OBJECTIVE： To rapidly identify chemical components of Zhitong huazheng capsules （shorted for “ZTHZC”）， and to provide reference for further elucidating the pharmacodynamic material basis and overall quality control. METHODS： UPLC-Q-TOF/MS method was adopted to separate the chemical components of ZTHZC. By reviewing literatures that related to chemical components of ZTHZC and its single Chinese traditional medicinal crops， the chemical structure of the chemical components was saved into a .mol format file， and supplemented the UNIFI database. The chemical constituents of ZTHZC were qualitatively analyzed by UNIFI database screening， and validated according to their precise molecular mass， characteristic ions， neutral loss， secondary mass spectrometry cleavage， chromatographic retention behavior， combined reference information and literature reports. RESULTS： A total of 70 chemical components were identified in this experiment， including 38 organic acids and organic acid esters， 8 alkaloids， 9 flavonoids， 5 triterpenoid saponins， 5 aldehydes， 2 ketones， 1 quinone， 1 polyacetylene and 1 monoterpenoid. CONCLUSIONS： This study provides a rapid detection and identification method for chemical components of ZTHZC， and also provides a scientific basis for the clarification of ZTHZC’s quality control and pharmacodynamics.

Objective: To investigate the effects and mechanism of digoxin on atrium electrical remodeling and susceptibility of atrial fibrillation (AF) in aged rabbits. Methods: Twenty aged male New Zealand rabbits were divided into aged group and aged plus digoxin group (n=10 each). Electrical parameters including heart rate (HR), RR and QT interval, ST segment and P wave dispersion from normal Ⅱ electrocardiogram, and the maximum upstroke velocity (Max_dv/dt), plateau potential (plateau P), action potential duration of 10%, 20% and 90% (APD₁₀, APD₂₀, APD₉₀) from recording of monophasic action potential (MAP), as well as atrial effective refractory period (AERP₂₀₀) and dispersion (dERP₂₀₀) with 200 ms of basic cycle length (BCL), and frequency self adaptation of AERP with 300 ms and 150 ms of BCLs (fERP) were recorded and compared between the 2 groups. BCLs and inducibility of AF post programmed electrical stimulation and Burst-pacing in left atrium tissue of rabbits in vivo were also analyzed. The L-type calcium current (I_Ca-L) in 2 groups were recorded via whole-cell patch clamp technique, and the fluorescence intensity of intracellular free Ca²⁺ was detected with Flup-3/AM loading by the laser scanning confocal microscope in enzymatically dissociated single rabbit atrial myocytes. Results: Compared with aged group, the heart rate was faster, RR and QT interval were obvious shorter, ST segment was raised and P wave dispersion was significantly increased in aged plus digoxin group (all P<0.05). Moreover, compared with aged group, the Max_dv/dt and plateau P were obviously increased, APD₁₀ and APD₂₀ were significantly prolongated, and APD₉0 was significantly shorter in aged plus digoxin group (all P<0.01). Otherwise, the fERP was markedly increased (0.81±0.15 vs. 0.67±0.05), and the induced rate of AF was obviously higher in aged plus digoxin group than in aged group (6/8 vs. 4/9) (all P<0.01). With voltage clamp model, digoxin significantly increased I_Ca-L of atrial myocytes of aged rabbits, When command potential was 10 mV, the current densities of I_Ca-L were significantly higher in digoxin group than that in aged group ((15.45±2.38) pA/pF vs. (7.03±1.69) pA/pF, P<0.01). Otherwise, the I-V curve of I_Ca-L was downward shifted of all I-V curves in digoxin perfused aged atrial cells of rabbits. Moreover, the fluorescence intensities of intracellular free Ca²⁺ was significantly higher in aged plus digoxin group than in aged group ((1 748±173) μmol/L vs. (478.13±87.63) μmol/L, P<0.01). Conclusion Digoxin could aggravate the atrial electrical remodeling in atrium of aged rabbits, facilitate susceptibility of atrial fibrillation in aged rabbit, increased current density of I_Ca-L and concentration of intracellular free Ca²⁺, followed Ca²⁺ overload and oscillations might be part of the underlying mechanisms.