ABSTRACT
The purpose of the present study was to investigate the effects of different concentrations of ethanol on action potential (AP) in the isolated rat myocardium and the possible mechanism of electric-physiological changes. Standard microelectrode technique was used to record AP in isolated rat myocardium, and whole cell patch clamp technique was used to record the human Kv1.5 (hKv1.5) channel currents in HEK293 cells. The effects of different concentrations of ethanol (6.25, 12.5, 25.0, 50.0, 100.0 and 200.0 mmol/L) on AP parameters in rat atrium and papillary and Kv1.5 channel currents in HEK293 cells were analyzed. The results showed that in isolated atrium, action potential amplitude (APA), action potential duration (APD), action potential duration of 50% repolarization (APD(50)) and action potential duration of 90% repolarization (APD(90)) were not affected by 6.25 and 12.5 mmol/L ethanol, while APD, APD(50) and APD(90) were prolonged significantly by 25.0-200.0 mmol/L ethanol (P < 0.05 or P < 0.01), and APA was reduced with 100.0 and 200.0 mmol/L ethanol (P < 0.05 or P < 0.01). In isolated papillary, APA, APD, APD(50) and APD(90) were not affected by 6.25-25.0 mmol/L ethanol, while APD, APD(50) and APD(90) were prolonged significantly with 50.0-200.0 mmol/L ethanol (P < 0.05 or P < 0.01), and APA was reduced with 200.0 mmol/L ethanol (P < 0.05). The Kv1.5 channel currents were inhibited by ethanol in a concentration dependent manner in HEK293 cells. These findings suggest that 6.25 and 12.5 mmol/L ethanol produce no effects on AP parameters, and 50.0-200.0 mmol/L ethanol prolong APD significantly in isolated rat atrium and papillary. The prolonged effect on APD in isolated myocardium may be due to the inhibition of the Kv1.5 channel currents.
