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(Circulation Research. 2005;96:393.)
© 2005 American Heart Association, Inc.

Editorials

An Intimate Relationship

Ca²⁺ and Cardiac Ion Channels

Penelope A. Boyden, Henk E.D.J. ter Keurs

From the Department of Pharmacology, Center for Molecular Therapeutics (P.A.B., H.E.D.J.t.K.), Columbia University, New York, NY; and the Department of Medicine, Physiology, and Biophysics (H.E.D.J.t.K.), University of Calgary, Alberta, Canada.

Correspondence to Dr Penelope A. Boyden, Dept of Pharmacology, Columbia College of Physicians and Surgeons, 630 West 168th St., New York, NY 10032. E-mail pab4@columbia.edu

Key Words: action potentials • Ca_i transients • APD restitution

An extract of the first 250 words of the full text is provided, because this article has no abstract.

	Introduction

 
We last offered our ideas on the role of reverse EC coupling in the initiation of arrhythmias in 2001.¹ At that time we emphasized that spurious Ca²⁺ release or oscillations in Ca²⁺ levels could serve as possible triggers for arrhythmias. Since then much has been done to confirm this role for intracellular Ca²⁺.

At that time we did not discuss the role of Ca²⁺ cycling in the maintenance or conversion of stable tachycardias to VF. However, in consideration of the new data on the role of APD restitution in the initiation of VF (increase in wavebreaks; eg, see Garfinkel et al²), we turn our attention now to the role Ca²⁺ cycling in the myocyte and its impact on APD restitution relations in the isolated rabbit ventricular cell.³ Goldhaber et al consider the role of Ca²⁺ using different types of APD restitution protocols to emphasize the dynamic nature of intracellular Ca²⁺ changes and its subsequent impact on the myocyte APD.

In their study APD alternans is coupled to Ca²⁺ cycling, which in itself is not new since others have observed that APD alternans demonstrates a hystersis and is inhibited with BAPTA-AM buffering.⁴ Some have suggested that repolarization alternans is more closely associated with Ca²⁺ than APD restitution.^5–7 In fact there has been a large body of work implying that APD alternans and Ca²⁺ cycling are intimately linked (eg, see^8,9). However caution must be raised because Chudin et al¹⁰ have reported that the dynamics of Ca_i are altered even . . . [Full Text of this Article]

Related Article:

Action Potential Duration Restitution and Alternans in Rabbit Ventricular Myocytes: The Key Role of Intracellular Calcium Cycling

Joshua I. Goldhaber, Lai-Hua Xie, Tan Duong, Christi Motter, Kien Khuu, and James N. Weiss
Circ. Res. 2005 96: 459-466. [Abstract] [Full Text] [PDF]