Effects of Acetaldehyde on Action Potentials and Ca2+ Currents in Single Atrial Myocytes from the Bullfrog

Aim: The purpose of the present study was to examine the effects of acetaldehyde on the contractile force and membrane potentials and currents in the bullfrog heart. Methods: Contractile force was recorded using right atrial tissues, and membrane potentials and currents were measured by using whole cell patch clamp methods in right atrial myocytes. Results: Acetaldehyde at 500 µmol/l and 1 mmol/l increased the contractile force significantly. Acetaldehyde at 300 and 500 µmol/l increased the overshoot and the plateau of electrically induced action potentials in a concentration-dependent and reversible manner, while the resting membrane potential did not change. The duration of the action potential (APD90) measured at the 90% repolarization level was shortened. The L-type Ca2+ current (ICa) increased significantly when 300 and 500 µmol/l were applied. The fast transient inward current, the inward rectifying potassium current and the outward delayed-rectifier potassium current were not changed following acetaldehyde application (500 µmol/l or 1 mmol/l). Conclusion: These results suggest that acetaldehyde increased the ICa, thereby increased the contractile force, the overshoot and the plateau of action potentials. The shortening of APD90 may be due to the acceleration of the current decay during the ICa inactivation phase.