Enhancement of veratridine-induced sodium dynamics in NG108-15 cells during differentiation.
Developmental changes in dynamics of Na+ were studied in neuroblastomaxglioma hybrid NG108-15 cells during differentiation which was induced by dibutyryl cAMP (Bt2cAMP). Ratiometric Na+ imaging with a Na+-sensitive fluorescent dye SBFI (sodium-binding benzofuran isophthalate) revealed that the intracellular Na+ concentration ([Na+]i) was not affected by the application of high K+ (60 mM) solution to either control or differentiated cells. When cells were exposed to 50 microM veratridine (Vtd), an agonist of voltage-sensitive sodium channels (VSSCs), a significant increase in [Na+]i was observed in differentiated but not in undifferentiated cells. Calculated mean [Na+]i value increased from the basal 10.4 to 44.1 mM in response to 50 microM Vtd. This Vtd response was reversibly inhibited by tetrodotoxin (TTX), a specific blocker for VSSCs, in a dose-dependent manner (IC50 = 1 nM). It is suggested that VSSCs in NG108-15 cells are sensitive to TTX and Vtd and that the number of VSSCs increases during differentiation.
Imanishi
Takashi
T
Department of Biological Chemistry, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashiosaka, Japan.
Matsushima
Kayoko
K
Kawaguchi
Akinori
A
Wada
Tetsuyuki
T
Masuko
Takashi
T
Yoshida
Shigeru
S
Ichida
Seiji
S
D001572:Benzofurans; D003994:Bucladesine / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004988:Ethers, Cyclic; D005456:Fluorescent Dyes; D006801:Humans; D009474:Neurons / Q000187:drug effects; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*; D062687:Sodium Channel Agonists; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology*
D001572:Benzofurans; D004988:Ethers, Cyclic; D005456:Fluorescent Dyes; D062687:Sodium Channel Agonists; D026941:Sodium Channel Blockers; C061665:sodium-binding benzofuran isophthalate; D013779:Tetrodotoxin; D003994:Bucladesine; D014701:Veratridine; D012964:Sodium; D011188:Potassium