Second Docosahexaenoic Acid On Rat Ventricular Myocytes Electrophysiological Effects And Antiarrhythmic Mechanism

Objective: To investigate the effects of docosahexenoic acids (DHA) on action potential (AP), sodium current (I_Na), L-type calcium current (I_Ca-L), transient outward potassium current (I_to), delayed rectifier potassium current (I_K) and inward rectifier potassium current (I_Ca-L,) of rat ventricular myocytes .Methods: We studied the acute effects of DHA on AP and I_Na, I_Ca-L, I_to, I_K and I_K1 recorded by whole-cell patch clamp techniques in adult rat ventricular myocytes isolated by enzyme digestion with three steps.Results: 1. The effects of DHA on I_to and I_K were concentration dependent but not I_K1; whereas low concentration of DHA (<20μmol/L) only inhibited I_to, higher concentration of DHA (>20μmol/L) inhibited I_to and I_K; 2. The effects of DHA on I_Na and I_Ca-Lwere concentration dependent; 3. DHA had concentration dependent effects on AP of rat ventricular myocytes. The action potential duration (APD) was not effected at low concentration of DHA (≤20μmol/L). However at a higher concentration(>20μmol/L), APD was gradually increased, and action potential amplitude (APA),overshoot (OS) and maximal depolarization rate (Vmax) were significant reduced in concentration dependent manner.Concluson: DHA has concentration dependent effects on AP, I_Na, I_Ca-L, I_to and I_K, but not I_K1, which may contribute to its antiarrythmatic activity.