[Structural changes in spinal cord neurons after low-intensity SHF-irradiation].

On anaesthetized cats carried out local irradiation by super high frequence waves (SHF) on spinal cord (SC) at a level L6-S1 of segments (lambda = 3 sm, power from 1 up to 3 mWt/sm2, time of an exposition--20 or 30 minutes). The sections of a brain painted with application of hematoxylin-eosin. The received images was studied on light microscope and were analyzed on the computer. On motho- and interneurones SC it is revealed, that such parameters as nucleus--cytoplasm relation and relation of volume of cytoplasm to surface of a nucleus are subject to the greatest influence. The effect of application are maximal during the small period after an irradiation (1-2 hours). Received results can testify on change of character of processes of a metabolism between a nucleus and cytoplasm, infringement of creation of neurotransmitter and decreasing of membrane potential of nervous cells and axons.

[The change of negative components of the evoked potentials of spinal cord after irradiating of a SHF-waves].

The influence of super high frequency (SHF) waves (lambda = 3 sm) nonthermal intensity (1.6 mWt/sm2) on work of regulator systems of a spinal cord (SC) of cats was considered. The estimation of parameters of negative components of cord dorsum potential (CDP) is made for stimulus, which apply on peripheral nerves or dorsal root earlier and after the influence of SHF on SC. Change in work of population of segmentary and non-segmentary interneurons after the SHF irradiation with 30 minutes exposition was shown. The authors consider that the main influence SHF waves is directed on a changes of membrane potential of SC neurons. The specified effect carries temporary and convertible character.

[The effect of their initial functional status on the radiation reaction of the neurons in the rat spinal cord]. / Vliianie iskhodnogo funktsional'nogo sostoianiia na luchevuiu reaktsiiu neironov spinnogo mozga krysy.

The influence of CNS functional state and structural changes of neurons in spinal cord following local exposure to 38 or 76 Gy X-radiation. Morphological analysis show, that stimulation of peripheral nerves increase, but hypoxia or barbiturates decrease destruction of spinal neurons by radiation. Value destruction also depends of neurons volumes.

[Changes in the spinal cord potentials of the rat in whole-body irradiation at a dose of 360 Gy]. / Izmeneniia potentsialov spinnogo mozga krysy pri total'nom obluchenii v doze 360 Gr.

In acute experiments in rats the effect of the whole-body X-irradiation with a dose of 360 Gy on induced somatosensory spinal cord potentials (SCP) was studied. The SSP components which show decrease in intensity and period depending upon a dose and time after irradiation were determined. The destruction of spinal input control systems was found. The causes and possible pathways of neuronal response depression which is probably due to synaptic structure damage have been considered. It is assumed that spinal potentials can be used as additive index of the extent of reaction to irradiation.

[Contribution of antidromic activity, induced by excitation of efferent fibers, to massive potentials of the cat spinal cord]. / Vklad antidromnoi aktivnosti, vyzyvaemoi vozbuzhdeniem éfferentnykh volokon, v massovye potentsialy spinnogo mozga koshki.

Biphasic cord dorsum potentials (CDP) were evoked on the cat spinal cord by stimulation of the distal stump of a cut ventral root (V-CDP) or peripheral nerves (N-CDP) with the cord deafferentation in L5-S1 segments. Measurements of their latency and the threshold in the responsible efferent fibres have shown that they were produced mainly by the activity of the low-threshold fibres in the ventral root. Stimulation of peripheral nerves with cord deafferentation has demonstrated a change in the amplitude of the positive presynaptic component of the "standard" CDP. Application of double stimuli on dorsal and ventral inputs has elicited two maxima of V-CDP depression. This depression is connected with developed orthodromic mono- and polysynaptic reflexes in motoneurons. The data obtained confirm that the investigated V-CDP is a component part of the "afferent" spike of standard CDP evoked by stimulation of intact nerves. Such data for main hindlimb nerves of the cat are adduced. A conclusion is drawn that integrity of efferents may be determined by analysis of presynaptic spikes of CDP.

[The effect of SHF waves on the evoked potentials in the cat spinal cord]. / Vliianie voln SVCh na vyzvannye potentsialy spinnogo mozga koshki.

In experiments with adult cats there revealed a pronounced effect of SHF radiation on the electrogenesis of spinal cord, the beam density being 15 mW/cm2 and time of exposure 10 min. The estimates of the induced somatosensory brain potentials indicate that there is a phase of a 20 per cent response inhibition with the effect reaching maximum 2-3 h following irradiation. Subsequently, potential characteristics are exponentially restored to be the same with the control values. The evidence is presented that the synaptic neuron contacts within the reflex arc are highly susceptible to SHF radiation.

[A biosynchronization unit for electrophysiologic studies of the brain]. / Ustroistvo biosinkhronizatsii dlia élektrofiziologicheskikh issledovanii mozga.

Under registration and accumulation of the spinal cord potentials from the surface of the body, the use was made of biosignals (ECG) which trigger the computerised analysing system. The proposed machine uses ECG as the synchronised signal. The principles of its work and scheme are given as well.

[The role of homosynaptic depression in stabilizing spinal cord potentials]. / Rol' gomosinapticheskoi depressii v stabilizatsii potentsialov spinnogo mozga.

A decrease of variation coefficient for the amplitudes of dorsal root potentials and cord dorsum potentials (CDP) was found in anaesthetized spinal cats. Reduction of the number of spikes in neurons, which are suggested to take part in generation of CDP in response to repetitive stimulation of cutaneous nerves was also seen. A maximum decrease of variation coefficient was observed at low frequency of stimulation (0.1-5 Hz). The effects observed can be due to homosynaptic depression.

[Changes in antidromal discharges in the peripheral nerves in the cat in response to polarization of the spinal cord by a steady current]. / Izmenenie antidromnykh razriadov v perifericheskikh nervakh koshki pri poliarizatsii spinnogo mozga postaiannym tokom.

The influence of constant current passing through the spinal cord cross-section on the antidromic discharges in afferent nerves caused by intraspinal stimulation of central afferent terminals was studied in experiments on anasthetized cats. The current flowing through the spinal cord in the dorso-ventral direction produced an increase or antidromic discharges. The current flowing in the ventro-dorsal direction produced an opposite effect. Facilitation of antidromic discharges evoked by conditioning stimuli decreased with an increase of constant current of both directions. It is suggested that depolarizing shift of the membrane potentials of afferent terminals occurs when the current flows in the dorso-ventral direction. the situation reverses when the direction of current flow becomes opposite.