EFFECT OF ANTIARRHYTHMIC DRUGS ON CHOLINE UPTAKE IN CARDIAC-CELLS IN CULTURE

Objective: The aim was to examine the effect on choline uptake of various antiarrhythmic drugs: lignocaine, tocainide, encainide, flecaninde, propafenone, procainamide, N-acetylprocainamide, bretylium, and amiodarone. Methods: Cardiac ventricular myocytes from 7 d old chick embryos were exposed in culture to these drugs, at concentrations ranging from 10(-6) to 10(-4) M, for 24 h. Myocyte choline uptake was assessed by the addition of methyl [3H] choline to media. After 120 min, media were removed, the cells were harvested, and intracellular [3H] actively was counted. Results: Lignocaine and tocainide produced a significant (p < 0.05) dose dependent increase in intracellular [methyl 3H] choline. Encainide produced a small increase and flecainide a small decrease in choline, neither of which was dose dependent. Propafenone significantly (p < 0.05) altered choline uptake: at 10(-6) M and 10(-5) M choline uptake was increased and at 10(-4) M it was decreased. Amiodarone produced a marked and significant (p < 0.05) dose dependent reduction in choline uptake. Bretylium, procainamide, and N-acetylprocainamide did not alter myocyte choline. Conclusions: Choline incorporation into cardiac myocyte is altered by some antiarrhythmic drugs, suggesting this may be part of their antiarrhythmic properties.