Mechanism of Shortening of Atrial Refractory Period After Short Term Rapid Pacing

摘要

Purpose: To investigate the mechanisms of the shortening of atrial effective refractory period (ERP) after a rapid pacing of 50Hz for lOmin.Method: The excised hearts from Japanese white rabbits (2-2.5kg) were used with a LangendorfT perfusing apparatus (n=148).Results: Verapamil, ryanodine, and W-7 inhibited the ERP shortening (%ERP=98%). Pilsicainide and chromanol 293b did not inhibit the ERP shortening (%ERP=45%, 9%, respectively), but promoted the recovery.Conclusion: Even a short term rapid pacing could induce the ERP shortening. This phenomenon was not associated with the changes of membrane channels, but with intra-cellular calcium handling.