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Molecular and Applied Pharmacology of Subunits of Ion Channels as Biosensors

作为生物传感器的离子通道亚基的分子和应用药理学

基本信息

批准号：
10559002
负责人：
YANAGISAWA Teruyuki
金额：
$ 8.38万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

N-type inactivation of rat Kv1.4 channels with one, two, or four inactivation balls was investigated using homogeneous populations of channels expressed in Xenopus oocytes. Tandem dimeric and tetrameric constructs of Kv1.4 were made. Channels encoded by tandem cDNAs Kv1.4-Kv1.4Delta1-145 and Kv1.4-[Kv1.4Delta1-145] (3) have two or only one tethered inactivation ball, respectively, whereas Kv1.4 itself encodes channels having four inactivation balls. The time constants for inactivation of macroscopic currents were increased significantly as the number of inactivation balls was decreased, whereas the time constants for recovery from inactivation were not modified. The ratios of the rate constants of inactivation (k (inact) ) of Kv1.4-Kv1.4Delta1-145 and Kv1.4-[Kv1.4Delta1-145] (3) channels to that of the Kv1.4 channel were 0.65 and 0.4, respectively, whereas the ratios of the rate constant of recovery (k (rec) ) of these channels to that of Kv1.4 were almost unity. The rate constants k ( … More inact) for channels having two and four inactivation balls are smaller than those that would be expected if inactivation balls on each channel are independent, suggesting some interaction occurs between inactivation balls. Furthermore, noninactivating current became apparent as the number of inactivation balls on a channel was decreased.Voltage-dependent calcium channels are crucially important for calcitum influx and following smooth muscle contraction. Beta subunits of these channels are known to modify calcium currerns through pore-forming alfa1 subunits. Among four reported independent beta subunit, the beta3 subunit in cardiovascular system, we have analyzed beta3-null mice. Electrophysiological examinations proved the existence of dihydropyridine (DHP)-sensitive, L-type calcium channels in the smooth muscle cell. Beta3-null mice show no apparent changes in smooth muscle contraction and sensitivity to DHP, and normal blood pressure when they are raised on a normal diet, but the beta3 subunit deficient mice show elevated blood pressure in response to a high-salt diet, with significant reductions in plasma catecholamine concentration. Our finding strongly suggests the adaptation to the null mutation of calcium channel beta subunit results in salt-sensitive hypertension. Less

使用爪蟾卵母细胞中表达的同质通道群研究了具有 1 个、2 个或 4 个失活球的大鼠 Kv1.4 通道的 N 型失活。制备了 Kv1.4 的串联二聚体和四聚体构建体。由串联 cDNA Kv1.4-Kv1.4Delta1-145 和 Kv1.4-[Kv1.4Delta1-145] (3) 编码的通道分别具有两个或仅一个拴系失活球，而 Kv1.4 本身编码具有四个失活球的通道。随着失活球数量的减少，宏观电流失活的时间常数显着增加，而从失活恢复的时间常数没有改变。 Kv1.4-Kv1.4Delta1-145和Kv1.4-[Kv1.4Delta1-145](3)通道的失活速率常数(k(inact))与Kv1.4通道的比率分别为0.65和0.4，而这些通道的恢复速率常数(k(rec))与Kv1.4的比率几乎为0.65和0.4。团结。具有两个和四个失活球的通道的速率常数 k（……更多不活动）小于每个通道上的失活球独立时预期的速率常数 k（... 更多不活动），这表明失活球之间发生了一些相互作用。此外，随着通道上失活球数量的减少，非失活电流变得明显。电压依赖性钙通道对于钙流入和平滑肌收缩至关重要。已知这些通道的β亚基可通过成孔的alfa1亚基改变钙电流。在四个报道的独立β亚基（心血管系统中的β3亚基）中，我们分析了β3缺失小鼠。电生理检查证明平滑肌细胞中存在二氢吡啶（DHP）敏感的L型钙通道。当正常饮食升高时，β3缺失小鼠的平滑肌收缩和对DHP的敏感性没有明显变化，血压也正常，但β3亚基缺陷小鼠在高盐饮食下表现出血压升高，血浆儿茶酚胺浓度显着降低。我们的发现强烈表明对钙通道β亚基无效突变的适应会导致盐敏感性高血压。较少的