HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Noble, D. Articles by Tsien, R. W. Search for Related Content PubMed PubMed Citation Articles by Noble, D. Articles by Tsien, R. W.

1. The membrane currents in Purkinje fibres under voltage clamp conditions have been investigated in the range of potentials at which the action potential plateau occurs. The results show that in this range slow outward current changes occur which are quite distinct from the potassium current activated in the pace-maker range of potentials.

2. The time course of current change in response to step voltage changes is non-exponential. At each potential the current changes may be analysed in terms of the sum of two exponential changes and this property has been used to dissect the currents into two components, i_x1 and i_x2, both of which have been found to obey kinetics of the Hodgkin—Huxley type.

3. The first component, i_x1, is activated with a time constant of about 0·5 sec at the plateau. At more positive and more negative potentials the time constants are shorter. The steady-state degree of activation varies from 0 at about -50 mV to about 1 at +20 mV. The instantaneous current—voltage relation is an inward-going rectifier but shows no detectable negative slope. In normal Tyrode solution ([K]₀ = 4 mM) the reversal potential is about -85 mV.

4. The second component, i_x2, is activated extremely slowly and the time constant at the plateau is about 4 sec. The steady-state activation curve varies from 0 at about -40 mV to 1 at about +20 mV. The instantaneous current—voltage relation is nearly linear. The reversal potential occurs between -50 and -20 mV in different preparations.

5. It is suggested that these currents are carried largely by K ions, but that some other ions (e.g. Na) also contribute so that the reversal potentials are positive to E_K.

6. The relation of these results to previous work on delayed rectification in cardiac muscle is discussed.

This article has been cited by other articles:

				D. M. Roden Repolarization Reserve: A Moving Target Circulation, September 2, 2008; 118(10): 981 - 982. [Full Text] [PDF]

				D. Noble From the Hodgkin-Huxley axon to the virtual heart J. Physiol., April 1, 2007; 580(1): 15 - 22. [Abstract] [Full Text] [PDF]

				D. M. Roden A New Role for Calmodulin in Ion Channel Biology Circ. Res., April 28, 2006; 98(8): 979 - 981. [Full Text] [PDF]

				J. M. Nerbonne and R. S. Kass Molecular Physiology of Cardiac Repolarization Physiol Rev, October 1, 2005; 85(4): 1205 - 1253. [Abstract] [Full Text] [PDF]

				Y. Shibukawa, E. L. Chilton, K. A. MacCannell, R. B. Clark, and W. R. Giles K+ Currents Activated by Depolarization in Cardiac Fibroblasts Biophys. J., June 1, 2005; 88(6): 3924 - 3935. [Abstract] [Full Text] [PDF]

				D. Noble Modeling the Heart Physiology, August 1, 2004; 19(4): 191 - 197. [Abstract] [Full Text] [PDF]

				H. Nakashima, U. Gerlach, D. Schmidt, and S. Nattel In vivo electrophysiological effects of a selective slow delayed-rectifier potassium channel blocker in anesthetized dogs: potential insights into class III actions Cardiovasc Res, March 1, 2004; 61(4): 705 - 714. [Abstract] [Full Text] [PDF]

				J. R. Ehrlich, M. Pourrier, M. Weerapura, N. Ethier, A. M. Marmabachi, T. E. Hebert, and S. Nattel KvLQT1 Modulates the Distribution and Biophysical Properties of HERG: A NOVEL {alpha}-SUBUNIT INTERACTION BETWEEN DELAYED RECTIFIER CURRENTS J. Biol. Chem., January 9, 2004; 279(2): 1233 - 1241. [Abstract] [Full Text] [PDF]

				N. lost, L. Virag, A. Varro, and J. Gy. Papp Comparison of the Effect of Class IA Antiarrhythmic Drugs on Transmembrane Potassium Currents in Rabbit Ventricular Myocytes Journal of Cardiovascular Pharmacology and Therapeutics, March 1, 2003; 8(1): 31 - 41. [Abstract] [PDF]

				J. Wang, K. Della Penna, H. Wang, J. Karczewski, T. M. Connolly, K. S. Koblan, P. B. Bennett, and J. J. Salata Functional and pharmacological properties of canine ERG potassium channels Am J Physiol Heart Circ Physiol, January 1, 2003; 284(1): H256 - H267. [Abstract] [Full Text] [PDF]

				W. Han, W. Bao, Z. Wang, and S. Nattel Comparison of Ion-Channel Subunit Expression in Canine Cardiac Purkinje Fibers and Ventricular Muscle Circ. Res., November 1, 2002; 91(9): 790 - 797. [Abstract] [Full Text] [PDF]

				M Malik, P Farbom, V Batchvarov, K Hnatkova, and A J Camm Relation between QT and RR intervals is highly individual among healthy subjects: implications for heart rate correction of the QT interval Heart, March 1, 2002; 87(3): 220 - 228. [Abstract] [Full Text] [PDF]

				T. Korte, M. Niehaus, G. Borchert, and J. Tebbenjohanns Significant prolongation of atrial monophasic action potential duration: short-term reverse electrophysiological changes after internal cardioversion of atrial fibrillation Cardiovasc Res, March 1, 2002; 53(4): 944 - 951. [Abstract] [Full Text] [PDF]

				W. Han, Z. Wang, and S. Nattel Slow delayed rectifier current and repolarization in canine cardiac Purkinje cells Am J Physiol Heart Circ Physiol, March 1, 2001; 280(3): H1075 - H1080. [Abstract] [Full Text] [PDF]

