Transient outward and delayed rectifier currents in canine atrium:
properties and role of isolation methods.
Yue, Lixia, Jianlin Feng, Gui-Rong Li, and Stanley Nattel.
Department of Medicine, Montreal Heart Institute, Montreal, Quebec
H1T 1C8; University of Montreal, Montreal, Quebec H3C 3J7;
Departement of Pharmacology and Therapeutics, McGill University,
Montreal, Quebec H3G 1Y6, Canada
APStracts 2:0524H, 1995.
While the dog is the principal species used for in vivo studies of
atrial arrhythmias, little is known about currents governing canine
atrial repolarization. Cells were isolated from dog atria by exposure
to collagenase of tissue in vitro ("chunk cells") and by
arterial perfusion ("perfusion cells"). Whole-cell voltage
clamp revealed transient outward K+ current (Ito1), Ca2+-dependent
Cl- current (Ito2), and delayed rectifier K+ current (IK). Ito1
recovered rapidly and showed little frequency-dependence. Two
components of IK were present: a rapidly-activating, E-4031 sensitive
current with marked inward rectification and a slower-activating E
-4031 insensitive component. Ito1 and IK resembled corresponding
currents previously described in human atrium. Transient outward
currents were similar in chunk and perfusion cells, but IK was seen
in 4% of chunk cells vs. 99% of perfusion cells (P < 0.001).
Suppression of each identified current retarded canine action
potential repolarization. We conclude that Ito1, Ito2, and both
components of IK are present in dog atrium, IK is much more sensitive
to isolation method than Ito1 or Ito2, and the properties of two
important repolarizing currents (Ito1 and IK) previously described in
human atrium are similar to those in dog atrium.
Received 8 June 1995; accepted in final form 3 November 1995.
APS Manuscript Number H525-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95