(Circulation. 1995;92:3061-3069.)
© 1995 American Heart Association, Inc.
Articles |
Regional Differences in Transient Outward Current Density and Inhomogeneities of Repolarization in Rabbit Right Atrium
From the Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan; and Tsukuba Research Laboratories (K.S.), Eisai Co, Ltd, Ibaragi-ken, Japan.
Correspondence to Takeshi Yamashita, MD, The Second Department of Internal Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan.
Background Recent experimental and clinical studies on atrial flutter have demonstrated that the crista terminalis (CT) plays an important role in the genesis of atrial reentry. To elucidate the underlying mechanism of its role, we characterized the electrophysiological repolarization properties of CT cells by comparing them with those of the pectinate muscles (PM).
Methods and Results After action potential properties of both regions were compared by conventional microelectrode technique in multicellular atrial tissues, the whole-cell clamp experiments were applied in atrial cells isolated from both regions. Action potential duration (APD) was more prolonged in CT than in PM in multicellular preparations (APD90 77±5 ms versus 52±8 ms at 1 Hz, P<.01), though the other properties did not differ significantly. Similarly, in isolated atrial cells, APD was more prolonged in CT cells than in PM cells (APD90 63±7 ms versus 41±6 ms at 0.1 Hz, P<.01). Isolated single cells were larger in CT than in PM. The whole-cell clamp recordings showed no definite distinctions in the density of the voltage-dependent L-type Ca2+ current and the inwardly rectifying K+ current between these cells but revealed a significant reduction of the density of the 4-aminopyridine–sensitive transient outward current (Ito) in CT cells compared with that in PM cells (6.3±0.7 pA/pF versus 10.3±0.8 pA/pF at +20 mV, P<.05). However, no differences in the kinetics or the voltage dependence of Ito were observed between the cells. The time course of recovery from inactivation of Ito was also similar in both types of cells.
Conclusions These results suggest that the preferential reduction in the density of Ito in the CT cells could contribute to prolong their APD, which may be related to the genesis of atrial reentry.
Key Words: action potentials • arrhythmias
This article has been cited by other articles:
 |
|
 |
|
  A. Michailova, W. Lorentz, and A. McCulloch Modeling transmural heterogeneity of KATP current in rabbit ventricular myocytes Am J Physiol Cell Physiol, August 1, 2007; 293(2): C542 - C557. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Nygren, A. E. Lomax, and W. R. Giles Heterogeneity of action potential durations in isolated mouse left and right atria recorded using voltage-sensitive dye mapping Am J Physiol Heart Circ Physiol, December 1, 2004; 287(6): H2634 - H2643. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Burashnikov, S. Mannava, and C. Antzelevitch Transmembrane action potential heterogeneity in the canine isolated arterially perfused right atrium: effect of IKr and IKur/Ito block Am J Physiol Heart Circ Physiol, June 1, 2004; 286(6): H2393 - H2400. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. E. Lomax, C. S. Kondo, and W. R. Giles Comparison of time- and voltage-dependent K+ currents in myocytes from left and right atria of adult mice Am J Physiol Heart Circ Physiol, November 1, 2003; 285(5): H1837 - H1848. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Yamashita, A. Sekiguchi, Y.-k. Iwasaki, K. Sagara, H. Iinuma, S. Hatano, L.-T. Fu, and H. Watanabe Circadian Variation of Cardiac K+ Channel Gene Expression Circulation, April 15, 2003; 107(14): 1917 - 1922. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. Berenfeld, A. V. Zaitsev, S. F. Mironov, A. M. Pertsov, and J. Jalife Frequency-Dependent Breakdown of Wave Propagation Into Fibrillatory Conduction Across the Pectinate Muscle Network in the Isolated Sheep Right Atrium Circ. Res., June 14, 2002; 90(11): 1173 - 1180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Schram, M. Pourrier, P. Melnyk, and S. Nattel Differential Distribution of Cardiac Ion Channel Expression as a Basis for Regional Specialization in Electrical Function Circ. Res., May 17, 2002; 90(9): 939 - 950. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. A. Boyden Three Things You Should Know When Considering the Atria : Location, Location, Location Circ. Res., June 8, 2001; 88(11): 1097 - 1098. [Full Text] [PDF]
|
|
|
|
 |
|
 M. Lei, H. Honjo, I. Kodama, and M.R. Boyett Characterisation of the transient outward K+ current in rabbit sinoatrial node cells Cardiovasc Res, June 1, 2000; 46(3): 433 - 441. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Honjo, M. Lei, M. R. Boyett, and I. Kodama Heterogeneity of 4-aminopyridine-sensitive current in rabbit sinoatrial node cells Am J Physiol Heart Circ Physiol, April 1, 1999; 276(4): H1295 - H1304. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. R. Boyett, H. Honjo, M. Yamamoto, M. R. Nikmaram, R. Niwa, and I. Kodama Downward gradient in action potential duration along conduction path in and around the sinoatrial node Am J Physiol Heart Circ Physiol, February 1, 1999; 276(2): H686 - H698. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. R. Boyett, H. Honjo, M. Yamamoto, M. R. Nikmaram, R. Niwa, and I. Kodama Regional differences in effects of 4-aminopyridine within the sinoatrial node Am J Physiol Heart Circ Physiol, October 1, 1998; 275(4): H1158 - H1168. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Feng, L. Yue, Z. Wang, and S. Nattel Ionic Mechanisms of Regional Action Potential Heterogeneity in the Canine Right Atrium Circ. Res., September 7, 1998; 83(5): 541 - 551. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Yamashita, Y. Murakawa, K. Ajiki, and M. Omata Incidence of Induced Atrial Fibrillation/Flutter in Complete Atrioventricular Block: A Concept of `Atrial-Malfunctioning' Atrio-Hisian Block Circulation, February 4, 1997; 95(3): 650 - 654. [Abstract] [Full Text]
|
|