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Increased Depolarization‐Induced Cytosolic CA 2+ Signal In Rat Dorsal Root Ganglion Neurons Under High Glucose With Suppressed NA + /K + Pump Activity
Author(s) -
Sanada M,
Yasuda H,
OmatsuKanbe M,
Matsuura H,
Kikkawa R.
Publication year - 2000
Publication title -
journal of the peripheral nervous system
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 67
eISSN - 1529-8027
pISSN - 1085-9489
DOI - 10.1046/j.1529-8027.2000.005003179.x
Subject(s) - depolarization , dorsal root ganglion , ouabain , chemistry , biophysics , cytosol , medicine , endocrinology , calcium , sodium , biochemistry , dorsum , anatomy , biology , enzyme , organic chemistry
Hyperglycemia and its associated Na + /K + pump activity has been implicated in the development of diabetic neuropathy. We recently reported that high glucose in the presence of ouabain induced a progressive increase in the delayed K + current which was suppressed by a blocker of Ca 2+ ‐activated K + channels and blockers of Ca 2+ channels in rat single myelinated nerve fibers, suggesting an increase of cytosolic free Ca 2+ concentration ([Ca 2+ ] i ). However, the influences of high glucose with ouabain on [Ca 2+ ] i in sensory neurons remain to be elucidated. The present study was undertaken to examine the modulation of depolarization‐induced Ca 2+ transients by high glucose and ouabain in isolated adult rat dorsal root ganglion (DRG) neurons using the fluorescent Ca 2+ indicator fura‐2. Bath application of KCl (50 mM) evoked a rapid increase in [Ca 2+ ] i through voltage dependent Ca 2+ channels ([Ca 2+ ] i : 154.2 ± 22.5 nM). This increase was enhanced under high glucose (30 mM D‐glucose) in the presence of ouabain (100 M) ([Ca 2+ ] i : 764.8 ± 210.1 nM). We conclude that a combination of high glucose and decreased Na + /K + pump activity leads to an increase in [Ca 2+ ] i in rat DRG neurons, thereby resulting in nerve dysfunction.