Abstract
ATP-sensitive single-channel potassium currents were studied in the membrane of rat ventricular myocytes. With an internal K+ concentration of [K+]i=140 mM, the outwardly directed currents saturated at ∼1.8 pA in the region of positive potentials independently of the external K+ concentration [K+]o, whereas an increase in [K+]i of up to 300 mM caused a positive shift in the region of current saturation (from ∼+40 mV to ∼+100 mV) and an increase in the level of the saturation up to ∼4 pA. The openings of the channels appeared in bursts. Gating kinetics within the bursts were investigated. It was shown that the channel mean open (τo) and closed (τc) times during a burst depended primarily on the electromotive force (V-V k) for potassium ions. For different [K+]o, τo was maximal and τc was minimal in the region of reversal potentials (V rev); τo decreased and τc increased gradually with deviation ofV fromV rev. Therefore we conclude that the gating properties of the ATP-sensitive K channels depend on the ion flux parameters.
Similar content being viewed by others
References
Ascher P, Marty A, Neild TO (1978) Life time and elementary conductance of the channels mediating the excitatory effects of acetylcholine in Aplysia neurones. J Physiol 278:177–206
Bezanilla F, Armstrong CM (1972) Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid axons. J Gen Physiol 60:588–608
Binstock I, Lecar H (1969) Ammonium ion currents in the squid giant axon. J Gen Physiol 53:342–361
Burnashev N, Zilberter Yu (1986) Two types of single inward rectifying potassium channels in rat myocardial cells. Gen Physiol Biophys 5:495–504
Chandler WK, Meves H (1965) Voltage clamp experiments on internally perfused giant axons. J Gen Physiol 180:788–820
Chesnoy-Marchais D (1985) Kinetic properties and selectivity of calcium-permeable single channels in Aplysia neurones. J Physiol 367:457–488
Cohen-Armon M (1984) An ion-site interaction model for sodium currents in the giant axon. Biophys Chem 20:285–298
Colquhoun D, Sigworth F (1983) Fitting and statistical analysis of single-channels records. In: Sakmann B, Neher E (eds) Single channel recording. Plenum Press, New York, pp 191–263
Cukierman S, Yellen G, Miller C (1985) The K+ channel of sarcoplasmic reticulum, a new look at Cs+ block. Biophys J 48:477–484
Fishman HM, Poussart D, Leuchtag HR (1984) External potassium ion alter K channel kinetics in squid axon. Biophys J 45:141a
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100
Hodgkin AL, Huxley AF (1952) Currents carried by sodium and potassium ions through the membrane of the giant axon of Loligo. J Physiol 116:449–472
Horie M, Irisawa H, Noma A (1987) Voltage-dependent magnezium block of adenosine-triphosphate-sensitive potassium channel in guinea-pig ventricular cells. J Physiol 387:251–272
Kakei M, Noma A (1984) Adenosine-5′-triphosphate-sensitive single potassium channel in the atrioventricular node cell of the rabbit heart. J Physiol 352:265–284
Kameyama M, Kiyosue T, Soejima M (1983) Single channel analysis of the inward rectifier K+ current in the rabbit ventricular cells. Jpn J Physiol 33:1039–1056
Kurachi Y (1985) Voltage-dependent activation of the inward-rectifier potassium channel in the ventricular cell membrane of guinea-pig heart. J Physiol 366:365–385
Marchais D, Marty A (1979) Interaction of permeant ions with channels activated by acetylcholine in Aplysia neurones. J Physiol 297:9–45
Matteson DR, Swenson RP (1986) External monovalent cations that impede the closing of K channels. J Gen Physiol 87:795–816
Noma A (1983) ATP-regulated K+ channels in cardiac muscle. Nature 305:147–148
Noma A, Kakei M, Shibasaki T (1985) Adenosine-triphosphate-regulated potassium channels in guinea-pig ventricular cells. J Mol Cell Cardiol 17 (Suppl 1):31
Oxford GS, Yeh JZ (1985) Interaction of monovalent cations with sodium channels in squid axon. I. Modification of physiological inactivation gating. J Gen Physiol 85:583–602
Sakmann B, Trube G (1984) Conductance properties of single inwardly rectifying potassium channels in ventricular cells from guinea-pig heart. J Physiol 347:641–657
Stanfield PR, Ashcroft FM, Plant TD (1981) Gating of muscle K+ channel and its dependence on the permeating ion species. Nature 289:509–511
Swenson RP, Armstrong CM (1981) K+ channels close more slowly in the presence of external K+ and Rb+. Nature 291:427–429
Trube G, Hescheler J (1984) Inward-rectifying channels in isolated patches of the heart cell membrane: ATP-dependence and comparison with cell-attached patches. Pflügers Arch 401:178–184
Wittenberg BA, Robinson TF (1981) Oxigen requirements, morphology, cell coat and membrane permeability of calcium-tolerant myocytes from heart of adult rats. Cell Tissue Res 216:231–251
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zilberter, Y., Burnashev, N., Papin, A. et al. Gating kinetics of ATP-sensitive single potassium channels in myocardial cells depends on electromotive force. Pflugers Arch. 411, 584–589 (1988). https://doi.org/10.1007/BF00582382
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00582382