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The aims of the present study were to examine the effect of heptanol on electrical coupling during ischemia, and to assess whether changes in electrical coupling by heptanol is associated with its cardiac protection. Perfused isolated rat hearts were subjected to a 24 min infusion of heptanol (0.05, 0.1, 0.5 or 1.0 mmol/L) followed by 70 min of global no-flow ischemia or by 20 min of regional ischemia...
Two series of experiments were performed in the perfused isolated rat heart to determine whether stimulation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical coupling during prolonged ischemia and whether these changes in electrical coupling is associated with the cardioprotection induced by U50,488H. It was found that U50,488H concentration...
We have developed a computational model for the rat cardiac ventricular cell by using electrophysiology data. Our control model (Pandit et al., 2001). The model represents the bioelectric activity in the left ventricular cells in adult male rats. We have described the differences in the membrane properties within the left ventricle to simulate the action potential variations of the endocardial and...
This article presents an analysis of the information rate of neural spike trains in an auditory nerve fiber (ANF) model stimulated extracellularly by sinusoidal electric stimuli under the case where a high-rate pulsatile waveform is presented as a conditioner for increasing the across-fiber-independency, i.e., desynchronization. In the computer simulation, stimulus current waveforms were presented...
Animal experiments, analog modeling and digital simulations are some means followed in laboratory practices to teach electrophysiological concepts. Advantages and disadvantages of these different strategies may change due to the teaching aims and education levels; none of these ways mentioned above is appropriate alone for all educational purposes. For a beginner who is coming up against the electrophysiological...
The gating of ion channels has widely been modeled by assuming the transition between open and closed states is a memoryless process. Nevertheless, the statistical analysis of an ionic current signal recorded from voltage dependence K+ single channel is presented. Calculating the sample autocorrelation function of the ionic current based on the digitized signals, rather than the sequence of open and...
Ion channels bear the same relation to electrical signaling in nerve, muscle, and synapse as enzymes bear to metabolism. The potassium channel is one of the most important type. Potassium ion is at least 10,000 times more permeant than sodium ion, remaining to be an open question of potassium channels. To elucidate the mechanism of ion selectivity at atomic level, the authors performed density functional...
We have detected synchronized spontaneous Ca2+ spikes in cultured cortical networks in the presence of Mg2+. The synchronized spontaneous Ca2+ spikes are synaptically driven, as it is blocked by tetrodotoxin (TTX), and by the glutamate receptor antagonist CNQX/APV. The oscillatory activity is not influenced by GABA A receptor antagonist picrotoxin, suggesting that they entirely rely on glutamatergic...
Epidemiological data suggest that the incidence of cardiovascular disease is reduced in people who have a high intake of phytoestrogens. The plant-derived estrogen biochanin A is known to cause vasodilation, but its mechanisms of action remain unclear. This study was undertaken to investigate the effects and mechanisms of biochanin A on rat thoracic aorta. Isolated aortic rings were suspended in individual...
The objective of this study was to determine whether the mitochondrial permeability transition pore plays a role in cardioprotection induced by tanshinone IIA. Isolated rat hearts were subjected to 30 min regional ischemia by ligation of the left anterior descending artery followed by 120 min reperfusion. Ischemic preconditioning (IPC) was achieved by two 5-min periods of global ischemia separated...
Heart failure has been identified as a serious international problem, in particular for aging groups, posing both an increasing number of patients on waiting lists in countries susceptible with Medicare systems and increasing financial burdens. It may be imperative to develop a marker that can identify such problems at an early stage. It is believed that certain proteins have crucial roles in early...
The work here presents an abnormal EEG simulation and an analysis for the abnormal spikes in the simulation by using the wavelet method. The simulation is derived from the electrophysiological model of an excitable neuron being in a disorder process. The spike wave and the multi-spike wave of the EEG morphology are reconstructed by step changes in the concentration of the intracellular calcium ions...
To find a better strategy for effective donor organ preservation, here we used a model of long-term hypothermia preservation of rat hearts to investigate the cardioprotective effects of diazoxide, a selective opener of mitochondrial ATP-sensitive potassium channel (mitoKATP ). Cardiac function was impaired by 8-hour ischemic preservation following 30 minutes of reperfusion. Treatment with diazoxide...
Nerve conduction block induced by high frequency biphasic electrical current was simulated using a lumped circuit model of the myelinated axon based on Frankenhaueuser-Huxley (FH) equations. Axons of different diameters (5-20 mum) can be blocked completed when the stimulation frequency is above 10 kHz. At higher frequency a higher stimulation intensity is needed to block nerve conduction. Larger diameter...
The purpose of this study was to investigate the effect of cyclosporin A on swelling amplitude and time constant of mitochondria isolated from normal and ischemic rat brain and to observe the possible role of the mitochondrial ATP-sensitive potassium channel on mitochondrial permeability transition. Mitochondrial swelling was evaluated by spectrophotometry. Cyclosporin A at 0.5 or 1 microM and diazoxide...
The variation of cell trans-membrane voltage exposed to extremely low frequency (ELF) electric field is analyzed; a modified Hodgkin-Huxley model of muscle (HHM) is established by introducing a new parameter denoting the effect of external electric field, and the bifurcation caused by the new parameter as well as leakage conductance and sodium ions anti-electromotive force is studied. The algebra...
Nano-selenium, a novel nano technology production, was demonstrated to be useful in medical and scientific researches. Here, we investigated the effects of nano-Selenium on tetrodotoxin-sensitive (TTX-S) voltage-dependent Na+ channels in isolated rat dorsal root ganglion neurons, using whole-cell patch-clamp method. Nano-selenium irreversibly decreased TTX-S Na+ current (INa) in a concentration-dependent...
We report that basic fibroblast growth factor (bFGF) induces the release of glutamate in ES-derived neurons during early stages of differentiation. Changes of Ca2+ concentration labeled by fluorescence intensity occurred in response to minimal concentrations of glutamate. The Ca2+ concentration was changed more rapidly by bFGF than by glutamate during the early stages of differentiation of ES-derived...
To test, analyze and express the relationship between the pharmacological effect of traditional chinese medicine (TCM) dragon's blood and that of its component loureirin B, specify an operational definition for effective component from raw drug of TCM. Using the whole-cell patch-clamp technique, the effects of dragon's blood and its component loureirin B on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant...
A system where model parts can be easily exchanged and modified is of great advantage, especially in a combination of models such as an electrophysiological cell model and a mechanical model to a more complex left ventricular (LV) motion model. The use of a distributed simulation environment is straightforward because each simulation model is calculated by an existing user-friendly simulator. However,...
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