Owen N E, Villereal M L
Am J Physiol. 1985 Mar;248(3 Pt 1):C288-95. doi: 10.1152/ajpcell.1985.248.3.C288.
Previous studies in human foreskin fibroblasts suggested that the mechanism by which serum stimulates Na+ influx is via a Ca2+-calmodulin-mediated event. In the present experiments in normal WI-38 cells (human lung fibroblasts), both the intracellular Ca2+ antagonist 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8) and the potent calmodulin antagonist trifluoperazine (TFP) blocked serum-stimulated Na+ influx [TMB-8 concentration causing half-maximal inhibition (Ki) = 15 microM and TFP Ki = 10 microM]. Similar results were obtained in Swiss 3T3 cells. In contrast, in transformed WI-38 or Swiss 3T3 cells neither TMB-8 nor TFP had any effect on serum-stimulated Na+ influx (TMB-8 Ki greater than 100 microM and TFP Ki greater than 100 microM). In addition, when 45Ca2+ efflux measurements were made on normal and transformed cells, serum stimulated significant 45Ca2+ efflux (P less than 0.05) from WI-38 and Swiss 3T3 cells, while having no effect on 45Ca2+ efflux from simian virus 40 (SV40)-WI-38 or SV40-Swiss 3T3 cells. However, an elevation of intracellular Ca2+ can stimulate Na+ influx, since it was found that A23187 mimicked the effects of serum in both normal and transformed cells. These results suggest that the Ca2+-calmodulin-mediated event, which is thought to be involved in serum-stimulated Na+ influx in normal cells, may be bypassed or overridden in transformed cells.
先前在人包皮成纤维细胞中的研究表明，血清刺激钠离子内流的机制是通过钙调蛋白介导的事件。在目前对正常WI-38细胞（人肺成纤维细胞）进行的实验中，细胞内钙离子拮抗剂8-（N，N-二乙氨基）-辛基-3,4,5-三甲氧基苯甲酸酯（TMB-8）和强效钙调蛋白拮抗剂三氟拉嗪（TFP）均阻断了血清刺激的钠离子内流[TMB-8引起半数最大抑制的浓度（Ki）=15微摩尔，TFP的Ki=10微摩尔]。在瑞士3T3细胞中也得到了类似结果。相反，在转化的WI-38或瑞士3T3细胞中，TMB-8和TFP对血清刺激的钠离子内流均无任何作用（TMB-8的Ki大于100微摩尔，TFP的Ki大于100微摩尔）。此外，当对正常细胞和转化细胞进行45Ca2+外流测量时，血清刺激WI-38和瑞士3T3细胞出现显著的45Ca2+外流（P<0.05），而对猿猴病毒40（SV40）-WI-38或SV40-瑞士3T3细胞的45Ca2+外流无影响。然而，细胞内钙离子升高可刺激钠离子内流，因为发现A23187在正常细胞和转化细胞中均可模拟血清的作用。这些结果表明，在正常细胞中被认为参与血清刺激的钠离子内流的钙调蛋白介导事件，在转化细胞中可能被绕过或超越。
