1991 Fiscal Year Final Research Report Summary
Dynamic morphological change of Schwann cells and nerve impulse modulation.
| Project/Area Number |
01480545
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
生物物性学
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| Research Institution | Okazaki National Research Institutes |
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Principal Investigator |
KUKITA Fumio Okazaki National Research Institutes, Natl Inst for Physiol. Sci., Research Associate, 生理学研究所, 助手 (40113427)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Schwann cells / Nerve fiber / Nerve impulse / Potassium Regulation / Brain microenvironment |
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| Research Abstract |
The mechanism of a brain microenvironment regulation with glial cells have been studied in the Squid Axon-Schwann cell preparation as a simplest model. The condition of Schwann cells including the mormophology and their ion permeability can be changed easily in the squid axon-Schwann cell preparations. The following results were obtained in this preparation.
1)The periaxonal potassium accumulation in the narrow space between the axon and the Schwann cell layer can be decreased by the outward osmatic gradient and increased by the inward osmotic gradient which were applied across the axon inside and the outside of the Schwann cell layers.
2)When the external potassium concentration, in which the Schwann cells were bathing, was increased, the periaxonal potassium accumulation increased. The model analysis showed that raising the extemal potassium concentration caused the Schwann cell volume increase and the decrease in the potassium permeability of the Schwann cell layer.
3)The response of the axon by the repetitive stimulation is altered by the change in the condition of Schwann cells. In the condition of the large periaxonal potassium accumulation, the threshold of the nerve activity increased, there appeared an irregular firing pattern. This can be demonstrated also in a computer simulation with a modified Hodgkin-Huxley equation.
4)In the physiological condition, the condition of Schwann cells could be changed during the nerve activity and there is a possible mechanism of the communication between axon and Schwann cells with potassium ions and some chemical transmitters. These interesting theme continued to be studied in the Japanese and British International Research Project of Mollusca neurophysiology.
5)The effects of drugs including anesthesia are intensively studied, because the effects of nerve fiber preparation should be separated into the effects on the axon and those on the Schwann cells.
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