Differential regulation of intracellular signaling systems by sodium fluoride in rat glioma cells.
We investigated the rapid and slow effects of NaF on intracellular signaling systems such as Ca2+ homeostasis and cyclic GMP (cGMP) generation in rat glioma C6 cells, using the Ca2+-sensitive dye fura-2 and cGMP enzyme immunoassay. We found that the following: (a) NaF enhanced cGMP generation in a concentration-dependent manner. This enhancement was abolished by pretreatment with 100 microM BAPTA tetraacetoxymethal ester or in the presence of W-7 in a concentration-dependent manner. N G-Monomethyl-L-arginine (NMMA), a competitive inhibitor or nitric oxide synthase (NOS), also inhibited the NaF-induced generation of cGMP. These results suggest that NaF-induced cGMP generation occurs via a calcium/calmodulin- and NOS-dependent pathway. (b) The basal intracellular Ca2+ concentration ([Ca2+]i) was transiently greater at 1 and 3 h after pretreatment with NaF. W-7 and W-13 antagonized the increase in [Ca2+]i, whereas NMMA had little effect. This suggests that the NaF-induced change in basal [Ca2+] was mediated by a calmodulin-dependent pathway but was independent of a NOS-sensitive pathway. (c) The serotonin (5-HT)-induced intracellular mobilization of Ca2+ was reduced by pretreating the cells with NaF. The reduction in Ca2+ mobilization was antagonized by genistein, a tyrosine kinase inhibitor. W-7, W-5, and H-8 had no effect. Results suggest that NaF differentially regulated the cGMP generation. basal [Ca2+]i, and 5-HT2A receptor function in C6 glioma cells.
Kagaya
A
A
Department of Psychiatry and Neurosciences, Hiroshima University School of Medicine, Japan.
Uchitomi
Y
Y
Kugaya
A
A
Takebayashi
M
M
Nagaoka
I
I
Muraoka
M
M
Yokota
N
N
Yamawaki
S
S
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents; D006152:Cyclic GMP / Q000096:biosynthesis / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005910:Glioma; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D012969:Sodium Fluoride / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine
D002614:Chelating Agents; D004791:Enzyme Inhibitors; D013449:Sulfonamides; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D012701:Serotonin; D004533:Egtazic Acid; C017967:W 7; D012969:Sodium Fluoride; D001120:Arginine; D006152:Cyclic GMP; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium