2X3 receptors
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DOI：
10.1007/s00424-005-1471-x
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发表时间：
2005-09-01
影响因子：
4.5
通讯作者：
Lemos, JR
中科院分区：
文献类型：
--
作者：
Knott, TK;Velázquez-Marrero, C;Lemos, JR
在离体下丘脑神经垂体系统（HNS）末梢上，采用穿孔膜片全细胞记录技术，研究了细胞外三磷酸腺苷（ATP）对离子电流的影响。ATP在70%的这些隔离末端中诱导了电流反应。这种内向整流失活电流在0 mV附近有明显的逆转，并且对ATP呈剂量依赖性，EC 50 = 9.6 +/- 1.0 μ M。此外，在最大ATP浓度和最佳保持电位下测得的电流幅度为70.8 pA pF（-1），并被苏拉明和PPADS极大地抑制。测试了不同的嘌呤能受体激动剂，具有以下功效：ATP >= 2-甲硫基ATP> ATP-γ-S > Bz-Bz-ATP > α，β-亚甲基-ATP > β，γ-亚甲基-ATP。而UTP和ADP则无效。这些数据表明参与P2 X嘌呤能受体在ATP诱导的反应。加压素能末梢的免疫细胞化学标记表明存在P2 X（2，3.4）。(and 7），而不是P2 X（6）受体。此外，P2 X（2）（和3）在标记催产素的终末中未被发现。总之，EC 50、衰变、失活和药理学表明，P2 X（2和3）同型受体的功能混合物介导了加压素能HNS末端的大部分ATP反应。我们推测，这些类型的受体的特点反映了共同释放的ATP在这些和其他中枢神经系统神经元的终末室的功能。
Effects of extracellular adenosine tri-phosphate (ATP) on ionic currents were investigated using the perforated-patch whole-cell recording technique on isolated terminals of the Hypothalamic Neurohypophysial System (HNS). ATP induced a current response in 70% of these isolated terminals. This inwardly-rectifying, inactivating current had an apparent reversal near 0 mV and was dose-dependent on ATP with an EC50 = 9.6 +/- 1.0 mu M. In addition, current amplitudes measured at maximal ATP concentrations and optimum holding potentials had a current density of 70.8 pA pF(-1) and were greatly inhibited by suramin and PPADS. Different purinergic receptor agonists were tested, with the following efficacy: ATP >= 2-methylthioATP > ATP-gamma-S > Bz-Bz-ATP > alpha,beta-methylene-ATP > beta,gamma-methylene-ATP. However, UTP and ADP were ineffective. These data suggest the involvement of a P2X purinergic receptor in the ATP-induced responses. Immunocytochemical labeling in vasopressinergic terminals indicates the existence of P2X(2,3.4). (and 7,) but not P2X(6) receptors. Additionally, P2X(2) (and 3) were not found in terminals which labeled for oxytocin. In summary, the EC50, decay, inactivation, and pharmacology indicate that a functional mixture of P2X(2 and 3) homomeric receptors mediate the majority of the ATP responses in vasopressinergic HNS terminals. We speculate that the characteristics of these types of receptors reflect the function of co-released ATP in the terminal compartment of these and other CNS neurons.