				L. Virag, N. Iost, M. Opincariu, J. Szolnoky, J. Szecsi, G. Bogats, P. Szenohradszky, A. Varro, and J. Gy. Papp The slow component of the delayed rectifier potassium current in undiseased human ventricular myocytes Cardiovasc Res, March 1, 2001; 49(4): 790 - 797. [Abstract] [Full Text] [PDF]

				Y. Tsuji, T. Opthof, K. Kamiya, K. Yasui, W. Liu, Z. Lu, and I. Kodama Pacing-induced heart failure causes a reduction of delayed rectifier potassium currents along with decreases in calcium and transient outward currents in rabbit ventricle Cardiovasc Res, November 1, 2000; 48(2): 300 - 309. [Abstract] [Full Text] [PDF]

				G.-R. Li, B. Yang, H. Sun, and C. M. Baumgarten Existence of a transient outward K+ current in guinea pig cardiac myocytes Am J Physiol Heart Circ Physiol, July 1, 2000; 279(1): H130 - H138. [Abstract] [Full Text] [PDF]

				L. Franqueza, M. Lin, I. Splawski, M. T. Keating, and M. C. Sanguinetti Long QT Syndrome-associated Mutations in the S4-S5 Linker of KvLQT1 Potassium Channels Modify Gating and Interaction with minK Subunits J. Biol. Chem., July 23, 1999; 274(30): 21063 - 21070. [Abstract] [Full Text] [PDF]

				A. Meir, S. Ginsburg, A. Butkevich, S. G. Kachalsky, I. Kaiserman, R. Ahdut, S. Demirgoren, and R. Rahamimoff Ion Channels in Presynaptic Nerve Terminals and Control of Transmitter Release Physiol Rev, July 1, 1999; 79(3): 1019 - 1088. [Abstract] [Full Text] [PDF]

				H. J. Granger Cardiovascular physiology in the twentieth century: great strides and missed opportunities Am J Physiol Heart Circ Physiol, December 1, 1998; 275(6): H1925 - H1936. [Abstract] [Full Text] [PDF]

				N. Iost, L. Virag, M. Opincariu, J. Szecsi, Andras Varro, and J. Gy. Papp Delayed rectifier potassium current in undiseased human ventricular myocytes Cardiovasc Res, December 1, 1998; 40(3): 508 - 515. [Abstract] [Full Text] [PDF]

				Y. Lu, L. Yue, Z. Wang, and S. Nattel Effects of the Diuretic Agent Indapamide on Na+, Transient Outward, and Delayed Rectifier Currents in Canine Atrial Myocytes Circ. Res., July 27, 1998; 83(2): 158 - 166. [Abstract] [Full Text] [PDF]

				G.-R. Li, H. Sun, and S. Nattel Characterization of a transient outward K+ current with inward rectification in canine ventricular myocytes Am J Physiol Cell Physiol, March 1, 1998; 274(3): C577 - C585. [Abstract] [Full Text] [PDF]

				R. S. Wymore, G. A. Gintant, R. T. Wymore, J. E. Dixon, D. McKinnon, and I. S. Cohen Tissue and Species Distribution of mRNA for the IKr-like K+ Channel, erg Circ. Res., February 1, 1997; 80(2): 261 - 268. [Abstract] [Full Text]

				E. G. Daoud, F. Bogun, R. Goyal, M. Harvey, K. C. Man, S. A. Strickberger, and F. Morady Effect of Atrial Fibrillation on Atrial Refractoriness in Humans Circulation, October 1, 1996; 94(7): 1600 - 1606. [Abstract] [Full Text]

				M.-L. Roy, R. Dumaine, and A. M. Brown HERG, a Primary Human Ventricular Target of the Nonsedating Antihistamine Terfenadine Circulation, August 15, 1996; 94(4): 817 - 823. [Abstract] [Full Text]

				L. Wang, Z.-P. Feng, C. S. Kondo, R. S. Sheldon, and H. J. Duff Developmental Changes in the Delayed Rectifier K+ Channels in Mouse Heart Circ. Res., July 1, 1996; 79(1): 79 - 85. [Abstract] [Full Text]

				G.-R. Li, J. Feng, Z. Wang, B. Fermini, and S. Nattel Adrenergic Modulation of Ultrarapid Delayed Rectifier K+ Current in Human Atrial Myocytes Circ. Res., May 1, 1996; 78(5): 903 - 915. [Abstract] [Full Text]

				G.-R. Li, J. Feng, L. Yue, M. Carrier, and S. Nattel Evidence for Two Components of Delayed Rectifier K+ Current in Human Ventricular Myocytes Circ. Res., April 1, 1996; 78(4): 689 - 696. [Abstract] [Full Text]

				M. W. Veldkamp, A. C.G. van Ginneken, T. Opthof, and L. N. Bouman Delayed Rectifier Channels in Human Ventricular Myocytes Circulation, December 15, 1995; 92(12): 3497 - 3504. [Abstract] [Full Text]

				T. Yang, S. Kupershmidt, and D. M. Roden Anti-minK Antisense Decreases the Amplitude of the Rapidly Activating Cardiac Delayed Rectifier K+ Current Circ. Res., December 1, 1995; 77(6): 1246 - 1253. [Abstract] [Full Text]

				D.-W. Liu and C. Antzelevitch Characteristics of the Delayed Rectifier Current (IKr and IKs) in Canine Ventricular Epicardial, Midmyocardial, and Endocardial Myocytes : A Weaker IKs Contributes to the Longer Action Potential of the M Cell Circ. Res., March 1, 1995; 76(3): 351 - 365. [Abstract] [Full Text]