Dietary flaxseed protects against ventricular fibrillation induced by ischemia-reperfusion in normal and hypercholesterolemic Rabbits.
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the (n-3) PUFA found in fish oils, exert antiarrhythmic effects during ischemia. Flaxseed is the richest plant source of another (n-3) PUFA, alpha-linolenic acid (ALA), yet its effects remain largely unknown. Our objective was to determine whether a flaxseed-rich diet is antiarrhythmic in normal and hypercholesterolemic rabbits. Male New Zealand White (NZW) rabbits (n = 14-16) were fed as follows: regular diet (REG group); diet containing 10% flaxseed (FLX group); 0.5% cholesterol (CHL group); or 0.5% cholesterol + 10% flaxseed (CHL/FLX group) for up to 16 wk. Plasma cholesterol was significantly elevated in the CHL and CHL/FLX groups. Plasma triglycerides were unchanged. ALA levels increased significantly in plasma and hearts of the FLX and CHL/FLX groups. After the feeding period, rabbit hearts were isolated and subjected to global ischemia (30 min) and reperfusion (45 min). Ventricular fibrillation (VF) occurred during ischemia in 33% of REG but in none of FLX hearts, and 28% of CHL but only 6% of CHL/FLX hearts. VF incidence during reperfusion was 28% and 26% in REG and FLX hearts, respectively. The incidence significantly increased to 64% in CHL hearts, and was significantly attenuated (18%) in CHL/FLX hearts. CHL markedly prolonged the QT interval, whereas FLX significantly shortened the QT interval and reduced arrhythmias in the FLX and CHL/FLX hearts. In vitro application of (n-3) PUFA shortened the action potential duration, an effect consistent with the QT data. This study demonstrates that dietary flaxseed exerts antiarrhythmic effects during ischemia-reperfusion in rabbit hearts, possibly through shortening of the action potential.
Ander
Bradley P
BP
National Centre for Agri-Food Research in Medicine, Department of Physiology, University of Manitoba, Winnipeg, Canada.
Weber
Anna R
AR
Rampersad
Penelope P
PP
Gilchrist
James S C
JS
Pierce
Grant N
GN
Lukas
Anton
A
D000818:Animals; D004195:Disease Models, Animal; D015525:Fatty Acids, Omega-3 / Q000627:therapeutic use; D006937:Hypercholesterolemia; D008043:Linseed Oil / Q000627:therapeutic use*; D008297:Male; D008517:Phytotherapy; D011817:Rabbits; D015427:Reperfusion Injury; D014693:Ventricular Fibrillation / Q000209:etiology / Q000517:prevention & control*; D017962:alpha-Linolenic Acid / Q000627:therapeutic use
D015525:Fatty Acids, Omega-3; D017962:alpha-Linolenic Acid; D008043:Linseed Oil