Watano T, Kimura J
Department of Pharmacology, Fukushima Medical College, Japan.
Can J Cardiol. 1998 Feb;14(2):259-62.
The inhibitory effect of KB-R7943 (previously called No 7943) on the outward sodium-calcium exchange current was re-examined by applying the drug after inducing the outward exchange current rather than before the current onset as has been done previously. The outward exchange current was induced by raising the extracellular calcium ion concentration, [Ca2+]o, from 0.15 mM to 1.8 mM instead of from 0 mM to 1 mM, as has been done previously. Aftertreatment KB-R7943 inhibited the outward exchange current, and the concentration of KB-R7943 required to inhibit 50% of the exchange current [IC50] was approximately 3 microM. This value is 10 times higher than that obtained by pretreatment of the drug at 1 mM [Ca2+]o. The new IC50 of 3 microM is close to the values for the calcium current (8 microM) and the inward rectifier potassium current (7 microM) but is still significantly lower than that for the inward sodium-calcium exchange current (17 microM).
通过在诱导外向交换电流后而非如先前那样在电流开始前应用药物，重新研究了KB-R7943（先前称为7943号）对外向钠钙交换电流的抑制作用。外向交换电流通过将细胞外钙离子浓度[Ca2+]o从0.15 mM提高到1.8 mM来诱导，而不是如先前那样从0 mM提高到1 mM。给予KB-R7943后抑制了外向交换电流，抑制50%交换电流所需的KB-R7943浓度[IC50]约为3 microM。该值比在1 mM [Ca2+]o下进行药物预处理时获得的值高10倍。新的3 microM的IC50接近钙电流（8 microM）和内向整流钾电流（7 microM）的值，但仍显著低于内向钠钙交换电流（17 microM）的值。
