[Regulative effects of qixue injection on rhythmic activities in pacemaker cells of the sinoatrial node]

This study investigated, with microelectrode technic, the effects of electrical activities in pacemaker cells of sinoatrial node by Qixue injection consisting of Ginseng, Astragali and Angelicae sinensis, which may replenish the Qi and invigorate the circulation of blood. Qixue injection produced a negative chronotropic action on beating of sinoatrial node mainly because of lowering the rate of diastolic automatic depolarization and lengthening the duration of diastolic depolarization as well, but this action was caused through neither cholinergic M receptors nor adrenergic beta receptors. With hypoxia at temperature of 41 degrees C or with isoprenaline in existence to cause beating slowness and arrhythmia, Qixue injection turned them into rhythmical beating and quickened automatic beating frequency. It suggested that Qixue injection could antagonize pathologic changes caused by insufficiency of oxygen supply and improve function of sinoatrial node. Also it indicated that Qixue injection had a biphasic function on regulating rhythmical activities of sinoatrial node, which might be one of the mechanisms of the drug used clinically.