Rhythmic phenomena are one of the most striking manifestations of dynamic behavior in biological systems. Understanding the mechanisms of biological rhythms, is crucial for understanding the dynamic of life. Each type...Rhythmic phenomena are one of the most striking manifestations of dynamic behavior in biological systems. Understanding the mechanisms of biological rhythms, is crucial for understanding the dynamic of life. Each type of dynamic behaviors may be related to the performance of both normal physiology and pathological. Conductive system of the heart can be stimulated to action as a network of elements and these elements show the oscillatory behavior then can be modeled as nonlinear oscillators. This paper provides the mathematical model of the heart rhythm by considering different states of Vanderpol nonlinear oscillators. Proposed oscillator model is designed in order to reproduce time series of action potential of natural pacemakers cardiac, such as SA or AV nodes. So model of heart is presented by a system of differential equations and to be considered chaotic or nonchaotic for different parameters of the model by using of the 0-1 test. Finally, the model is synchronized by applying an appropriate control signal, if it is needed.展开更多
Objective:To investigate the changes of left ventricular papillary muscle action potentials in guinea pigs with iron deficiency anemia and heart failure.Methods:A total of 20 cases of iron deficiency anemia with heart...Objective:To investigate the changes of left ventricular papillary muscle action potentials in guinea pigs with iron deficiency anemia and heart failure.Methods:A total of 20 cases of iron deficiency anemia with heart failure were treated with experimental group and 10 normal guinea pigs as control group. Blood samples were collected to determine hemoglobin content, red blood cell number and whole blood iron index, and the changes of cardiac function and hemodynamics were detected by 6240 biological signal collection system to determine whether the model was successful or not, Intracellular microelectrode technique was used to determine the action potentials of the papillary muscles in the model group and the control group. the potential amplitudes (APA), overshoot values (APA), maximum depolarization rate (Vmax), 20 % of repolarization, 50 % and 90 % of repolarization (APD20, APD50 and APD90 ) and the average velocity of repolarization were measured. Compare statistical difference between the model group and the control group.Results: 14 cases of model group survived completely, compared with control group, APD50 and APD90 prolonged, and the average velocity decreased.Conclusions: the action potential repolarization duration in the guinea pig papillary muscle of iron deficiency anemia with heart failure is prolonged, and the average repolarization velocity is slow.展开更多
As a special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cava (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the r...As a special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cava (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the right atrial (RA) cardiomyoctyes, the SVC cardiomyoctyes had longer APD90 at the different basic cycle lengths; the conduction block could be observed on both RA and SVC cardiomyoctyes. A few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously. Further more, we found that there are nonselective cation current (INs) in both SVC and RA cardiomyocytes. The peak density of INs in SVC cardiomyocytes was smaller than that in RA cardiomyocytes. Removal of extracellular divalent cation and glucose could increase INs in SVC cardiomyocytes. The agonist or the antagonist of INs may in-crease or decrease APD. To sum up, some SVC cardiomyocytes possess the ability of spontaneous activity; the difference of transmembrane action potentials between SVC and RA cardiomyocytes is partly because of the different density of INs between them; the agonist or the antagonist of INs can in-crease or decrease APD leading to the enhancement or reduction of EAD genesis in SVC cardiomyo-cytes. INs in rabbit myocytes is fairly similar to TRPC3 current in electrophysiological property, which might play an important role in the mechanisms of AF.展开更多
To exploring the effect of Allitridi on anti arrhythmia, cardiac electrophysiological characteristic are detected in guinea pig atrium muscles by intracellular microelectrode technique. Result:The automaticity which a...To exploring the effect of Allitridi on anti arrhythmia, cardiac electrophysiological characteristic are detected in guinea pig atrium muscles by intracellular microelectrode technique. Result:The automaticity which adrenalin induces is inhibited at 125 and 625 umol/L. The force of contraction is weakened; the intensity time curve which reflects excitability move towards right after 625 umol/L administration. under 25、125、625 μmol/L, functional refractory period、action potential duration of 50% and 90% repolarization、 sinus cycle longness are extended, a relationship between dose and effect exist at SCL. Conclusion: Automaticity、 excitability and refractoriness not only are inhibited but also action potential durations are extended after Allitridi administration.展开更多
文摘Rhythmic phenomena are one of the most striking manifestations of dynamic behavior in biological systems. Understanding the mechanisms of biological rhythms, is crucial for understanding the dynamic of life. Each type of dynamic behaviors may be related to the performance of both normal physiology and pathological. Conductive system of the heart can be stimulated to action as a network of elements and these elements show the oscillatory behavior then can be modeled as nonlinear oscillators. This paper provides the mathematical model of the heart rhythm by considering different states of Vanderpol nonlinear oscillators. Proposed oscillator model is designed in order to reproduce time series of action potential of natural pacemakers cardiac, such as SA or AV nodes. So model of heart is presented by a system of differential equations and to be considered chaotic or nonchaotic for different parameters of the model by using of the 0-1 test. Finally, the model is synchronized by applying an appropriate control signal, if it is needed.
