RESUMO
OBJECTIVE： To study the effects of ethyl acetate part form the ethanol extract of Periploca forrestii on cardiac function of isolated frog heart， and to primarily investigate its potential mechanism. METHODS： The isolated frog heart samples were prepared by using the intube method of steinmann. The Ren’s solution （blank control）， 1.70 mg/mL and 3.48 mg/mL ethyl acetate part from ethanol extract of P. forrestii were used to perfuse the sample. The BL-420 biological function experimental system was used to record the changes in heart rate and myocardial contractility. The effects of ethyl acetate part from ethanol extract of P. forrestii on cardiac function of isolated frog heart were investigated. After perfused with 10 mg/L atropine， 20 μL isoproterenol， 1 μL low calcium （per 1 000 mL pure water contain 0.06 g CaCl2）， high calcium Ren’s solution （per 1 000 mL pure water contain 0.24 g CaCl2）， adding 1.74 mg/mL ethyl acetate part from ethanol extract of P. forrestii， the changes of myocardial contractility in isolated hearts were recorded by BL-420 biological function experimental system. Myocardial tissue was collected after perfused with Ren’s solution （blank control） and ethyl acetate part from ethanol extract of P. forrestii with 1.74 and 3.48 mg/mL. The activity of Na+-K+-ATPase， Ca2+-Mg2+-ATPase and AChE were detected to investigate the potential mechanism of the effects of ethyl acetate extract from ethanol extract of P. forrestii on cardiac function. RESULTS： Compared with blank control， mean myocardial contractility was significantly decreased （P＜0.001） after adding 1.74， 3.48 mg/mL ethyl acetate part form ethanol extract of P. forrestii， but had no significant on heart rate （P＞0.05）. With the increase of extracellular Ca2+ concentration， the inhibitory effect of ethyl acetate part from ethanol extract of P. forrestii on isolated frog heart contraction also increased gradually. After adding atropine and isoproterenol， the inhibitory effect of the ethyl acetate part form ethanol extract of P. forrestii on isolated frog heart contraction decreased to some certain. The activity of Na+-K+-ATPase in cardiac tissue was not significantly changed （P＞0.05）， the activity of Ca2+-Mg2+-ATPase was significantly increased （P＜0.05）， and the activity of AChE was significantly decreased （P＜0.05） after perfused with 1.74， 3.48 mg/mL ethyl acetate part form ethanol extract of P. forrestii. CONCLUSIONS： The ethyl acetate part from the ethanol extract of P. forrestii can inhibit the contractile activity of the isolated frog heart and has a certain negative inotropic effect. The mechanism may be related to the increase of Ca2+-Mg2+-ATPase activity， inhibition of AChE activity， blocking of calcium channel in the cell membrane， the activation of M receptor and blocking of β receptor.
RESUMO
Objective To research and construct dynamic electrocardiograph (ECG) simulation model/algorithm to simulate different kinds of clinical ECG,where the heart rate can be infinitely variable,and to develop one platform for fast-demo and analysis of theoretical wave based on this algorithm which can be implemented in ECG training and teaching. Methods According to different characteristics decoupled one complete ECG wave to 4 parts,including P-wave,PR-section,QT -wave and TP -section. P -wave and QT -wave database were set up accordingly to find the relationship algorithm between PR-section and heart rate,TP-section and heart rate. With the synthesis work of the algorithm and clinical diagnosis theory,ECG simulation mathematical model /algorithm,dynamic link library.(dll) and software interface were developed by C++. Results Through comparing the ECG simulation results with clinical samples,the veracity and validity of the mathematical model/algorithm was verified. Conclusion The software module based on this model/algorithm is very valuable for ECG training and teaching in clinic,and can be implemented in the development of more advanced ECG relative software and devices.