© 2000 by European Society of Cardiology
Copyright © 2000, European Society of Cardiology
Characterisation of the transient outward K+ current in rabbit sinoatrial node cells
aSchool of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
bResearch Institute of Environmental Medicine, Nagoya University, Nagoya 464-01, Japan
* Corresponding author. Tel.: +44-113-233-4298; fax: +44-113-233-4224 m.r.boyett{at}leeds.ac.uk
Objective: To (i) characterise the electrophysiological and pharmacological properties of the transient outward K+ current, Ito, (ii) determine the relationship between the density of Ito and cell size, and (iii) determine the role of Ito in electrical activity in rabbit sinoatrial node cells at 35°C. Methods: Rabbit sinoatrial node cells were studied using whole-cell voltage and current clamp techniques. Results: Ito showed half activation and inactivation at +11 and –49 mV, respectively. Ito was blocked by 4-aminopyridine (4-AP) as well as the class I agents, quinidine and flecainide, with EC50 values of 326, 21, and 19 µM, respectively. The densities of the transient and sustained components of 4-AP-sensitive current were significantly correlated with cell capacitance, a measure of cell size, and were greater in cells with a larger capacitance. Block of Ito by 4-AP affected both the action potential and pacemaker activity of sinoatrial node cells and the effects were greater in cells with a larger capacitance. Conclusions: Ito in sinoatrial node cells shows similar electrophysiological and pharmacological properties to Ito in atrial and ventricular cells. The expression of Ito in sinoatrial node cells is heterogeneous and differs in large and small cells (likely to be from the periphery and centre of the sinoatrial node, respectively). Ito plays an important role in action potential configuration and pacemaker activity in sinoatrial node cells, especially in larger cells.
KEYWORDS K+ channels; Sinus nodes
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. E. Mangoni and J. Nargeot Genesis and Regulation of the Heart Automaticity Physiol Rev, July 1, 2008; 88(3): 919 - 982. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. Jones, M. Yamamoto, J. O. Tellez, R. Billeter, M. R. Boyett, H. Honjo, and M. K. Lancaster Distinguishing Properties of Cells From the Myocardial Sleeves of the Pulmonary Veins: A Comparison of Normal and Abnormal Pacemakers Circ Arrhythm Electrophysiol, April 1, 2008; 1(1): 39 - 48. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M.R. Boyett, H. Honjo, I. Kodama, M.K. Lancaster, M. Lei, H. Musa, and H. Zhang The Sinoatrial Node: Cell Size Does Matter Circ. Res., September 28, 2007; 101(7): e81 - e82. [Full Text] [PDF]
|
|
|
|
 |
|
 K. S. Stokoe, R. Balasubramaniam, C. A. Goddard, W. H. Colledge, A. A. Grace, and C. L.-H. Huang Effects of flecainide and quinidine on arrhythmogenic properties of Scn5a+/ murine hearts modelling the Brugada syndrome J. Physiol., May 15, 2007; 581(1): 255 - 275. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. O. Tellez, H. Dobrzynski, I. D. Greener, G. M. Graham, E. Laing, H. Honjo, S. J. Hubbard, M. R. Boyett, and R. Billeter Differential Expression of Ion Channel Transcripts in Atrial Muscle and Sinoatrial Node in Rabbit Circ. Res., December 8, 2006; 99(12): 1384 - 1393. [Abstract] [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]
|
|
|
|
|
|
