Sodium channels in the cytoplasm of Schwann cells

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.87.23.9290· OSTI ID:5031278

Ritchie, J M ^[1]; Black, J A; Waxman, S G ^[2]; Angelides, K J ^[3]

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1. Yale Univ. School of Medicine, New Haven, CT (United States)
2. Yale Univ. School of Medicine, New Haven, CT (United States) Veterans Affairs Medical Center, West Haven, CT (United States)
3. Baylor College of Medicine, Houston, TX (United States)

Immunoblotting, ultrastructural immunocytochemistry, and tritiated saxitoxin (({sup 3}H)STX) binding experiments were used to study sodium channel localization in Schwann cells. Polyclonal antibody 7493, which is directed against purifed sodium channels from rat brain, specifically recognized a 260-kDa protein corresponding to the {alpha} subunit of the sodium channel in immunoblots of crude glycoproteins from rat sciatic nerve. Electron microscopic localization of sodium channel immunoreactivity within adult rat sciatic nerves reveals heavy staining of the axon membrane at the node of Ranvier, in contrast to the internodal axon membrane, which does not stain. Schwann cells including perinodal processes also exhibit antibody 7493 immunoreactivity, localized within both the cytoplasm and the plasmalemma of the Schwann cell. To examine further the possibility that sodium channels are localized within Schwann cell cytoplasm, ({sup 3}H)STX binding was studied in cultured rabbit Schwann cells, both intact and after homogenization. Saturable binding of STX was singificantly higher in homogenized Schwann cells than in intact Schwann cells. Moreover, the equilibrium dissociation constant was higher for homogenized preparations (1.77 {plus minus} 0.37 nM) than for intact Schwann cells (1.06 {plus minus} 0.29 nM). These data suggest the presence of an intracellular pool of sodium channels or channel presursors in Schwann cells.

• OSTI ID: 5031278
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (United States) Vol. 87:23; ISSN 0027-8424; ISSN PNASA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ANIMAL CELLS
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
CHEMISTRY
CYTOCHEMISTRY
DOSE-RESPONSE RELATIONSHIPS
ELECTRON MICROSCOPY
GLYCOPROTEINS
HYDROGEN COMPOUNDS
KINETICS
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
MICROSCOPY
NERVE CELLS
ORGANIC COMPOUNDS
PROTEINS
REACTION KINETICS
SODIUM COMPOUNDS
SOMATIC CELLS
TRANSMISSION ELECTRON MICROSCOPY
TRITIUM COMPOUNDS
UPTAKE