Yang C W, Borowitz J L, Gunasekar P G, Isom G E
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907-1334, USA.
J Biochem Toxicol. 1996;11(5):251-6. doi: 10.1002/(SICI)1522-7146(1996)11:5<251::AID-JBT6>3.0.CO;2-J.
Cyanide-induced neurotoxicity is associated with altered cellular Ca2+ homeostasis resulting in sustained elevation of cytosolic Ca2+. In order to characterize the effect of cyanide on intracellular signaling mechanisms, the interaction of KCN with the inositol 1,4,5-trisphosphate Ca2+ signaling system was determined in the PC12 cell line. KCN in the concentration range of 1.0-100 microM produced a rapid rise in intracellular IP3 levels (peak level occurred within 60 sec); 10 microM KCN elevated intracellular levels of IP3 to 148% of control levels. This response was mediated by phospholipase C (PLC) since U73122, a specific PLC inhibitor, blocked the response. Removal of Ca2+ from the incubation medium and chelation of intracellular Ca2+ with BAPTA partially attenuate the cyanide-stimulated IP3 generation, showing that the response is partially Ca2+ dependent. Also, treatment of cells with nifedipine or LaCl3, Ca2+ channel blockers, partially blocked the generation of IP3. This study shows that cyanide in concentrations as low as 1 microM stimulates IP3 generation that may be mediated by receptor and nonreceptor IP3 production since they have differential dependence on Ca2+. It is proposed that this response is an early intracellular signaling action that can contribute to altered Ca2+ homeostasis characteristic of cyanide neurotoxicity.
氰化物诱导的神经毒性与细胞内钙离子稳态改变有关，导致胞质钙离子持续升高。为了表征氰化物对细胞内信号传导机制的影响，在PC12细胞系中测定了氰化钾（KCN）与肌醇1,4,5-三磷酸（IP3）钙离子信号系统的相互作用。浓度范围为1.0 - 100微摩尔的KCN使细胞内IP3水平迅速升高（峰值在60秒内出现）；10微摩尔的KCN使细胞内IP3水平升高至对照水平的148%。这种反应由磷脂酶C（PLC）介导，因为特异性PLC抑制剂U73122可阻断该反应。从孵育培养基中去除钙离子以及用1,2-双（2-氨基苯氧基）乙烷-N,N,N',N'-四乙酸（BAPTA）螯合细胞内钙离子可部分减弱氰化物刺激的IP3生成，表明该反应部分依赖钙离子。此外，用钙离子通道阻滞剂硝苯地平或氯化镧处理细胞可部分阻断IP3的生成。本研究表明，低至1微摩尔浓度的氰化物可刺激IP3生成，这可能由受体和非受体IP3产生介导，因为它们对钙离子有不同的依赖性。有人提出，这种反应是一种早期细胞内信号传导作用，可能导致氰化物神经毒性所特有的钙离子稳态改变。
