J Physiol 367: 117-141
Potassium channels in cultured bovine adrenal chromaffin cells.
Abstract
K channels of bovine adrenal chromaffin cells were studied using patch-clamp techniques. Whole-cell K currents measured near +10 mV were much larger in 1 mM-external Ca than in Ca-free saline. Noise analysis suggested that this Ca-dependent current was carried by a large unitary conductance channel, called BK channel, which was previously described in inside-out patches (Marty, 1981). The Ca-dependent K current near +10 mV declined with time due to 'run-down' of Ca channels. At the same time, a fraction of the outward current observed above +50 mV was also eliminated. This outward current component probably represents K efflux through Ca channels. Whole-cell Ca-dependent K currents were studied using various Ca buffers. EGTA buffers were surprisingly inefficient: in order to block the current entirely, it was necessary to use an isotonic EGTA solution and to increase internal pH. 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was at least five times more efficient than EGTA. In isolated patches three types of single-channel K currents were observed. Under normal ionic conditions (140 mM-K inside, 140 mM-Na outside), the unitary conductances measured between -20 and +40 mV were 96 pS, 18 pS and 8 pS. The 96 pS channels are the Ca-dependent BK channels. 18 pS and 8 pS channels were both activated and then inactivated by membrane depolarization. Both displayed complex kinetics; single-channel currents were grouped in bursts. Activation and inactivation kinetics were faster for the 18 pS channel (therefore termed FK channel, for fast K channel) than for the 8 pS channel (SK channel, for slow or small amplitude channel). The voltage dependence of opening probability was steeper for the FK channel as compared to the SK channel.
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- Almers W, McCleskey EW. Non-selective conductance in calcium channels of frog muscle: calcium selectivity in a single-file pore. J Physiol. 1984 Aug;353:585–608.[PMC free article] [PubMed] [Google Scholar]
- Almers W, McCleskey EW, Palade PT. A non-selective cation conductance in frog muscle membrane blocked by micromolar external calcium ions. J Physiol. 1984 Aug;353:565–583.[PMC free article] [PubMed] [Google Scholar]
- Biales B, Dichter M, Tischler A. Electrical excitability of cultured adrenal chromaffin cells. J Physiol. 1976 Nov;262(3):743–753.[PMC free article] [PubMed] [Google Scholar]
- Brandt BL, Hagiwara S, Kidokoro Y, Miyazaki S. Action potentials in the rat chromaffin cell and effects of acetylcholine. J Physiol. 1976 Dec;263(3):417–439.[PMC free article] [PubMed] [Google Scholar]
- Cahalan MD, Chandy KG, DeCoursey TE, Gupta S. A voltage-gated potassium channel in human T lymphocytes. J Physiol. 1985 Jan;358:197–237.[PMC free article] [PubMed] [Google Scholar]
- Chad JE, Eckert R. Calcium domains associated with individual channels can account for anomalous voltage relations of CA-dependent responses. Biophys J. 1984 May;45(5):993–999.[PMC free article] [PubMed] [Google Scholar]
- Clapham DE, Neher E. Trifluoperazine reduces inward ionic currents and secretion by separate mechanisms in bovine chromaffin cells. J Physiol. 1984 Aug;353:541–564.[PMC free article] [PubMed] [Google Scholar]
- Conti F, Hille B, Nonner W. Non-stationary fluctuations of the potassium conductance at the node of ranvier of the frog. J Physiol. 1984 Aug;353:199–230.[PMC free article] [PubMed] [Google Scholar]
- Dubois JM. Potassium currents in the frog node of Ranvier. Prog Biophys Mol Biol. 1983;42(1):1–20. [PubMed] [Google Scholar]
- Fenwick EM, Marty A, Neher E. A patch-clamp study of bovine chromaffin cells and of their sensitivity to acetylcholine. J Physiol. 1982 Oct;331:577–597.[PMC free article] [PubMed] [Google Scholar]
