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(Circulation Research. 2008;102:e52.)
© 2008 American Heart Association, Inc.

Letter to the Editor

Calcium Dynamics and Ventricular Fibrillation

Masahiro Ogawa, Shien-Fong Lin

The Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis

James N. Weiss

Division of Cardiology, Department of Medicine and Physiological Sciences, University of California, Los Angeles

Peng-Sheng Chen

The Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, chenpp@iupui.edu

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

To the Editor:

Warren et al¹ recently performed an optical mapping study in blood-perfused pig hearts. They concluded that their results did not support the presence of nonvoltage-gated intracellular calcium (Ca_i) transients during ventricular fibrillation (VF) and suggested that action potential (AP)/Ca_i transient dissociation is a consequence rather than a cause of wave fragmentation. A major piece of evidence in support of this conclusion is the failure of BAPTA-AM, a calcium chelator, in preventing VF in these pig hearts. These latter experiments were performed by perfusing the heart with 25 mg of BAPTA-AM in 1.5 L of Tyrode solution over a 10-minute period. The hearts were then blood-perfused, and the studies on VF induction were performed.

BAPTA-AM is known to incorporate into tissues slowly, and 20 to 60 minutes of infusion are generally needed before testing the antiarrhythmic effects.^2,3,4 To test whether or not the duration of BAPTA-AM infusion affected its antifibrillatory effects, we performed a study with hearts harvested from 4 New Zealand White rabbits (3.5 to 4.6 kg). The hearts were Langendorff-perfused with oxygenated Tyrode solution equilibrated with 95% O₂ and 5%CO₂ to maintain a pH of 7.4±0.05 at a rate of 35 to 45 mL/min. The coronary perfusion pressure was regulated and maintained at 70 to 80 cm of H₂O. We infused BAPTA-AM 20 µmol/L for 30 minutes (N=2) and for 70 minutes (N=2) before the commencement of the rapid-pacing protocol. The results showed that BAPTA-AM infusion for 30 minutes failed to suppress either Ca_i . . . [Full Text of this Article]

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