Bianchi L, Roy M L, Taglialatela M, Lundgren D W, Brown A M, Ficker E
Rammelkamp Center for Education and Research, Case Western Reserve University School of Medicine, Cleveland, Ohio 44109-1998, USA.
J Biol Chem. 1996 Mar 15;271(11):6114-21. doi: 10.1074/jbc.271.11.6114.
Polyamines have been shown to participate in the rectification of cloned inwardly rectifying potassium channels, a class of potassium channel proteins that conducts inward current more readily than outward current. Here, basophil leukemia cells were used to determine the effects of polyamines on a native, inwardly rectifying potassium current. Rat basophil leukemia cells were cultured in the presence of two different polyamine biosynthesis inhibitors, and both the electrophysiological properties and the polyamine levels were monitored. Treatment with alpha-difluoromethylornithine, a specific ornithine decarboxylase inhibitor, resulted in no significant change of electrophysiological properties. In contrast, treatment with 5'-[(Z)-4-amino-2-butenyl]- methyl-amino-5'-deoxyadenosine (MDL73811), an inhibitor of S-adenosylmethionine decarboxylase, resulted in increased outward currents through inwardly rectifying potassium channels while intracellular putrescine was markedly increased and spermidine and spermine levels were decreased. Fluctuations of intracellular polyamine concentrations as imposed by MDL73811 were directly translated in an altered cell excitability. Based on these results we conclude that the rectification properties of native inwardly rectifying potassium channels are largely controlled by intracellular spermine.
多胺已被证明参与克隆的内向整流钾通道的整流过程，内向整流钾通道是一类钾通道蛋白，其内向电流传导比外向电流更容易。在此，嗜碱性粒细胞白血病细胞被用于确定多胺对天然内向整流钾电流的影响。将大鼠嗜碱性粒细胞白血病细胞在两种不同的多胺生物合成抑制剂存在下培养，并监测其电生理特性和多胺水平。用α-二氟甲基鸟氨酸（一种特异性鸟氨酸脱羧酶抑制剂）处理，电生理特性无显著变化。相比之下，用S-腺苷甲硫氨酸脱羧酶抑制剂5'-[(Z)-4-氨基-2-丁烯基]-甲基氨基-5'-脱氧腺苷（MDL73811）处理，导致通过内向整流钾通道的外向电流增加，而细胞内腐胺明显增加，亚精胺和精胺水平降低。MDL73811引起的细胞内多胺浓度波动直接转化为细胞兴奋性的改变。基于这些结果，我们得出结论，天然内向整流钾通道的整流特性在很大程度上受细胞内精胺的控制。
