Department of Physiology, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan.
J Physiol Sci. 2010 Nov;60(6):415-24. doi: 10.1007/s12576-010-0113-z. Epub 2010 Sep 23.
Na(+)-dependent Mg(2+) efflux activity was studied with the fluorescent Mg(2+) indicator furaptra in the presence of various potential antagonists known to inhibit other transporters and channels. Among the compounds tested, KB-R7943, an inhibitor of Na(+)/Ca(2+) exchange, most potently inhibited the Na(+)/Mg(2+) exchange with half inhibitory concentrations (IC(50)) of 21 μM: (25°C) and 16 μM: (35°C). These IC(50) values were a factor of three to four lower than those of imipramine, a widely used inhibitor of Na(+)/Mg(2+) exchange. Apart from the inhibitory effect on Na(+)/Mg(2+) exchange, relatively high concentrations of KB-R7943 (100 μM: at 25°C and ≥20 μM: at 35°C), in combination with prolonged UV-illumination, caused cell shortening, probably because of the phototoxicity of the compound and the formation of rigor crossbridges. We conclude that KB-R7943 may be a useful tool to study cellular Mg(2+) homeostasis if care is taken to minimize its phototoxicity.
研究了在存在已知抑制其他转运体和通道的各种潜在拮抗剂的情况下，用荧光镁指示剂 furaptra 研究依赖 Na(+)的 Mg(2+)外排活性。在所测试的化合物中，Na(+)/Ca(2+)交换抑制剂 KB-R7943 最有效地抑制 Na(+)/Mg(2+)交换，其半抑制浓度 (IC50) 为 21 μM：（25°C）和 16 μM：（35°C）。这些 IC50 值比广泛用于抑制 Na(+)/Mg(2+)交换的丙咪嗪低三到四倍。除了对 Na(+)/Mg(2+)交换的抑制作用外，相对高浓度的 KB-R7943（在 25°C 下为 100 μM：和在 35°C 下为≥20 μM），与长时间的紫外线照射相结合，导致细胞缩短，可能是由于该化合物的光毒性和形成僵硬的交联桥。我们得出结论，如果注意将其光毒性降至最低，KB-R7943 可能是研究细胞镁 (2+)稳态的有用工具。
