HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/H2144    most recent 00924.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Katra, R. P. Articles by Laurita, K. R. Search for Related Content PubMed PubMed Citation Articles by Katra, R. P. Articles by Laurita, K. R.

Ryanodine receptor dysfunction and triggered activity in the heart

The Heart and Vascular Research Center, MetroHealth Campus, and the Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio

Submitted 25 August 2006 ; accepted in final form 18 December 2006

Arrhythmogenesis has been increasingly linked to cardiac ryanodine receptor (RyR) dysfunction. However, the mechanistic relationship between abnormal RyR function and arrhythmogenesis in the heart is not clear. We hypothesize that, under abnormal RyR conditions, triggered activity will be caused by spontaneous calcium release (SCR) events that depend on transmural heterogeneities of calcium handling. We performed high-resolution optical mapping of intracellular calcium and transmembrane potential in the canine left ventricular wedge preparation (n = 28). Rapid pacing was used to initiate triggered activity under normal and abnormal RyR conditions induced by FKBP12.6 dissociation and -adrenergic stimulation (20–150 µM rapamycin, 0.2 µM isoproterenol). Under abnormal RyR conditions, almost all preparations experienced SCRs and triggered activity, in contrast to control, rapamycin, or isoproterenol conditions alone. Furthermore, under abnormal RyR conditions, complex arrhythmias (monomorphic and polymorphic tachycardia) were commonly observed. After washout of rapamycin and isoproterenol, no triggered activity was observed. Surprisingly, triggered activity and SCRs occurred preferentially near the epicardium but not the endocardium (P < 0.01). Interestingly, the occurrence of triggered activity and SCR events could not be explained by cytoplasmic calcium levels, but rather by fast calcium reuptake kinetics. These data suggest that, under abnormal RyR conditions, triggered activity is caused by multiple SCR events that depend on the faster calcium reuptake kinetics near the epicardium. Furthermore, multiple regions of SCR may be a mechanism for multifocal arrhythmias associated with RyR dysfunction.

spontaneous calcium release; sudden death; arrhythmia mechanisms

This article has been cited by other articles:

				C. H. George Sarcoplasmic reticulum Ca2+ leak in heart failure: mere observation or functional relevance? Cardiovasc Res, January 15, 2008; 77(2): 302 - 314. [Abstract] [Full Text] [PDF]

				S. Gyorke and D. Terentyev Modulation of ryanodine receptor by luminal calcium and accessory proteins in health and cardiac disease Cardiovasc Res, January 15, 2008; 77(2): 245 - 255. [Abstract] [Full Text] [PDF]