Dietary fish oil reduces the incidence of triggered arrhythmias in pig ventricular myocytes.
BACKGROUND
Fish oil reduces the incidence of sudden cardiac death in postmyocardial infarction patients. Triggered activity is the principal mechanism of arrhythmogenesis under these conditions.


OBJECTIVE
The purpose of this study was to test whether dietary fish oil in pigs inhibits Ca2+ overload-induced triggered activity.


METHODS
Pigs were fed a diet of fish oil or sunflower oil for 8 weeks. Ventricular myocytes (omega3: fish oil, n = 11; control: sunflower oil, n = 8) were isolated by enzymatic dissociation and used for patch clamp studies and intracellular Ca2+ recordings. Triggered activity was induced by rapid pacing in the presence of norepinephrine.


RESULTS
Dietary fish oil reduced the incidence of triggered action potentials and delayed afterdepolarizations compared to control (9.1% in omega3 and 84.6% in control, P <.05), concomitant with a reduction in spontaneous Ca2+ release. Dietary fish oil prevented Ca2+ overload and reduced action potential prolongation in response to norepinephrine (DeltaAPD(90): 23.2 +/- 8.5 ms in omega3 and 107.4 +/- 15.9 in control, P <.05). omega3 myocytes displayed decreased sarcoplasmic reticulum Ca2+ content, reduced L-type Ca2+ current (I(Ca,L)), and less recruitment of the Na+/Ca2+ exchange current (I(NCX)) in response to norepinephrine compared to control. In the absence of norepinephrine, the slow component of the delayed rectifier current (I(Ks)) was larger in omega3 myocytes. In the presence of norepinephrine, I(Ks) increased to the same level in omega3 and control myocytes.


CONCLUSIONS
Dietary fish oil reduces the incidence of triggered activity and prevents Ca2+ overload and AP prolongation in response to norepinephrine. Fish oil may prevent arrhythmias in patients with heart failure.
Berecki
Géza
G
Experimental Cardiology Group (ECG), Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
Den Ruijter
Hester M
HM
Verkerk
Arie O
AO
Schumacher
Cees A
CA
Baartscheer
Antonius
A
Bakker
Diane
D
Boukens
Bastiaan J
BJ
van Ginneken
Antoni C G
AC
Fiolet
Jan W T
JW
Opthof
Tobias
T
Coronel
Ruben
R
D000200:Action Potentials; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000517:prevention & control*; D015220:Calcium Channels / Q000187:drug effects; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D004391:Dust; D005395:Fish Oils / Q000494:pharmacology*; D006352:Heart Ventricles / Q000187:drug effects*; D015994:Incidence; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D032342:Muscle Cells / Q000187:drug effects*; D009752:Nutritional Status; D010743:Phospholipids; D012307:Risk Factors; D013552:Swine; D013997:Time Factors
D015220:Calcium Channels; D004391:Dust; D005395:Fish Oils; D010743:Phospholipids