title: Moderate elevation of extracellular potassium transiently inhibits regeneration of sensory axons in cultured adult sciatic nerves.
abstract: The adult frog dorsal root ganglia (DRG) together with the sciatic nerve (ScN) has previously been shown to survive in organ culture for several days. If a local test crush is made at the beginning of culturing, there is an initial delay of about 3 days before the sensory axons start to grow into the distal nerve stump at a rate of about 0.6-0.9 mm/day. The present results showed that axonal growth was unaffected in preparations maintained for 8 days in medium containing 10 mM K+ (5 mM is the physiological level). In contrast, the outgrowth was markedly reduced by 15 mM K+ and still more by 20 and 25 mM K+. The growth inhibition was partially counteracted by nifedipine, a Ca(2+)-channel antagonist. Other experiments clearly showed that high K+ exerted its effects during the early phase of the regeneration and lacked effects at later stages. The possibility that Ca(2+)-binding proteins, e.g. calbindin, which showed immunohistochemical reactivity in different structures, contribute to the growth adaptation to high K+ will be considered. The generality of the findings was supported by inhibition of axonal outgrowth of adult mouse sciatic sensory axons by high K+.
authors.affiliation: Department of Animal Physiology, University of Lund, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Edström
authors.forename: P
authors.initials: P
authors.lastname: Ekström
authors.forename: P
authors.initials: P
authors.lastname: Wiklund
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D001369:Axons / Q000502:physiology*; D064026:Calbindins; D002478:Cells, Cultured / Q000502:physiology; D007150:Immunohistochemistry; D009416:Nerve Regeneration / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000276:immunology; D009543:Nifedipine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D011896:Rana temporaria; D064030:S100 Calcium Binding Protein G / Q000032:analysis / Q000276:immunology; D012584:Sciatic Nerve / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D013997:Time Factors
chemical_list: D064026:Calbindins; D009419:Nerve Tissue Proteins; D064030:S100 Calcium Binding Protein G; D009543:Nifedipine; D011188:Potassium