Effects of calcium and sodium on ATP-induced vasopressin release from rat isolated neurohypophysial terminals.
Effects of calcium and sodium on ATP-induced vasopressin release from rat isolated neurohypophysial terminals.
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DOI：
10.1111/jne.12605
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发表时间：
2018-05-04
影响因子：
3.2
通讯作者：
Lemos JR
中科院分区：
文献类型：
--
作者：
Custer EE;Knott TK;Ortiz-Miranda S;Lemos JR
ATP受体（P2 X2、P2 X3、P2 X4和P2 X7）存在于神经垂体末端（NHT）。已知这些嘌呤能受体亚型具有阳离子选择性。在这里，我们证实，钠（Na+）和钙（Ca 2+）是渗透通过这些NHT嘌呤能受体，但在不同程度上（91%对9%，分别）。此外，细胞外钙抑制ATP电流的大小。因此，本研究的目的是确定细胞外Na+与Ca 2+对ATP诱导的加压素（AVP）释放的大鼠分离NHT群体的影响。在Normal Locke缓冲液中外源性灌注ATP（200 µM）2分钟，引起AVP释放的最初短暂增加，随后AVP释放持续增加，持续ATP暴露期间。用NMDG-Cl替代细胞外NaCl对ATP引起的AVP释放的短暂增加没有明显影响，但消除了ATP引起的持续AVP释放。此外，细胞外钙的去除导致没有ATP诱导的AVP释放的瞬时增加，但对延迟，持续增加AVP释放没有影响。10 µM P2 X嘌呤能受体拮抗剂PPADS（足以阻断P2 X2和P2 X3受体，但不阻断P2 X4或P2 X7受体）可抑制ATP诱导的AVP释放的钙依赖性瞬时增加>95%。有趣的是，ATP诱导的AVP释放的钙非依赖性、钠依赖性持续增加不受10 µM PPADS的影响。ATP诱导的AVP释放的钙依赖性瞬时增加不受P2 X7受体拮抗剂BBG（100 nM）的影响。而ATP诱导的钠依赖性AVP持续释放则被抑制50%。因此，这些结果表明，大鼠分离的NHT表现出对外源性ATP的双相反应，其差异依赖于细胞外钙和钠。此外，初始瞬时释放似乎是通过P2 X2和/或P2 X3受体，持续释放是通过P2 X7受体。
ATP-receptors (P2X2, P2X3, P2X4 & P2X7) are found in neurohypophysial terminals (NHT). These purinergic receptor subtypes are known to be cation selective. Here we confirm that both sodium (Na+) and calcium (Ca2+) are permeable through these NHT purinergic receptors, but to varying degrees (91% vs. 9%, respectively). Furthermore, extracellular calcium inhibits the ATP-current magnitude. Thus, the objective of this study was to determine the effects of extracellular Na+ vs. Ca2+ on ATP-induced vasopressin (AVP) release from populations of rat isolated NHT. ATP (200 µM) perfused exogenously for 2 minutes in Normal Locke’s buffer caused an initial transient increase in AVP release followed by a sustained increase in AVP release which lasted for the duration of the ATP exposure. Replacing extracellular NaCl with NMDG-Cl had no apparent effect on the ATP-induced transient increase in AVP release but abolished the sustained AVP release induced by ATP. Furthermore, removal of extracellular calcium resulted in no ATP-induced transient increase in AVP release, but had no effect on the delayed, sustained increase in AVP release. The ATP-induced calcium-dependent transient increase in AVP release was >95% inhibited by 10 µM of the P2X purinergic receptor antagonist PPADS, a dose sufficient to block P2X2 and P2X3 receptors but not P2X4 or P2X7 receptors. Interestingly, the ATP-induced calcium-independent, sodium-dependent sustained increase in AVP release was not affected by 10 µM PPADS. The ATP-induced calcium-dependent transient increase in AVP release was not affected by the P2X7 receptor antagonist BBG (100 nM). However, the ATP-induced sodium-dependent sustained AVP release was inhibited by 50%. Therefore, these results show that rat isolated NHT exhibit a biphasic response to exogenous ATP that is differentially dependent on extracellular calcium and sodium. Furthermore, the initial transient release appears to be through P2X2 and/or P2X3 receptors and the sustained release is through a P2X7 receptor.
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影响因子：
5.5
作者：
Troadec, JD;Thirion, S;Dayanithi, G
通讯作者：
Dayanithi, G
影响因子：
4.5
作者：
Knott, TK;Velázquez-Marrero, C;Lemos, JR
通讯作者：
Lemos, JR
影响因子：
5.5
作者：
Marrero, Hector G.;Lemos, Jose R.
通讯作者：
Lemos, Jose R.
DOI：
10.1073/pnas.93.5.1859
发表时间：
1996-03-05
影响因子：
11.1
作者：
Sun, XP;Stanley, EF
通讯作者：
Stanley, EF
影响因子：
3.2
作者：
Custer, E. E.;Knott, T. K.;Lemos, J. R.
通讯作者：
Lemos, J. R.