M. Lei, C. Goddard, J. Liu, A.-L. Leoni, A. Royer, S. S.-M. Fung, G. Xiao, A. Ma, H. Zhang, F. Charpentier, et al. Sinus node dysfunction following targeted disruption of the murine cardiac sodium channel gene Scn5a J. Physiol., September 1, 2005; 567(2): 387 - 400. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Krogh-Madsen, P. Schaffer, A. D. Skriver, L. K. Taylor, B. Pelzmann, B. Koidl, and M. R. Guevara An ionic model for rhythmic activity in small clusters of embryonic chick ventricular cells Am J Physiol Heart Circ Physiol, July 1, 2005; 289(1): H398 - H413. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. K. Lancaster, S. A. Jones, S. M. Harrison, and M. R. Boyett Intracellular Ca2+ and pacemaking within the rabbit sinoatrial node: heterogeneity of role and control J. Physiol., April 15, 2004; 556(2): 481 - 494. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. O. Verkerk, R. Wilders, R. Coronel, J. H. Ravesloot, and E. E. Verheijck Ionic Remodeling of Sinoatrial Node Cells by Heart Failure Circulation, August 12, 2003; 108(6): 760 - 766. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J M Ridley, J T Milnes, Y H Zhang, H J Witchel, and J C Hancox Inhibition of HERG K+ current and prolongation of the guinea-pig ventricular action potential by 4-aminopyridine J. Physiol., June 15, 2003; 549(3): 667 - 672. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Honjo, S. Inada, M.K. Lancaster, M. Yamamoto, R. Niwa, S.A. Jones, N. Shibata, K. Mitsui, T. Horiuchi, K. Kamiya, et al. Sarcoplasmic Reticulum Ca2+ Release Is Not a Dominating Factor in Sinoatrial Node Pacemaker Activity Circ. Res., February 21, 2003; 92 (3): e41 - e44. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Kurata, I. Hisatome, S. Imanishi, and T. Shibamoto Dynamical description of sinoatrial node pacemaking: improved mathematical model for primary pacemaker cell Am J Physiol Heart Circ Physiol, November 1, 2002; 283(5): H2074 - H2101. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Musa, M. Lei, H. Honjo, S. A. Jones, H. Dobrzynski, M. K. Lancaster, Y. Takagishi, Z. Henderson, I. Kodama, and M. R. Boyett Heterogeneous Expression of Ca2+ Handling Proteins in Rabbit Sinoatrial Node J. Histochem. Cytochem., March 1, 2002; 50(3): 311 - 324. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Lei, P. J Cooper, P. Camelliti, and P. Kohl Role of the 293b-sensitive, slowly activating delayed rectifier potassium current, iKs, in pacemaker activity of rabbit isolated sino-atrial node cells Cardiovasc Res, January 1, 2002; 53(1): 68 - 79. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Honjo, M. R Boyett, S. R Coppen, Y. Takagishi, T. Opthof, N. J Severs, and I. Kodama Heterogeneous expression of connexins in rabbit sinoatrial node cells: correlation between connexin isotype and cell size Cardiovasc Res, January 1, 2002; 53(1): 89 - 96. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. O Verkerk and A. C.G van Ginneken Considerations in studying the transient outward K+ current in cells exhibiting the hyperpolarization-activated current Cardiovasc Res, December 1, 2001; 52(3): 517 - 518. [Full Text] [PDF]
|
|
|
|
|
|
M.R Boyett, H Honjo, M Lei, and I Kodama Transient outward K+ current, ito, in the sinoatrial node Cardiovasc Res, December 1, 2001; 52(3): 519 - 520. [Full Text] [PDF]
|
|
|
|
|
|
M Lei, H Honjo, I Kodama, and M R Boyett Heterogeneous expression of the delayed-rectifier K+ currents iK,r and iK,s in rabbit sinoatrial node cells J. Physiol., September 15, 2001; 535(3): 703 - 714. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Huelsing, A. E. Pollard, and K. W. Spitzer Transient outward current modulates discontinuous conduction in rabbit ventricular cell pairs Cardiovasc Res, March 1, 2001; 49(4): 779 - 789. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M.R. Boyett, H. Honjo, and I. Kodama The sinoatrial node, a heterogeneous pacemaker structure Cardiovasc Res, September 1, 2000; 47(4): 658 - 687. [Abstract] [Full Text] [PDF]
|
|