Abstract
The mechanisms underlying resealing of transected myelinated rat dorsal root axons were investigated in vivo using an assay based on exclusion of a hydrophilic dye (Lucifer Yellow-biocytin conjugate). Smaller caliber axons (<5μm outer diameter) resealed faster than larger axons. Resealing was Ca2+ dependent, requiring micromolar levels of extracellular [Ca2+] to proceed, and further accelerated in 1mM Ca2+. Two hours after transection, 84% of axons had resealed in saline containing 2mM Ca2+, 28% had resealed in saline containing no added Ca2+ and only 3% had resealed in the Ca2+ buffer BAPTA (3mM). The enhancing effect of Ca2+ could be overcome by both non-specific cysteine protease inhibitors (e.g., leupeptin) and inhibitors specific for the calpain family of Ca2+-activated proteases. Resealing in 2mM Ca2+ was not inhibited by an inhibitor of phospholipase A2. Resealing in low [Ca2+] was not enhanced by agents which disrupt microtubules, but was enhanced by dimethylsulfoxide (0.5-5%).These results suggest that activation of endogenous calpain-like proteases by elevated intra-axonal [Ca2+] contributes importantly to membrane resealing in transected myelinated mammalian axons in vivo. Copyright (C) 1999 IBRO.
Original language | English (US) |
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Pages (from-to) | 807-815 |
Number of pages | 9 |
Journal | Neuroscience |
Volume | 93 |
Issue number | 2 |
DOIs | |
State | Published - Jul 1999 |
Keywords
- Axon
- Calcium
- Calpain
- Dimethylsulfoxide
- Mechanical injury
- Membrane resealing
ASJC Scopus subject areas
- Neuroscience(all)