Experiments to test the role of phosphatidylinositol 4,5-bisphosphate in neurotransmitter-induced M-channel closure in bullfrog sympathetic neurons
Experiments to test the role of phosphatidylinositol 4,5-bisphosphate in neurotransmitter-induced M-channel closure in bullfrog sympathetic neurons
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DOI：
10.1523/jneurosci.23-12-04931.2003
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发表时间：
2003-06-15
影响因子：
5.3
通讯作者：
Smith, PA
中科院分区：
文献类型：
--
作者：
Ford, CP;Stemkowski, PL;Smith, PA
各种神经递质通过抑制一种普遍存在的、电压依赖的、非激活的K+电导来兴奋神经元，这种电导被称为M-电导(g(M))。在牛蛙交感神经节神经元中，P2Y激动剂三磷酸腺苷对g(M)的抑制涉及磷脂酶C(PLC)。这一结果与磷脂和肌醇磷酸循环参与了P2Y和M胆碱能激动剂对g(M)的影响是一致的。用磷脂酰肌醇4-激酶抑制剂Wortmannin(10微米)抑制磷脂酰肌醇4，5-二磷酸(PIP2)的再合成可减缓或阻断激动剂诱导的G_1抑制的恢复。这种作用不能归因于Wortmannin对肌球蛋白轻链激酶或磷脂酰肌醇3-激酶的作用。通过使用R59022(40微米)抑制二酰甘油激酶，在脂质循环的早期阶段抑制PIP2的合成也减缓了连续的ATP反应的恢复速度。这种作用需要多次应用激动剂来耗尽脂质循环中各种磷脂中间体的水平。PIP2抗体可减弱激动剂对G_1的抑制。细胞内应用20um的PIP2可减缓COS-1或TSA-201细胞表达的KCNQ2/3电流的下降，而100um的PIP2对牛蛙交感神经元的天然M电流有微弱的增强作用。如果激动剂诱导PLC的激活和伴随的PIP2的枯竭有助于神经递质的兴奋作用，从而抑制g，则这些结果是可以预期的。
Various neurotransmitters excite neurons by suppressing a ubiquitous, voltage-dependent, noninactivating K+ conductance called the M-conductance (g(M)). In bullfrog sympathetic ganglion neurons the suppression of g(M) by the P2Y agonist ATP involves phospholipase C (PLC). The present results are consistent with the involvement of the lipid and inositol phosphate cycles in the effects of both P2Y and muscarinic cholinergic agonists on g(M). Impairment of resynthesis of phosphatidylinositol 4,5-bisphosphate (PIP2) with the phosphatidylinositol 4-kinase inhibitor wortmannin (10 mum) slowed or blocked the recovery of agonist-induced g, suppression. This effect could not be attributed to an action of wortmannin on myosin light chain kinase or on phosphatidylinositol 3-kinase. Inhibition of PIP2 synthesis at an earlier point in the lipid cycle by the use of R59022 (40 mum) to inhibit diacylglycerol kinase also slowed the rate of recovery of successive ATP responses. This effect required several applications of agonist to deplete levels of various phospholipid intermediates in the lipid cycle. PIP2 antibodies attenuated the suppression of g, by agonists. Intracellular application of 20 muM PIP2 slowed the rundown of KCNQ2/3 currents expressed in COS-1 or tsA-201 cells, and 100 muM PIP2 produced a small potentiation of native M-current bullfrog sympathetic neurons. These are the results that might be expected if agonist-induced activation of PLC and the concomitant depletion of PIP2 contribute to the excitatory action of neurotransmitters that suppress g,.