Effects of Phenanthrene on Electrical Activity of Ventricular Cardiomyocytes in Atlantic Cod (Gadus morhua)

Oil production in the Arctic shelf and its shipping via theNorthern Sea Route increase risks of pollution of Arctic ecosystemswith oil and its products. Polyaromatic hydrocarbons are known tobe the most toxic oil components, with phenanthrene being the mostabundant among them and causing the most robust effects. Phenanthreneis known for its high toxicity for developing fish hearts, withits cardiotoxic effects being species-specific. Meanwhile, the effectsof phenanthrene on cardiac function in Arctic fish, including commerciallyimportant fish species, are still poorly understood. Here, we studied theeffects of phenanthrene on electrical activity and ionic currentsin isolated ventricular cardiomyocytes of the Atlantic cod (Gadus morhua) using the patch clamptechnique. The major ionic currents in cod myocardium were I_Kr,I_K1, I_Na and I_Ca.Phenanthrene at a concentration of 1 µM (1) had no effect on theduration of action potentials (APs), (2) suppressed rapid delayedrectifier K⁺ current I_Kr by61.33 ± 3.94%, thus decreasing the repolarization reserve in cardiomyocytes,(3) had no effect on either the resting potential level or backgroundinward rectifier K⁺ current (I_K1),(4) decreased AP upstroke velocity due to suppression of fast Na⁺ current(I_Na), (5) insignificantly reduced the amplitudeof Ca²⁺ current (I_Ca)and accelerated its inactivation, which overall led to a decreasein I_Ca total cumulative charge transfer.Thus, the effects of phenanthrene on cod myocardium at a cellularlevel can be characterized as potentially proarrhythmic, which makescod populations in the Arctic seas vulnerable to pollution of theaquatic environment with toxic oil components during oil spillsin the event of man-made disasters.