Chen Z P, Levy A, McArdle C A, Lightman S L
Department of Medicine, University of Bristol, Bristol Royal Infirmary, UK.
Endocrinology. 1994 Sep;135(3):1280-3. doi: 10.1210/endo.135.3.8070374.
We have used real-time dynamic video imaging of Fura-2 fluorescence to study the acute effects of extracellular ATP on [Ca2+]i in pituitary cells and found that ATP produced a rapid biphasic cytosolic Ca2+ increase in a dose-dependent manner in both rat pituitary gonadotropes and gonadotrope-derived alpha T3-1 cells. Removal of extracellular Ca2+ only attenuated the plateau phase of ATP-induced intracellular Ca2+ response and suramin (100 microM), a P2-purinoceptor antagonist, reduced the ATP effect by 40-60%. Further studies revealed the following rank-order of agonist potency in the Ca2+ response: -ATP = ADP = UTP > 2-methylthioATP >> beta, gamma-methylene ATP/alpha,beta-methylene ATP. Both homologous and heterologous desensitization occurred with ATP and UTP and these did not have additive effects. Together the data suggest that the intracellular Ca2+ responses of gonadotropes and alpha T3-1 cells to these nucleotides are mediated by a single class of receptor pharmacologically characterized as the P2U subtype. This is the first demonstration of functional ATP receptors in pituitary gonadotropes.
我们利用Fura-2荧光实时动态视频成像技术研究了细胞外ATP对垂体细胞内钙离子浓度（[Ca2+]i）的急性影响，发现ATP能使大鼠垂体促性腺激素细胞和促性腺激素来源的αT3-1细胞的胞质钙离子迅速呈双相增加，且呈剂量依赖性。去除细胞外钙离子仅减弱了ATP诱导的细胞内钙离子反应的平台期，而P2嘌呤受体拮抗剂苏拉明（100微摩尔）使ATP的作用降低了40%-60%。进一步研究揭示了在钙离子反应中激动剂效力的以下排序：-ATP = ADP = UTP > 2-甲硫基ATP >> β,γ-亚甲基ATP/α,β-亚甲基ATP。ATP和UTP均出现同源和异源脱敏，且二者无相加作用。这些数据共同表明，促性腺激素细胞和αT3-1细胞对这些核苷酸产生的细胞内钙离子反应是由一类药理学上被鉴定为P2U亚型的受体介导的。这是垂体促性腺激素细胞中功能性ATP受体的首次证明。
