Copyright © 2006, European Society of Cardiology
Incorporated sarcolemmal fish oil fatty acids shorten pig ventricular action potentials
aExperimental and Molecular Cardiology Group, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
bDepartment of Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
cDepartment of Nutrition, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
dDepartment of Human Nutrition, the Wageningen Centre for Food Sciences, Wageningen University, Wageningen, The Netherlands
* Corresponding author. Academic Medical Center, Rm M0-108, Department of Experimental Cardiology, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Tel.: +31 20 5663267; fax: +31 20 6975458. Email address: R.Coronel{at}amc.uva.nl
Background Omega-3 polyunsaturated fatty acids (
3-PUFAs) from fish oil reduce the risk of sudden death presumably by preventing life-threatening arrhythmias. Acutely administered 3-PUFAs modulate the activity of several cardiac ion channels, but the chronic effects of a diet enriched with fish oil leading to 3-PUFA-incorporation into the sarcolemma on membrane currents are unknown.
Methods Pigs received a diet either rich in 3-PUFAs or in 9-fatty acids for 8weeks. Ventricular myocytes (VMs) were isolated and used for patch-clamp studies.
Results 3-VMs contained higher amounts of 3-PUFAs and had a shorter action potential (AP) with a more negative plateau than control VM. In 3 VMs, L-type Ca2+ current (ICa,L) and Na+–Ca2+ exchange current (INCX) were reduced by approximately 20% and 60%, respectively, and inward rectifier K+ current (IK1) and slow delayed rectifier K+ current (IKs) were increased by approximately 50% and 70%, respectively, compared to control. Densities of rapid delayed rectifier K+ current, Ca2+-activated Cl– current, and Na+ current (INa) were unchanged, although voltage-dependence of INa inactivation was more negative in 3 VMs.
Conclusions A fish oil diet increases 3-PUFA content in the ventricular sarcolemma, decreases ICa,L and INCX, and increases IK1 and IKs, resulting in AP shortening. Incorporation of 3-PUFAs in the sarcolemma may have consequences for arrhythmias independent of circulating 3-PUFAs.
KEYWORDS Ion channels; Ion exchangers; Membrane potential; Repolarization; Ca2+ transients; Nutrition; Fatty acids