- Fenwick EM, Marty A, Neher E. Sodium and calcium channels in bovine chromaffin cells. J Physiol. 1982 Oct;331:599–635.[PMC free article] [PubMed] [Google Scholar]
- Fernandez JM, Fox AP, Krasne S. Membrane patches and whole-cell membranes: a comparison of electrical properties in rat clonal pituitary (GH3) cells. J Physiol. 1984 Nov;356:565–585.[PMC free article] [PubMed] [Google Scholar]
- Fischmeister R, Horackova M. Variation of intracellular Ca2+ following Ca2+ current in heart. A theoretical study of ionic diffusion inside a cylindrical cell. Biophys J. 1983 Mar;41(3):341–348.[PMC free article] [PubMed] [Google Scholar]
- Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. [PubMed] [Google Scholar]
- Hermann A, Gorman AL. Action of quinidine on ionic currents of molluscan pacemaker neurons. J Gen Physiol. 1984 Jun;83(6):919–940.[PMC free article] [PubMed] [Google Scholar]
- Hermann A, Hartung K. Noise and relaxation measurements of the Ca2+ activated K+ current in Helix neurones. Pflugers Arch. 1982 May;393(3):254–261. [PubMed] [Google Scholar]
- Hermann A, Hartung K. Ca2+ activated K+ conductance in molluscan neurones. Cell Calcium. 1983 Dec;4(5-6):387–405. [PubMed] [Google Scholar]
- Hess P, Tsien RW. Mechanism of ion permeation through calcium channels. Nature. 309(5967):453–456. [PubMed] [Google Scholar]
- Heyer CB, Lux HD. Control of the delayed outward potassium currents in bursting pace-maker neurones of the snail, Helix pomatia. J Physiol. 1976 Nov;262(2):349–382.[PMC free article] [PubMed] [Google Scholar]
- Kidokoro Y, Ritchie AK. Chromaffin cell action potentials and their possible role in adrenaline secretion from rat adrenal medulla. J Physiol. 1980 Oct;307:199–216.[PMC free article] [PubMed] [Google Scholar]
- Kostyuk PG, Krishtal OA. Effects of calcium and calcium-chelating agents on the inward and outward current in the membrane of mollusc neurones. J Physiol. 1977 Sep;270(3):569–580.[PMC free article] [PubMed] [Google Scholar]
- Lee KS, Tsien RW. Reversal of current through calcium channels in dialysed single heart cells. Nature. 1982 Jun 10;297(5866):498–501. [PubMed] [Google Scholar]
- Lux HD, Neher E, Marty A. Single channel activity associated with the calcium dependent outward current in Helix pomatia. Pflugers Arch. 1981 Mar;389(3):293–295. [PubMed] [Google Scholar]
- Marty A. Ca-dependent K channels with large unitary conductance in chromaffin cell membranes. Nature. 1981 Jun 11;291(5815):497–500. [PubMed] [Google Scholar]
- Meech RW, Standen NB. Potassium activation in Helix aspersa neurones under voltage clamp: a component mediated by calcium influx. J Physiol. 1975 Jul;249(2):211–239.[PMC free article] [PubMed] [Google Scholar]
- Pennefather P, Lancaster B, Adams PR, Nicoll RA. Two distinct Ca-dependent K currents in bullfrog sympathetic ganglion cells. Proc Natl Acad Sci U S A. 1985 May;82(9):3040–3044.[PMC free article] [PubMed] [Google Scholar]
- Sigworth FJ. The variance of sodium current fluctuations at the node of Ranvier. J Physiol. 1980 Oct;307:97–129.[PMC free article] [PubMed] [Google Scholar]
- Tsien RY. New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures. Biochemistry. 1980 May 27;19(11):2396–2404. [PubMed] [Google Scholar]
- Ypey DL, Clapham DE. Development of a delayed outward-rectifying K+ conductance in cultured mouse peritoneal macrophages. Proc Natl Acad Sci U S A. 1984 May;81(10):3083–3087.[PMC free article] [PubMed] [Google Scholar]
- Zucker RS, Stockbridge N. Presynaptic calcium diffusion and the time courses of transmitter release and synaptic facilitation at the squid giant synapse. J Neurosci. 1983 Jun;3(6):1263–1269.[PMC free article] [PubMed] [Google Scholar]