| Project/Area Number |
59570068
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Neurophysiology and muscle physiology
|
|---|
| Research Institution | Gifu University (1986)
Kanagawa Dental College (1984-1985) |
|---|
Principal Investigator |
ONOZUKA Minoru Gifu University School of Medicine, 医学部, その他 (90084780)
|
|---|
| Project Period (FY) |
1984 – 1986
|
| Project Status |
Completed (Fiscal Year 1986)
|
| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1986: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1985: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1984: ¥1,100,000 (Direct Cost: ¥1,100,000)
|
|---|
| Keywords | Glial cell / <Na^+> - <K^+> pump / potassium / sodium / ATPase activity / cerebral cortex |
|---|
| Research Abstract |
The characteristics of a glial <Na^+> - <K^+> pump dependent on extracellular <K^+> within epileptogenic cortex were studied electrophysiologically, biochemically and histochemically in vitro using slices from either cobalt- or kainic acid-induced epileptogenic cortex of rat. When the extracellular <K^+> concentration ([ <K^+> ]) was varied between 4 and 40 mM, the mean slope of membrane potential plotted against <[K^+]+o> was about 57 mV in glia from the normal cortex (tissue A) and about 44 mV in glia from the epileptogenic cortex (tissue B); whereas no significant difference in the resting membrane potential of these tissues was observed. In glia from tissue B, a marked transient hyperpolarizarion above control level was caused by replacement of elevated <[K^+]_o> with the normal medium. Ouabain abolished these phenomena observed in glia from tissue B, but had no effect on the membrane potential during normal <[K^+]_o> . Reduction of extracellular <Na^+> , <Ca^(2+)> and <Cl^-> did not significantly affect the membrane potential of glia from either tissue, In tissue A, the cells marked by intracellular injection of horseradish peroxidase after intracellular recording were protoplasmic astrocytes; in tissue B, fibrous astrocyte with abnormal processes predominated. <K^+> -dependent stimulation of ( <Na^+> , <K^+> )-ATP-ase activity of the astrocyte-enriched fraction and its membrane preparation from tissue B was much larger than that from tissue A. A certain amount of the reaction product of <K^+> -pNPPase activity was seen on glial plasma membrane within tissue B but not on that from tissue A. These results suggest that epileptogenic cortex may be modified to increase in its activity.
|
