AJP - Heart Calcium Transients and Cell-Sarcomere
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Heart Circ Physiol 279: H130-H138, 2000;
0363-6135/00 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (18)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Li, G.-R.
Right arrow Articles by Baumgarten, C. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Li, G.-R.
Right arrow Articles by Baumgarten, C. M.
Vol. 279, Issue 1, H130-H138, July 2000

Existence of a transient outward K+ current in guinea pig cardiac myocytes

Gui-Rong Li1,2, Baofeng Yang1, Haiying Sun1, and Clive M. Baumgarten2

1 Department of Medicine, Montreal Heart Institute and University of Montreal, Montreal, Quebec, Canada H3C 3J7; and 2 Department of Physiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia 23298

A novel transient outward K+ current that exhibits inward-going rectification (Ito.ir) was identified in guinea pig atrial and ventricular myocytes. Ito.ir was insensitive to 4-aminopyridine (4-AP) but was blocked by 200 µmol/l Ba2+ or removal of external K+. The zero current potential shifted 51-53 mV/decade change in external K+. Ito.ir density was twofold greater in ventricular than in atrial myocytes, and biexponential inactivation occurs in both types of myocytes. At -20 mV, the fast inactivation time constants were 7.7 ± 1.8 and 6.1 ± 1.2 ms and the slow inactivation time constants were 85.1 ± 14.8 and 77.3 ± 10.4 ms in ventricular and atrial cells, respectively. The midpoints for steady-state inactivation were -36.4 ± 0.3 and -51.6 ± 0.4 mV, and recovery from inactivation was rapid near the resting potential (time constants = 7.9 ± 1.9 and 8.8 ± 2.1 ms, respectively). Ito.ir was detected in Na+-containing and Na+-free solutions and was not blocked by 20 nmol/l saxitoxin. Action potential clamp revealed that Ito.ir contributed an outward current that activated rapidly on depolarization and inactivated by early phase 2 in both tissues. Although it is well known that 4-AP-sensitive transient outward current is absent in guinea pig, this Ba2+-sensitive and 4-AP-insensitive K+ current has been overlooked.

transient outward potassium current; whole cell patch clamp; repolarization; excitability; action potential configuration


This article has been cited by other articles:


Home page
 CirculationHome page
G.-R. Li, H.-B. Wang, G.-W. Qin, M.-W. Jin, Q. Tang, H.-Y. Sun, X.-L. Du, X.-L. Deng, X.-H. Zhang, J.-B. Chen, et al.
Acacetin, a Natural Flavone, Selectively Inhibits Human Atrial Repolarization Potassium Currents and Prevents Atrial Fibrillation in Dogs
Circulation, May 13, 2008; 117(19): 2449 - 2457.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
R. Tao, C.-P. Lau, H.-F. Tse, and G.-R. Li
Functional ion channels in mouse bone marrow mesenchymal stem cells
Am J Physiol Cell Physiol, November 1, 2007; 293(5): C1561 - C1567.
[Abstract] [Full Text] [PDF]

Home page
 J. Physiol.Home page
S. Gasparini, A. Losonczy, X. Chen, D. Johnston, and J. C. Magee
Associative pairing enhances action potential back-propagation in radial oblique branches of CA1 pyramidal neurons
J. Physiol., May 1, 2007; 580(3): 787 - 800.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Gastrointest. Liver Physiol.Home page
B. Chen, G. Nicol, and W. K. Cho
Electrophysiological characterization of volume-activated chloride currents in mouse cholangiocyte cell line
Am J Physiol Gastrointest Liver Physiol, December 1, 2004; 287(6): G1158 - G1167.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
P. Zhabyeyev, T. Asai, S. Missan, and T. F. McDonald
Transient outward current carried by inwardly rectifying K+ channels in guinea pig ventricular myocytes dialyzed with low-K+ solution
Am J Physiol Cell Physiol, November 1, 2004; 287(5): C1396 - C1403.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Cell Physiol.Home page
F. Brette, J.-Y. Le Guennec, and I. Findlay
Low-voltage triggering of Ca2+ release from the sarcoplasmic reticulum in cardiac muscle cells
Am J Physiol Cell Physiol, December 1, 2003; 285(6): C1544 - C1552.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
S. Zicha, I. Moss, B. Allen, A. Varro, J. Papp, R. Dumaine, C. Antzelevich, and S. Nattel
Molecular basis of species-specific expression of repolarizing K+ currents in the heart
Am J Physiol Heart Circ Physiol, October 1, 2003; 285(4): H1641 - H1649.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
I. Findlay
Is there an A-type K+ current in guinea pig ventricular myocytes?
Am J Physiol Heart Circ Physiol, February 1, 2003; 284(2): H598 - H604.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
G.-R. Li, C.-P. Lau, A. Ducharme, J.-C. Tardif, and S. Nattel
Transmural action potential and ionic current remodeling in ventricles of failing canine hearts
Am J Physiol Heart Circ Physiol, September 1, 2002; 283(3): H1031 - H1041.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online