A nucleotide receptor in vascular endothelial cells is specifically activated by the fully ionized forms of ATP and UTP.
A nucleotide receptor in vascular endothelial cells is specifically activated by the fully ionized forms of ATP and UTP.
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血管内皮细胞中的核苷酸受体被完全电离形式的 ATP 和 UTP 特异性激活。
DOI：
10.1042/bj2840733
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Weisman,GA
中科院分区：
文献类型：
--
作者：
Lustig,KD;Sportiello,MG;Erb,L;Weisman,GA
细胞外ATP引起牛肺动脉内皮细胞（BPAE）细胞质游离钙（[Ca2+]i）浓度的增加，导致前列环素（PGI2）的合成和释放，PGI2是一种有效的血管舒张剂和血小板聚集抑制剂。我们在这里表明，PGI2在BPAE细胞中的释放与完全电离形式的细胞外ATP （ATP4-）的浓度相关，而与其他离子形式的ATP浓度无关。浓度低至10 nM-ATP4-引起PGI2释放增加[EC50 (concern)]。在pH 7.4、缺乏Ca2+和Mg2+的等渗培养基中培养的BPAE细胞。当改变培养基的pH或Mg2+浓度以维持ATP4-的恒定水平，同时改变质子atp （HATP3-）或MgATP2-的浓度时，PGI2的释放保持恒定。胞外Mg2+对PGI2释放的抑制作用可能完全归因于ATP4-浓度的降低。与Mg2+相反，细胞外Ca2+刺激ATP诱导的PGI2释放。一些结果表明，细胞外Ca2+通过ATP（4-）激活的质膜通道增加Ca2+摄取来调节PGI2的释放。在无Ca（2+）培养基中培养的BPAE细胞中，ATP引起了[Ca2+]i的短暂增加，并在60 s内下降到基础水平。在含有Ca（2+）的培养基中培养的细胞中，ATP引起[Ca2+]i的增加，其有两个组成部分：[Ca2+]i的短暂峰值（0-60 s）和[Ca2+]i的持续增加，并在ATP添加后维持几分钟。将细胞外钙浓度从0.25 mM增加到10 mM，对ATP诱导的[Ca2+]i的短暂升高没有影响，但显著增强了[Ca2+]i的持续升高幅度。[Ca2+]i持续增加幅度的改变可能会调节PGI2的释放，而PGI2的释放直到ATP加入后2分钟才完成。细胞外Ca2+也刺激缓激素诱导的PGI2释放。在细胞外Ca2+存在的情况下，缓激肽引起BPAE细胞中[Ca2+]i的持续增加。最后，UTP（一种比ATP更有效的激动剂）诱导的PGI2释放强度与细胞外完全电离的UTP （UTP4-）的浓度相关。这些发现支持了一种假设，即BPAE细胞中的核苷酸受体识别ATP和UTP的完全电离形式，并与涉及细胞内Ca2+的动员，细胞外Ca2+的内流和随后的PGI2释放的信号转导途径耦合。
Extracellular ATP causes an increase in the concentration of cytoplasmic free calcium ([Ca2+]i) in bovine pulmonary-artery endothelial (BPAE) cells that results in the synthesis and release of prostacyclin (PGI2), a potent vasodilator and inhibitor of platelet aggregation. We show here that PGI2 release in BPAE cells correlates with the concentration of the fully ionized form of extracellular ATP (ATP4-) and not with the concentration of other ionic forms of ATP. Concentrations as low as 10 nM-ATP4- elicited an increase in PGI2 release [EC50 (concn. giving half-maximal stimulation) 3 microM] in BPAE cells incubated in an iso-osmotic medium, pH 7.4, lacking Ca2+ and Mg2+. When the pH or the Mg2+ concentration of the medium was varied so as to maintain a constant level of ATP4-, while varying the concentration of proton-ATP (HATP3-) or MgATP2- respectively, PGI2 release remained constant. An inhibitory effect of extracellular Mg2+ on PGI2 release could be attributed solely to a decrease in the concentration of ATP4-. In contrast with Mg2+, extracellular Ca2+ stimulated PGI2 release induced by ATP. Several results suggest that extracellular Ca2+ modulates PGI2 release by increasing Ca2+ uptake through an ATP(4-)-activated plasma-membrane channel. In BPAE cells incubated in Ca(2+)-free medium, ATP elicited a transient increase in [Ca2+]i that declined to the basal level within 60 s. In cells incubated in Ca(2+)-containing medium, ATP caused an increase in [Ca2+]i that had two components: a transient peak in [Ca2+]i (0-60 s) and a sustained increase in [Ca2+]i that was maintained for several minutes after ATP addition. Increasing the concentration of extracellular calcium from 0.25 mM to 10 mM had no effect on the transient rise in [Ca2+]i induced by ATP, but significantly enhanced the magnitude of the sustained increase in [Ca2+]i. Alterations in the magnitude of the sustained increase in [Ca2+]i would likely modulate PGI2 release, which was not complete until 2 min after ATP addition. Extracellular Ca2+ also stimulated PGI2 release induced by bradykinin. Bradykinin caused a sustained increase in [Ca2+]i in BPAE cells in the presence of extracellular Ca2+. Finally, the magnitude of PGI2 release induced by UTP, a more potent agonist than ATP, correlated with the concentration of extracellular fully ionized UTP (UTP4-). These findings support the hypothesis that nucleotide receptors in BPAE cells recognize the fully ionized form of ATP and UTP and are coupled to signal-transduction pathways involving the mobilization of intracellular Ca2+, the influx of extracellular Ca2+ and the subsequent release of PGI2.