title: The measurement of cardiac membrane channels following their incorporation into phospholipid bilayers.
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.
authors.forename: A J
authors.initials: AJ
authors.lastname: Williams
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004594:Electrophysiology; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008051:Lipid Bilayers; D009206:Myocardium / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012508:Sarcolemma / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000502:physiology
chemical_list: D002712:Chlorides; D007473:Ion Channels; D008051:Lipid Bilayers; D010743:Phospholipids; D011188:Potassium