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Atrial L-type Ca2+ currents and human atrial fibrillation
D R Van Wagoner1, A L Pond, M Lamorgese
1Department of Cardiology and Kaufman Center for Heart Failure, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. vanwagd@ccf.org
Circulation Research
|September 4, 1999
Summary
Chronic atrial fibrillation (AF) involves reduced L-type calcium current (I(Ca)) in heart cells. Paradoxically, higher I(Ca) may increase the risk of developing AF after surgery.
Area of Science:
- Cardiology
- Electrophysiology
- Cellular Biology
Background:
- Chronic atrial fibrillation (AF) is linked to impaired atrial function.
- Animal models suggest reduced L-type calcium current (I(Ca)) contributes to AF pathophysiology.
- Human studies on I(Ca) in chronic AF are limited.
Purpose of the Study:
- To investigate the impact of chronic AF on I(Ca) density in human atrial myocytes.
- To explore the relationship between I(Ca) and the incidence of postoperative AF.
Main Methods:
- Compared I(Ca) in atrial myocytes from chronic AF patients and control patients in normal sinus rhythm.
- Utilized electrophysiological techniques to measure I(Ca).
- Assessed I(Ca) response to beta-adrenergic stimulation and its correlation with postoperative AF incidence.
Main Results:
- Significantly reduced I(Ca) density was observed in myocytes from chronic AF patients compared to controls.
- No differences were found in voltage dependence of activation or inactivation.
- Higher I(Ca) levels correlated with increased incidence of postoperative AF, irrespective of age or diagnosis.
Conclusions:
- Reduced atrial I(Ca) in chronic AF may be an adaptive response to calcium overload.
- Elevated I(Ca) might predispose individuals to AF initiation, potentially through calcium overload mechanisms.
- I(Ca) plays a complex role in both the maintenance and initiation of atrial fibrillation.