{"title":"The measurement of cardiac membrane channels following their incorporation into phospholipid bilayers.","authors":"A J Williams","doi":"10.1007/978-1-4757-1287-2_5","DOIUrl":null,"url":null,"abstract":"<p><p>This chapter describes the basic properties of integral membrane channels from both cardiac sarcoplasmic reticulum and sarcolemma. Channels are studied, under voltage-clamp conditions, following their incorporation into planar phospholipid bilayers by fusion of isolated native membrane vesicles with preformed membranes. The rate of fusion of vesicles may be influenced by a number of factors including divalent cations and negatively charged phospholipids in the preformed bilayer. Mammalian cardiac sarcoplasmic reticulum contains a monovalent cation selective channel with a single-channel conductance of approximately 150 pico-Siemens in the presence of symmetrical solutions of 500 mM K+ at holding potentials ranging from -60 to +60 mV. The probability of the channel being in the open state is high at positive holding potentials and low at negative holding potentials. Mammalian cardiac sarcolemma contains at least three K+-selective channels and one Cl(-)-selective channel.</p>","PeriodicalId":77831,"journal":{"name":"Advances in myocardiology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1985-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advances in myocardiology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/978-1-4757-1287-2_5","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 2
Abstract
This chapter describes the basic properties of integral membrane channels from both cardiac sarcoplasmic reticulum and sarcolemma. Channels are studied, under voltage-clamp conditions, following their incorporation into planar phospholipid bilayers by fusion of isolated native membrane vesicles with preformed membranes. The rate of fusion of vesicles may be influenced by a number of factors including divalent cations and negatively charged phospholipids in the preformed bilayer. Mammalian cardiac sarcoplasmic reticulum contains a monovalent cation selective channel with a single-channel conductance of approximately 150 pico-Siemens in the presence of symmetrical solutions of 500 mM K+ at holding potentials ranging from -60 to +60 mV. The probability of the channel being in the open state is high at positive holding potentials and low at negative holding potentials. Mammalian cardiac sarcolemma contains at least three K+-selective channels and one Cl(-)-selective channel.
本章描述了来自心脏肌浆网和肌膜的整体膜通道的基本特性。在电压箝位条件下,通过分离的天然膜囊泡与预成型膜的融合,研究了通道与平面磷脂双层的融合。囊泡的融合速率可能受到许多因素的影响,包括预形成的双分子层中的二价阳离子和带负电荷的磷脂。哺乳动物心脏肌浆网含有一个单价阳离子选择通道,在500 mM K+的对称溶液存在下,其单通道电导约为150皮-西门子,保持电位范围为-60至+60 mV。通道处于开放状态的概率在正保持电位下高,在负保持电位下低。哺乳动物心脏肌膜包含至少3个K+选择性通道和1个Cl(-)选择性通道。