Mironov S L
Max-Planck-Institute for Psychiatry, Planegg-Martinsried, Germany.
J Membr Biol. 1994 Sep;141(3):231-7. doi: 10.1007/BF00235132.
The effect of amidiniums on high-threshold Ca2+ channel currents (ICa) was studied in chick dorsal root ganglion neurons. Guanidinium reduced ICa in a dose-dependent fashion. The block was relieved by increasing the concentration of the permeant ions, Ba2+ or Ca2+, suggesting a competition for a common binding site within the channel. Formamidinium and methyl-guanidinium suppressed ICa with similar potencies, whereas L-arginine had no effect. A neutral amidine, urea, increased ICa. In Ca(2+)-free solutions guanidinium and Na+ permeated through the Ca2+ channel equally well. Structure-activity relationship obtained for blocking efficacies of different amidiniums are used to discuss possible configurations of the selectivity filter in the Ca2+ channel.
在鸡背根神经节神经元中研究了脒盐对高阈值Ca2+通道电流（ICa）的影响。胍盐以剂量依赖性方式降低ICa。通过增加通透离子Ba2+或Ca2+的浓度可解除这种阻断，这表明在通道内存在对共同结合位点的竞争。甲脒盐和甲基胍盐以相似的效力抑制ICa，而L-精氨酸则无作用。一种中性脒——尿素，可增加ICa。在无Ca(2+)的溶液中，胍盐和Na+通过Ca2+通道的通透情况相同。利用不同脒盐阻断效力得到的构效关系来讨论Ca2+通道中选择性过滤器的可能构型。
