Effect of electric stimulation of non-specific and specific thalamic nuclei on the spatial synchronization of cortical potentials in the rabbit

The effect of low-frequency (1-10 Hz) electrical stimulation of nonspecific n. centralis lateralis and n. centrum medianum and specific thalamic (LGB) nuclei on spatial synchronization of biopotentials of neocortical areas and on the process of learning was studied on rabbits. Electrical stimulation of the non-specific nuclei raised the level of correlation of the cortical potentials, while the LGB stimulation, on the contrary, weakened the spatial synchronization between the potentials of the visual and sensorimotor neocortical areas. On the basis of the obtained data a conclusion is made that stimulation of the non-specific thalamus contributes to a more successful formation of defensive conditioned reflex to light unlike LGB stimulation. It is suggested that a certain specificity of the studied subcortical formations in organization of spatial synchronization of the brain biopotentials and in the process of learning is due to morpho-functional peculiarities of these structures.     

Effect of heart electric stimulation on repolarization of ventricular myocardium of fish and amphibians

The distributions of repolarization durations and end of repolarization time were studied on the ventricular epicardium in pikes (Esox lucius) and frogs (Rana esculenta) and in the ventricular intramural layers in toads (Bufo bufo) at the ectopic heart excitation by using method of the synchronous multielectrode cartography (24 unipolar leads). The time of arrival of the excitation wave and the end of repolarization in each lead were determined from the minimum of time derivative of potential at the period of QRS complex and by minimum of T wave, respectively. It has been established that at the ventricle electrostimulation, alongside with deceleration and a change of sequence of myocardium activation, the redistribution occurs of the local durations of repolarization, being longer than in zones of early activation (p < 0.05). At stimulation, the apicobasal gradient of repolarization is predominantly changed due to electrophysiological processes in the apical areas. In all the studied species, at the ectopic excitation of the heart the sequence of its repolarization repeats the depolarization sequence due to a delay of activation (in fish) and redistribution of repolarization durations (in amphibians).     

An extra atrioventricular node in an anomalous heart of a calf

An extra atrioventricular node in a double outlet ventricle with a quite normal inflow septum in a calf is described. The anomaly resembles the topography of the conducting system in the calf heart in the embryonic stages from 13.5 mm-90 mm.     

Effect of electric stimulation of auricular acupuncture points on H-reflex

The non-nociceptive H-reflex in the musculus soleus were recorded before and after auricular electroacupuncture (AEAP) in patients with vertebrogenic pain syndrome. Changes of the H-reflex on the side of the pain syndrome were observed after ipsi- and contralateral AEAP, the latter producing effect more often. Changes of H-reflex are mainly of facilitating character (71.4%) and, rarely, of inhibitory character (14.3%). In the part of patients AEAP produced distinct facilitation of M-response.     

Electrophoretic characteristics of nuclear proteins in the rat liver after electric stimulation of the hypothalamus

The liver nuclear proteins of 3- and 6-month old rats were studied by the gel-electrophoresis technique after electrostimulation of hypothalamus. In this case new nuclear proteins with low molecular weight were found. The electrophoretic rate of these proteins is higher than that of histone H4. A decrease in the content of histone H2B in the nuclear liver of 6-month old rats was also found after electrostimulation of hypothalamus. The mechanism of this phenomenon is discussed.     

Bacteriorhodopsin (BR570) bathochromic band shift in an external electric field

In dry films of bacteriorhodopsin-containing purple membranes from Halobacterium halobium the external electric field (10⁴–10⁵ V · cm^?1) induces the appearance of a product spectrally close to the initial intermediate of bacteriorhodopsin (BR) photochromic cycle (batho form, K). This result and also preliminary data of the electret-thermal analysis of the preparations suggest that the dielectric polarization in chromophore-protein-lipid complexes might be an essential step of the primary stabilization of light energy in photo-bioenergetic processes.     

电刺激迷走神经对蟾蜍心率和心率变异的影响

目的:观察不同频率迷走神经刺激对蟾蜍离体心脏的心率及心率变异的影响。方法:将蟾蜍心脏和右侧迷走交感干离体后,以不同频率电刺激神经,记录心电图曲线并作心率变异性(HRV)分析。结果:交感神经阻断后,电刺激迷走交感干,心率(HR)显著下降(P0.01),全部正常心动周期的标准差(SDNN)和相邻正常心动周期差值的均方根(RMSSD)显著升高(P0.01),不同频率刺激组之间没有明显差异;与对照组相比,各指标变化较大;给药组0.2Hz时高频(HF)显著升高(P0.01),低频/高频比值(LF/HF)明显降低(P0.05),0.8Hz时HF和LF/HF接近刺激前水平。结论:一定范围内增加刺激频率,迷走神经降低心率的作用增强;没有交感神经调节条件下的迷走神经对心率和心率变异的调节可能存在不同的机制。     

Frequency-dependent effects in an alternating electric field on an isolated frog heart

An isolated frog heart placed in a special chamber with Ringer solution (pH 7.2) was stimulated by electric field at a frequency of 0.3-4.0 Hz with graphite electrodes immersed in the solution. Unusual resonance phenomena were observed during a progressive increase or decrease of the stimulation frequency: the amplitude of the mechanical responses of the preparation rose at multiple frequencies of stimulation, whereas the frequency of the responses remained unchanged.