Two types of potassium channels in murine T lymphocytes.
The properties of two types of K+ channels in murine T lymphocytes are described on the basis of whole-cell and isolated-patch recordings using the gigohm-seal technique. Type l (standing for "lpr gene locus" or "large") channels were characterized mainly in T cells from mutant MRL/MpJ-lpr/lpr mice, in which they are present in large numbers. Type n ("normal") K+ channels are abundant and therefore most readily studied in concanavalin A-activated T cells from four strains of mice, MRL-+/+, CBA/J, C57BL/6J, and BALB/c. Type l channels, compared with type n, are activated at potentials approximately 30 mV more positive, and close much more rapidly upon repolarization. Type l channels inactivate more slowly and less completely than type n during maintained depolarization, but recover from inactivation more rapidly, so that little inactivation accumulates during repetitive pulses. Type l channels have a higher unitary conductance (21 pS) than type n (12 pS) and are less sensitive to block by external Co++, but are 100-fold more sensitive to block by external tetraethylammonium (TEA), with half-block of type l channels at 50-100 microM TEA compared with 8-16 mM for type n. TEA blocks both types of channels by reducing the apparent single channel current amplitude, with a dose-response relation similar to that for blocking macroscopic currents. Murine type n K+ channels resemble K+ channels in human T cells.
D000818:Animals; D002412:Cations / Q000494:pharmacology; D003208:Concanavalin A / Q000494:pharmacology; D004553:Electric Conductivity; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008180:Lupus Erythematosus, Systemic / Q000503:physiopathology; D008564:Membrane Potentials; D051379:Mice; D008815:Mice, Inbred Strains; D008817:Mice, Mutant Strains; D013601:T-Lymphocytes / Q000502:physiology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D002412:Cations; D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D003208:Concanavalin A