Publication: Cytochemical localization of Na+/K+ -ATPase activity in cochlear strial marginal cells after various catecholamine administrations
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Date
2001
Authors
Kanoh, N. ; Dai, C.F. ; Mohri, D. ; Hori, S.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
Sodium/potassium-activated adenosine
triphosphatase (Na+/K+-ATPase) activity in the kidney
and brain is high, and is regulated by catecholamines.
Na+/K+-ATPase activity is also high in the basolateral
infoldings of the strial marginal cells, where it aids in
maintaining the characteristic electrolyte composition of
the endolymph. To clarify the involvement of humoral
control in strial function, particularly the role of
catecholamines, the K+-dependent p-nitrophenylphosphatase
(K+-NPPase) activity of strial marginal
cells was investigated in guinea pigs using a ceriumbased
cytochemical method. The effects of reserpine,
serotonin (5-HT), norepinephrine (NE), epinephrine
(EP), both alone and in combination, were studied. High
doses of reserpine cause depletion of sympathetic
substances. Stria1 K+-NPPase activity was decreased
after reserpine or dopamine treatment, and was increased
after 5-HT, NE, and EP treatment. After reserpinization,
repeated treatment with 5-HT, NE, or EP led to
detectable strial enzyme activity. Thus, exogenous 5-HT,
NE, and EP were able to restore strial K+-NPPase
activity in the reserpine-treated animals. These results
suggested that biogenic amines regulate strial K+-
NPPase activity. Thus, the function of the stria vascularis
may be regulated by the opposing actions of these
catecholamines, and 5-HT.
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