The action of theophylline on potassium uptake in cardiac purkinje fibers

E Musso, M Vassalle


The effect of theophylline on potassium uptake of cardiac Purkinje fibers was studied under different conditions. The following results were obtained: (1) theophylline decreases K uptake and enhances Purkinje fiber automaticity; (2) norepinephrine and high [Ca]0 counteract the decrease in K uptake induced by theophylline; (3) adrenergic receptor blockers do not modify the effect of theophylline on K uptake; (4) norepinephrine increases K uptake and this effect is potentiated by theophylline and is little affected by imidazole and acetylcholine. It is concluded that theophylline may depress K uptake by releasing intracellular calcium and thereby inhibiting the sodium-potassium pump. However, theophylline potentiates the effect of norepinephrine on K uptake probably by enhancing the intracellular levels of cyclic AMP.


Apr 1, 1983·Circulation Research·P LechatT W Smith

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