Objective To investigate the effects of adenosine (Ado) on myocardiac electrophysiology in simulated ischemia and reperfusion in guinea-pig ventricular myocytes. Methods Electrical activity was recorded using standard intracellular microelectrode technique. Right ventricle was superfused with simulated ischemic Tyrode's solution for 15 min, and reperfued with normal Tyrode's solution for 30 min. Results The results showed Ado had no measurable effects on guinea-pig ventricular myocytes in normal Tyrode's solution. In the presence of Ado, maximal diastolic potential tended to be more depolarized during ischemia, and action potential (AP) parameters were abbreviated greatly in a concentration-dependent manner. Especially, the concentration of Ado 100 μmol·L-1 had significant effects on AP parameters in ischemic phase [APD30, APD50, and APD90 reduced by (86 ± 8) ％ versus (65± 6) ％, (70± 7)％versus (50±6)％, and (60±6)％versus (42±4)％ for control after 15 min, P＜0.05]. During reperfusion, AP parameters did not completely return to initial values in presence of Ado. This study illustrated that Ado significantly decreased incidence of arrhythmias induced by ischemia and reperfusion (in presence of Ado 100 μmol·L-1, the incidence of DAD decreased by 17％ versus 82％ for control during reperfusion). Conclusion Ado has no significant effects on guinea-pig ventricle in normal conditions, abbreviates greatly AP parameters during ischemia with a concentration-dependent manner, and has marked antiarrhythmic effects in ischemia and reperfusion.
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