Electropharmacological study of receptor-mediated regulation of cardiac Na^+-activated K^+ channels

受体介导的心脏Na^激活K^通道调节的电药理学研究

基本信息

批准号：
08670102
负责人：
NAKAYA Haruaki
金额：
$ 1.41万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08670102/
关键词：
Na^+-activated K^+ channel endothelin-1 beta_1-adrenoceptor ET_A receptor protein kinase A 心筋細胞 Na^+活性化 K^+チャネル ET_A エンドセリン β受容体

项目摘要

The Na<@D1+@>D1-activated K<@D1+@>D1 (K<@D2Na@>D2) channel has a large unitary conductance and is activated by an increase in the Na<@D1+@>D1 concentration at the inner side of the sarcolemma. It has been postulated that the K<@D2Na@>D2 channels may be activated not only in pathological conditions such as myocardial ischemia and digitalis toxicity but also in physiological conditions. However, it has not been determined whether cardiac K<@D2Na@>D2 channels are regulated by some receptor mechanisms. In this study I examined the effects of beta-adrenoceptor and endothelin (ET) receptor stimulation on the K<@D2Na@>D2 current in guinea pig ventricular cells by using patch clamp techniques. The K<@D2Na@>D2 current was activated by intracellular loading of 50 mM Na<@D1+@>D1 and extracellular application of 10 muM ouabain. Endothelin-1 (ET-1) at a concentration of 10 nM inhibited the K<@D2Na@>D2 current by 21(]SY.+-。[)4% (n=5), which was blocked by the selective ET<@D2A@>D2 receptor antagonis … More t BQ-485 (100 nM).Endothelin-3 (ET-3,30 nM) failed to inhibit the K<@D2Na@>D2 current. Neither protein kinase C inhibitor (staurosporine, calphostin C) nor intracellular loading of inositol 1,4,5-trisphosphate (IP<@D23@>D2) affected the K<@D2Na@>D2 current inhibition by ET-1. Isoproterenol (ISO,1-1000 nM) also inhibited the K<@D2Na@>D2 current in a concentration-dependent manner. The ISO (100 nM) -induced decrease of the K<@D2Na@>D2 current was abolished by 10 muM atenolol but not by 100 nM ICI 118,551, indicating the involvement of beta<@D21@>D2-adrenoceptors. Forskolin (10 muM) also inhibited the K<@D2Na@>D2 current and the ISO-induced K<@D2Na@>D2 current inhibition was attenuated by the intracellular loading of protein kinase inhibitor peptide. Therefore, cAMP-protein kinase A pathway plays an important role in the beta<@D21@>D2-adrenoceptor-mediated inhibition of the K<@D2Na@>D2 current. Thus, both ET<@D2A@>D2 receptor an beta<@D21@>D2-adrenoceptor stimulation inhibit the cardiac K<@D2Na@>D2 current and modulate the action potential repolarization in pathological as well as physiological conditions. Less

Na <@d1+@> D1激活的K <@D1+@> d1（k <@d2na@> d2）频道具有较大的单一电导率，并且由于Na <@d1+@> d1浓度的增加而被激活。据推测，K <@d2na@> D2通道不仅可以在病理状况（例如心肌缺血和digitalis毒性）中激活，而且在身体状况下也可以激活。但是，尚未确定心脏K <@d2na@> D2通道是否受某些受体机制调节。在这项研究中，我使用斑块夹技术研究了β-肾上腺素受体和内皮素（ET）受体刺激对豚鼠心室细胞中k <@d2na@> d2电流的影响。 k <@d2na@> d2电流通过50 mm Na <@d1+@> d1的细胞内加载和10个Mum Ouabain的细胞外应用激活。内皮素-1（ET-1）以10 nm的浓度抑制K <@d2na@> D2当前21（]SY。+ - 。[）4％（n = 5），被选择性ET <@d2a@> d2a@> d2a@> d2受体抗体所阻断，更多的t bq-485（100 nm）.endothelin-eendothelin-3（et-3,30 nm） k <@d2na@> d2电流。蛋白激酶C抑制剂（calosporine，calphostin c）均不影响1,4,5-三磷酸（IP <@d23@> d2）的细胞内负荷影响K <@d2na@> d2@> d2na@> d2 d2当前的ET-1抑制作用。异丙烯醇（ISO，1-1000 nm）也以浓度依赖性方式抑制K <@d2na@> d2电流。 ISO（100 nm）诱导的K <@d2na@> d2电流的降低被10个MUM ATELOL废除，但没有100 nm ICI 118,551，表明beta <@d21@> d21@> d2 -adrenocectors的参与。 Forskolin（10 MUM）还抑制了K <@D2NA@> D2电流，而ISO诱导的K <@D2NA@> D2电流抑制受到蛋白激酶抑制剂肽的细胞内负载的减弱。因此，cAMP蛋白激酶A途径在beta <@d21@> d2-adrenoceptor介导的k <@d2na@> d2电流中起着重要作用。这是ET <@d2a@> d2受体A beta <@d21@> d2-adrenoceptor刺激抑制心脏k <@d2na@> d2电流，并调节病理和生理条件中的动作电位重极化。较少的