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Biomedical subjects

O S Merkulova

Publications and source records attributed to O S Merkulova.

9 recordsLinked to original sources
PubMed1979

[Bioelectrical activity and ultrastructure of medicinal leech Retzius neurons during chronic direct and synaptic activation].

The threshold direct or synaptic 1/sec stimulation of the Retzius cells increases the firing rate of the neuron in the leach. The firing rate becomes synchronized with the stimulation applied. The membrane potential does not change. After 10 min of such stimulation changes occurring in the ultrastructure of neuron are similar to those in a neuron with no stimulation: these changes reveal a decrease in the synthetic processes whereas the bioelectrical activity remains the same which suggests a certain independence of the neuron electrophysiological parameters of its ultrastructure.

Animals↗
PubMed1978

Effect of hydrocortisone on bioelectric activity and morphological pattern of spinal cord in frogs.

The effect of 1 mg hydrocortisone (HC) administered 3 h before the experiment was studied the bioelectric activity of ventral roots of spinal cord, the size and morphology of motoric neurons and also the size of synaptic endings being measured under different frequency of electric stimulation in frogs. It was found that the effect of HC on the electric activity of spinal cord and morphology of its neural elements was dependent on the stimulation used. Under the resting conditins the administration of HC resulted in a small decrease of the size of neurons. Under a low frequency stimulation HC did not affect the electric activity of spinal cord, but prevented the swelling of neurons and of synaptic endings resulting from the stimulation. Under a high frequency stimulation themorphology of neurons was remarkably changed, a shrinkage of these and an appearance of "dark" cells being found. Also these changes were prevented by the administration of HC. It was concluded that in all experiments HC prevented the changes resulting from electrostimulation, its effect, however, being dependent on the parameters of the stimulation used.

Animals↗
PubMed1978

[Characteristics of synaptic and intracellular neuron activation].

Stimulation of the leech abdominal neural chain with electric pulses of 1 imp/sec frequency results in alterations in the activity of the Retzius cells in addition to an increased protein metabolism in the postactivation period. The direct stimulation produces a decrease in the cellular protein metabolism.

Abdomen↗
PubMed1976

[Strength of synaptic stimulation and morpho-functional reorganization of the neuron].

In the Retzius cell of the leech, synaptic threshold and three-fold threshold stimulation 1/sec was followed by readjustment of the cell spike activity according to the stimulation rhythm. After cessation of the stimulation the initial bioelectrical activity restores. The membrane potential remains unaltered during the three-fold threshold stimulation. Electron-microscopically, the Retzius cells develop different ultrastructural changes. In case of the threshold stimulationthe changes indicate an intensification of the synthetic processes and, on the contrary, the three-fold threshold stimulation is followed by a decrease in the proteinmetabolism. In the first case, the amount of granular endoplasmatic reticulum increases and in the second case -- decreases. The same is true for the total amount of ribosomes. During synaptic stimulation, the Retzius cell mitochondria remain unlatered while during the three-fold threshold stimulation the mitochondria swell, their matrix clears up, and their krysts become reduced.

Animals↗
PubMed1976

[The influence of synaptic processes on changes in neuronal structure].

Reactions of the spinal motoneurons to the afferent inflow were different in frogs: some neurons generated spike potentials during 10-min rhythmic stimulation (1/sec) of afferents, other neurons were switched on and off. The motoneurons and their synapses increased in size, their cytoplasmic matrix became lighter and ribosoms deteriorated. Antidromic activation did not entail modofocation of size or color of the cells. RNP granules were safe and local organellas degenerated. The role of synaptic processes in regulation of RNP metabolism and in intracellular reparation, was revealed.

Animals↗