文摘Objective:To investigate the changes of left ventricular papillary muscle action potentials in guinea pigs with iron deficiency anemia and heart failure.Methods:A total of 20 cases of iron deficiency anemia with heart failure were treated with experimental group and 10 normal guinea pigs as control group. Blood samples were collected to determine hemoglobin content, red blood cell number and whole blood iron index, and the changes of cardiac function and hemodynamics were detected by 6240 biological signal collection system to determine whether the model was successful or not, Intracellular microelectrode technique was used to determine the action potentials of the papillary muscles in the model group and the control group. the potential amplitudes (APA), overshoot values (APA), maximum depolarization rate (Vmax), 20 % of repolarization, 50 % and 90 % of repolarization (APD20, APD50 and APD90 ) and the average velocity of repolarization were measured. Compare statistical difference between the model group and the control group.Results: 14 cases of model group survived completely, compared with control group, APD50 and APD90 prolonged, and the average velocity decreased.Conclusions: the action potential repolarization duration in the guinea pig papillary muscle of iron deficiency anemia with heart failure is prolonged, and the average repolarization velocity is slow.
文摘As a special focus in initiating and maintaining atrial fibrillation (AF), cardiomyocytes in superior vena cava (SVC) have distinctive electrophysiological characters. In this study, we found that comparing with the right atrial (RA) cardiomyoctyes, the SVC cardiomyoctyes had longer APD90 at the different basic cycle lengths; the conduction block could be observed on both RA and SVC cardiomyoctyes. A few of SVC cardiomyoctyes showed slow response action potentials with automatic activity and some others showed early afterdepolarization (EAD) spontaneously. Further more, we found that there are nonselective cation current (INs) in both SVC and RA cardiomyocytes. The peak density of INs in SVC cardiomyocytes was smaller than that in RA cardiomyocytes. Removal of extracellular divalent cation and glucose could increase INs in SVC cardiomyocytes. The agonist or the antagonist of INs may in-crease or decrease APD. To sum up, some SVC cardiomyocytes possess the ability of spontaneous activity; the difference of transmembrane action potentials between SVC and RA cardiomyocytes is partly because of the different density of INs between them; the agonist or the antagonist of INs can in-crease or decrease APD leading to the enhancement or reduction of EAD genesis in SVC cardiomyo-cytes. INs in rabbit myocytes is fairly similar to TRPC3 current in electrophysiological property, which might play an important role in the mechanisms of AF.
文摘To exploring the effect of Allitridi on anti arrhythmia, cardiac electrophysiological characteristic are detected in guinea pig atrium muscles by intracellular microelectrode technique. Result:The automaticity which adrenalin induces is inhibited at 125 and 625 umol/L. The force of contraction is weakened; the intensity time curve which reflects excitability move towards right after 625 umol/L administration. under 25、125、625 μmol/L, functional refractory period、action potential duration of 50% and 90% repolarization、 sinus cycle longness are extended, a relationship between dose and effect exist at SCL. Conclusion: Automaticity、 excitability and refractoriness not only are inhibited but also action potential durations are extended after Allitridi administration.
文摘实验以正常犬和扩张型心肌病心力衰竭犬(dilated cardiomyopathy congestive heart failure,DCM-CHF)模型为对象、以心肌跨室壁复极离散的相关参数为指标,研究左心室心外膜起搏、双心室起搏(模拟临床上心室再同步治疗的方法)后的心肌电生理特性变化。实验以快速右心室起搏的方法制备DCM-CHF犬模型;正常犬和DCM-CHF犬均经射频消融希氏束制备三度房室传导阻滞模型;采用同步记录犬体表心电图和内膜下、中层、外膜下三层心肌单相动作电位(monophasic action potentials,MAP)的方法,测定不同部位起搏时的QT间期、Tpeak-Tend(Tp-Te)间期和三层心肌的单相动作电位时程(MAP duration,MAPD)、跨室壁复极离散度(transmural dispersion of repolaization,TDR)。结果显示:在正常犬,左室心外膜与双心室起搏后三层心肌的MAPD均延长,同时TDR增大(左室心外膜起搏47.16 ms、双心室起搏37.54 ms、右室心内膜起搏26.75 ms,P<0.001),体表心电图Tp-Te间期的变化与之平行;在DCM-CHF犬较正常犬已表现出中层心肌MAPD延长(276.30 ms vs 257.35 ms,P<0.0001)和TDR(33.8 ms vs 27.58 ms,P=0.002)增大的基础上,左室心外膜参与起搏后仍进一步使三层心肌的MAPD延长和TDR增大。研究结果提示,左室心外膜起搏和双心室起搏后使内膜下。
基金This work was supported by the National Natural Science Foundation of China (No. 30370571)the Natural Science Foundation of Hebei Province (No. 200400628)+2 种基金the Program for New Century Excellent Scholars Ministry of Eduction China (No. 04-0253)
