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Postnatal Changes in Enzyme Activities in Synaptosomes Isolated from Hamster Optic Nerve Endings
Author(s) -
Specht Susan C.
Publication year - 1982
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1982.tb03948.x
Subject(s) - cytochrome c oxidase , free nerve ending , hamster , enzyme , synaptosome , mitochondrion , biology , golden hamster , enzyme assay , biochemistry , inner mitochondrial membrane , chemistry , endocrinology , membrane
Abstract: Subsynaptosomal fractions isolated from optic terminal nuclei of adult and neonatal hamsters exhibited developmental changes in specific density, mitochondrial activity, and K + ‐stimulated, ouabain‐inhibited p ‐nitrophenylphosphatase (K‐pNPPase) activity around the time of eye opening. The specific activity of K‐pNPPase was six‐ to sevenfold higher after eye opening (14–16 days postnatal). A significant proportion of high‐specific‐activity K‐pNPPase was recovered from the lightest subsynaptosomal fraction at all ages. This fraction contained very little external membrane by galactose oxidase–NaB 3 H 4 labeling, suggesting that it may represent an internal pool, possibly the axonally transported form of the enzyme. Synaptic mitochondrial cytochrome c oxidase activity also approximately doubled in the period between 12 and 16 days. The specific density of the external membrane increased more slowly, banding at 1.0 M sucrose at 12 and 16 days, and at 1.2 M in adults. These maturational events may reflect increased energetic needs of optic nerve endings following eye opening.