Biomaterial Database

Permeability of time-dependent K+ channel in guinea pig ventricular myocytes to Cs+, Na+, NH4+, and Rb+. 1990

R W Hadley, and J R Hume

Department of Physiology, School of Medicine, University of Maryland, Baltimore 21201.

Currents through time-dependent K+ channels (also referred to as IK or the delayed rectifier) were studied with the whole cell patch-clamp technique in isolated guinea pig ventricular myocytes. IK measurements were restricted to the examination of deactivation tail currents. Substitution of various monovalent cations for external K+ produced shifts of the reversal potential of IK. These shifts were used to calculate permeability ratios relative to K+. The permeability sequence for the IK channels was K+ = Rb+ greater than NH4+ = Cs+ greater than Na+. Time-dependent outward currents were also examined when the myocytes were dialyzed with Cs+ instead of K+. A sizeable time-dependent outward current, quite similar to that seen with K+ dialysis, was demonstrated. This current was primarily carried by intracellular Cs+, as the reversal potential of the current shifted 46 mV per 10-fold change of external Cs+ concentration. The significance of Cs+ permeation through IK channels is discussed with respect to the common use of Cs+ in isolating other currents.

UI	MeSH Term	Description	Entries
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010539	Permeability	Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.	Permeabilities
D002414	Cations, Monovalent	Positively charged atoms, radicals or group of atoms with a valence of plus 1, which travel to the cathode or negative pole during electrolysis.	Monovalent Cation,Cation, Monovalent,Monovalent Cations
D002586	Cesium	A member of the alkali metals. It has an atomic symbol Cs, atomic number 55, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.	Caesium,Caesium-133,Cesium-133,Caesium 133,Cesium 133
D006168	Guinea Pigs	A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006352	Heart Ventricles	The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.	Cardiac Ventricle,Cardiac Ventricles,Heart Ventricle,Left Ventricle,Right Ventricle,Left Ventricles,Right Ventricles,Ventricle, Cardiac,Ventricle, Heart,Ventricle, Left,Ventricle, Right,Ventricles, Cardiac,Ventricles, Heart,Ventricles, Left,Ventricles, Right
D000641	Ammonia	A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012413	Rubidium	An element that is an alkali metal. It has an atomic symbol Rb, atomic number 37, and atomic weight 85.47. It is used as a chemical reagent and in the manufacture of photoelectric cells.
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23