Characterization of exchange inhibitory peptide effects on Na+/Ca2+ exchange in rat and human brain plasma membrane vesicles.
Characterization of exchange inhibitory peptide effects on Na+/Ca2+ exchange in rat and human brain plasma membrane vesicles.
复制标题
交换抑制肽对大鼠和人脑质膜囊泡 Na /Ca2 交换影响的表征。
DOI：
10.1046/j.1471-4159.1994.63062136.x
复制
发表时间：
1994
影响因子：
4.7
通讯作者：
Colvin,RA
中科院分区：
文献类型：
--
作者：
Wu,A;Colvin,RA
Na+/Ca2+ 交换抑制肽 (XIP)（对应于犬心脏 Na+/Ca2+ 交换蛋白的残基 219-238）的抑制作用在大鼠和人脑质膜囊泡中进行了研究。 XIP 在抑制大鼠脑 [IC50= 3.05 ± 0.69 µM（平均值 ± SE）] 和人脑 (IC50= 3.58 ± 0.58 µM) 中囊泡内 Na+ 依赖性 Ca2+ 摄取的初始速度方面具有非常高的效力。大鼠脑囊泡的最大抑制率为 ∼80%，而人脑囊泡的抑制率为 100%。 XIP还抑制囊外Na+依赖性Ca2+释放，并且通过增加囊外Na+浓度来增强抑制作用。相反，贝普地尔的抑制作用相对于囊外Na+具有竞争性。当在稳态时（囊泡内 Na+ 依赖性 Ca2+ 摄取开始后 5 分钟）添加 XIP 时，发现囊内 Ca2+ 含量随时间下降。稳态 Ca2+ 单向通量分析表明，50 µMXIP 分别抑制 Ca2+ 流入和流出约 85% 和 70%。这一结果表明，XIP 抑制 Na+/Ca2+ 交换和 Ca2+/Ca2+ 交换，但对 Ca2+ 的被动释放途径没有影响。结果表明，心脏、大鼠和人脑交换器在 XIP 结合域中具有结构同源性，并且 XIP 需要结合 Na+ 或其他单价阳离子（例如 K+）才能对 Ca2+ 转运产生抑制作用。
The inhibitory effects of Na+/Ca2+exchange inhibitory peptide (XIP), which corresponds to residues 219–238 of the Na+/Ca2+exchange protein from canine heart, were studied in both rat and human brain plasma membrane vesicles. XIP had very high potency with respect to the inhibition of the initial velocity of intravesicular Na+‐dependent Ca2+uptake in both rat brain [IC50= 3.05 ± 0.69 µM(mean ± SE)] and human brain (IC50= 3.58 ± 0.58 µM). The maximal inhibition seen in rat brain vesicles was ∼80%, whereas human brain vesicles were inhibited 100%. XIP also inhibited extravesicular Na+‐dependent Ca2+release, and the inhibitory effect was enhanced by increasing the extravesicular Na+concentration. In contrast, the inhibitory effect of bepridil was competitive with respect to extravesicular Na+. When XIP was added at steady state (5 min after the initiation of intravesicular Na+‐dependent Ca2+uptake), it was found that the intravesicular Ca2+content declined with time. Analysis of unidirectional fluxes for Ca2+at steady state showed that 50 µMXIP inhibited Ca2+influx and efflux ∼85 and 70%, respectively. This result suggested that XIP inhibited both Na+/Ca2+exchange and Ca2+/Ca2+exchange but had no effect on the passive release pathway for Ca2+. The results suggest structural homology among cardiac, rat, and human brain exchangers in the XIP binding domain and that the binding of Na+or other monovalent cations, e.g., K+, is required for XIP to have its inhibitory effect on Ca2+transport.