Cattaneo M G, Magrini L, Sparber S B, Vicentini L M
Department of Pharmacology, University of Milan, Italy.
Cell Calcium. 1992 Nov;13(10):603-14. doi: 10.1016/0143-4160(92)90071-y.
A comparison of the effect of platelet-derived growth factor (PDGF) and bombesin on intracellular Ca2+ stores was carried out in Swiss 3T3 cells loaded with Fura-2. It was found that the tumor promoter thapsigargin (Tg) almost completely inhibited both the PDGF- and the bombesin-induced intracellular Ca2+ concentration ([Ca2+]i) rise, indicating that the two mitogens mobilize Ca2+ from intracellular pool(s) sensitive to the tumor promoter. It was also found that pre-treatment with PDGF almost totally and persistently (up to at least 30 min) inhibited the bombesin-, Tg- and ionomycin-induced rise in [Ca2+]i, whereas pre-treatment with bombesin had only a partial inhibitory effect on the PDGF, Tg and ionomycin [Ca2+]i response, both in the absence and in the presence of external Ca2+. On the other hand, vasopressin and bradykinin, which also stimulate hydrolysis of phosphoinositides in these cells, did not affect the [Ca2+]i response induced by the same agents. These results indicate that, despite the poor production of inositol 1,4,5-trisphosphate (InsP3), PDGF was capable of totally discharging and maintaining discharged the InsP3-sensitive stores of intracellular Ca2+, regardless of whether extracellular Ca2+ was present in the medium. Bombesin only partially caused this effect. On the contrary, bradykinin and vasopressin, after releasing intracellular Ca2+ allowed an almost total refilling of the pools. It is interesting to note that, at variance with PDGF and bombesin, neither bradykinin nor vasopressin are able to induce a mitogenic response in Swiss 3T3 cells.
在加载了Fura-2的瑞士3T3细胞中，对血小板衍生生长因子（PDGF）和蛙皮素对细胞内Ca2+储存的影响进行了比较。结果发现，肿瘤启动子毒胡萝卜素（Tg）几乎完全抑制了PDGF和蛙皮素诱导的细胞内Ca2+浓度（[Ca2+]i）升高，这表明这两种促有丝分裂原从对肿瘤启动子敏感的细胞内池动员Ca2+。还发现，用PDGF预处理几乎完全且持续地（至少持续30分钟）抑制了蛙皮素、Tg和离子霉素诱导的[Ca2+]i升高，而用蛙皮素预处理对PDGF、Tg和离子霉素的[Ca2+]i反应仅具有部分抑制作用，无论有无细胞外Ca2+。另一方面，血管加压素和缓激肽，它们也刺激这些细胞中磷酸肌醇的水解，但不影响相同试剂诱导的[Ca2+]i反应。这些结果表明，尽管肌醇1,4,5-三磷酸（InsP3）产生较少，但PDGF能够完全排空并维持细胞内Ca2+的InsP3敏感储存库排空，无论培养基中是否存在细胞外Ca2+。蛙皮素仅部分导致这种效应。相反，缓激肽和血管加压素在释放细胞内Ca2+后，几乎完全使储存库重新充满。有趣的是，与PDGF和蛙皮素不同，缓激肽和血管加压素都不能在瑞士3T3细胞中诱导促有丝分裂反应。
