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

Abstract

Background. There are many reports about the anti-arrhythmic effects of -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. Methods. The calcium-tolerant rat ventricular myocytes were isolated by enzyme digestion. Action potentials and Itoof epicardial, mid-cardial and endocardial ventricular myocytes were recorded by whole-cell patch clamp technique. Results. 1. Action potential durations (APDs) were prolonged from epicardial to endocardial ventricular myocytes (P < 0.05). 2. Itocurrent 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 mol/L to 100 mol/L, however, APDs changes were not significant as DHA concentrations were in the range of 0 mol/L to 1 mol/L. 4. Itocurrents were gradually reduced with the increase of DHA concentrations from 1 mol/L to 100 mol/L, and its half-inhibited concentration was 5.3 mol/L. The results showed that there were regional differences in the distribution of action potentials and Itoin rat epicardial, mid-cardial and endocardial ventricular myocytes. APDs were prolonged and I tocurrent densities were gradually reduced with the increase of DHA concentrations. Conclusion. The anti-arrhythmia mechanisms of DHA are complex, however, the effects of DHA on action potentials and Itomay be one of the important causes. © 2010 Wang et al.