Fournier F, Honoré E, Collin T, Guilbault P
UFR de Biologie, Université des Sciences et Techniques de Lille-Flandres-Artois, Villeneuve d'Asq, France.
FEBS Lett. 1990 Dec 17;277(1-2):205-8. doi: 10.1016/0014-5793(90)80845-a.
In voltage-clamped Xenopus oocytes injected with embryonic guinea pig mRNA, effective concentrations of extracellular ATP elicited an inward fluctuating current. This current, carried by Cl-ions, was mainly dependent upon liberation of Ca2+ ions from stores as demonstrated by experiments using intracellular EGTA loading and TMB-8 superfusion. Neomycin inhibited these fluctuating currents indicating that the transplanted purinoceptor is linked to phospholipase C activity and triggers Ins(1,4,5)P3 formation. Ins(1,4,5)P3 production evoked by external ATP was clearly demonstrated by directly measuring the water-soluble Ins(1,4,5)P3 level in injected oocytes. Finally, it is suggested that the ATP effect was mediated by a Ca2+ release from Ins(1,4,5)P3 sensitive pools since heparin blocked the ATP responsiveness. The acquired purinoceptor may be made apparent to a P2 subtype since ATP and ADP were equipotent in eliciting Cl- current while AMP and Adenosine were ineffective in injected oocytes.
在注射了豚鼠胚胎mRNA的电压钳制非洲爪蟾卵母细胞中，有效浓度的细胞外ATP引发了内向波动电流。该电流由氯离子携带，如通过细胞内加载EGTA和灌注TMB - 8的实验所示，其主要依赖于从储存库中释放钙离子。新霉素抑制了这些波动电流，表明移植的嘌呤受体与磷脂酶C活性相关，并触发肌醇（1,4,5）三磷酸（Ins(1,4,5)P3）的形成。通过直接测量注射卵母细胞中的水溶性Ins(1,4,5)P3水平，清楚地证明了外部ATP诱发的Ins(1,4,5)P3产生。最后，由于肝素阻断了ATP反应性，提示ATP效应是由Ins(1,4,5)P3敏感池释放钙离子介导的。由于在注射的卵母细胞中ATP和ADP在引发氯离子电流方面等效，而AMP和腺苷无效，所获得的嘌呤受体可能属于P2亚型。
