Docosahexaenoic acid has influence on action potentials and transient outward potassium currents of ventricular myocytes

Ru-Xing Wang,Tao Guo,Su-Xia Guo,Xiang-Jun Yang,Xiao-Rong Li,Zhen-Yu Yang,Li-Ping Sun,Wen-Ping Jiang

doi:10.1186/1476-511x-9-39

Abstract

BackgroundThere are many reports about the anti-arrhythmic effects of ω-3 polyunsaturated fatty acids, however, the mechanisms are still not completely delineated. The purpose of this study was to investigate the characteristics of action potentials and transient outward potassium currents (Ito) of Sprague-Dawley rat ventricular myocytes and the effects of docosahexaenoic acid (DHA) on action potentials and Ito.MethodsThe calcium-tolerant rat ventricular myocytes were isolated by enzyme digestion. Action potentials and Ito of epicardial, mid-cardial and endocardial ventricular myocytes were recorded by whole-cell patch clamp technique.Results1. Action potential durations (APDs) were prolonged from epicardial to endocardial ventricular myocytes (P < 0.05). 2. Ito current densities were decreased from epicardial to endocardial ventricular myocytes, which were 59.50 ± 15.99 pA/pF, 29.15 ± 5.53 pA/pF, and 12.29 ± 3.62 pA/pF, respectively at +70 mV test potential (P < 0.05). 3. APDs were gradually prolonged with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, however, APDs changes were not significant as DHA concentrations were in the range of 0 μmol/L to 1 μmol/L. 4. Ito currents were gradually reduced with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, and its half-inhibited concentration was 5.3 μmol/L. The results showed that there were regional differences in the distribution of action potentials and Ito in rat epicardial, mid-cardial and endocardial ventricular myocytes. APDs were prolonged and Ito current densities were gradually reduced with the increase of DHA concentrations.ConclusionThe anti-arrhythmia mechanisms of DHA are complex, however, the effects of DHA on action potentials and Ito may be one of the important causes.

Highlights

There are many reports about the anti-arrhythmic effects of ω-3 polyunsaturated fatty acids, the mechanisms are still not completely delineated
Action potential durations (APDs) were gradually prolonged with the increase of docosahexaenoic acid (DHA) concentrations from 1 μmol/L to 100 μmol/L, APDs changes were not significant as DHA concentrations were in the range of 0 μmol/L to 1 μmol/L. 4
Ito currents were gradually reduced with the increase of DHA concentrations from 1 μmol/L to 100 μmol/L, and its half-inhibited concentration was 5.3 μmol/L

Summary

Introduction

There are many reports about the anti-arrhythmic effects of ω-3 polyunsaturated fatty acids, the mechanisms are still not completely delineated. The beneficial effects of PUFAs on cardiovascular diseases, such as fish oil, have been reported, and the effects of PUFAs on anti-arrhythmias and prevention of sudden death have been highlights [3,4,5,6]. It has been reported that PUFAs have the roles of anti-arrhythmias and prevention of malignant ventricular arrhythmias, the mechanisms of which are still not completely delineated [7,8]. More attentions have been paid to their beneficial effects on cardiovascular diseases in recent years, especially in their antiarrhythmias and prevention of sudden cardiac death [913]. Most of these studies are clinical trials, and the mechanisms of which are still not completely known. To investigate the mechanisms of ω-3 PUFAs on anti-

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