Cytosolic Ca2+ under high glucose with suppressed Na+/K+ pump activity in rat sensory neurons.
Cytosolic Ca2+ concentration ([Ca2+]i) was measured in isolated rat dorsal root ganglion (DRG) neurons using the fluorescent Ca2+ indicator fura-2. Exposure to high (50 mM) extracellular K+ evoked a robust increase in [Ca2+]i, which was almost totally abolished by concomitant presence of nisoldipine (10 microM) and omega-conotoxin GVIA (10 microM). Whereas either high (30 mM) D-glucose alone or ouabain (100 microM) alone did not appreciably affect the high K+-induced [Ca2+]i elevation, neurons pretreated with high D-glucose together with ouabain exhibited a significantly larger [Ca2+]i response to high K+ stimulation, which was almost completely inhibited by nisoldipine and omega-conotoxin GVIA. These results suggest that a combination of high glucose and suppressed Na+/K+ pump activity potentiates the [Ca2+]i elevation stimulated by activation of the voltage-gated Ca2+ channels in rat DRG neurons.
Sanada
Mitsuru
M
Division of Neurology, Department of Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
Matsuura
Hiroshi
H
Omatsu-Kanbe
Mariko
M
Sango
Kazunori
K
Kashiwagi
Atsunori
A
Yasuda
Hitoshi
H
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage*; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose; D002118:Calcium