Regulatory functions of docosahexaenoic acid on ion channels in rat ventricular myocytes.

Objective: The aim of this study was to study the regulatory functions of docosahexaenoic acid (DHA) on resting potential (RP), action potential duration (APD), delayed rectifier potassium current (Ik), and inwardly rectifier potassium current (Ik1) in rat ventricular myocytes, and analyze the related anti-arrhythmia mechanism.
Materials and Methods: Rat ventricular myocytes were isolated by enzyme digestion method. RP, APD, Ik and Ik1 in individual ventricular myocytes were recorded by patch-clamp technique with whole-cell configuration. Effects of DHA with various concentrations (0, 20, 40, 60, 80, 100 and 120 mmol/L, respectively) on RP, AP, Ik and Ik1 were investigated.
Results: There was no statistical difference of RP with different DHA concentrations (p > 0.05, n = 20), and the 25%, 50% and 90% of APD (APD25, APD50, and APD90) were gradually prolonged with increase of DHA concentration, respectively (p < 0.05, n = 20). IK gradually blocked and the I-V curve was downward shifted, according to increase of DHA concentration (p < 0.05, n = 20). The DHA half effect concentration (EC50) was 47.52 ± 2.32 µmol/L. With increasing DHA concentration, the steady-state inactivation curve shifted to left, and the recovery curve shifted to right. DHA had no significant effect on IK1 (p > 0.05, n = 20).
Conclusions: DHA has regulatory functions on RP, APD, Ik and Ik1 in rat ventricular myocytes, which may be one of the related antiarrhythmic mechanisms.