Multiple actions of dimethylsphingosine in 1321N1 astrocytes.
N,N-dimethyl-D-erythro-sphingosine (DMS) is an N-methyl derivative of sphingosine and an inhibitor of protein kinase C (PKC) and sphingosine kinase (SK). In the present study, we examined the effects of DMS on intracellular Ca2+ concentration, pH, and glutamate uptake in human 1321N1 astrocytes. DMS increased intracellular Ca2+ concentration and cytosolic pH in a concentration-dependent manner. Pretreatment of the cells with the Gi/o protein inhibitor PTX and the PLC inhibitor U73122 had no obvious effect. However, removal of extracellular Ca2+ with the Ca2+ chelator EGTA or depletion of intracellular Ca2+ stores with thapsigargin impeded the DMS-induced increase of intracellular Ca2+ concentration. Pretreatment of cells with NH4Cl or monensin reduced the DMS-induced Ca2+ increase. However, inhibition of the DMS-induced Ca2+ increase with BAPTA did not influence the DMS-induced pH increase. DMS also inhibited glutamate uptake by the 1321N1 astrocytes in a concentration-dependent manner. It also increased intracellular Ca2+ and pH in PC12 neuronal cells. Our observations on the effects of DMS on 1321N1 astrocytes and PC12 neuronal cells point to a physiological role of DMS in the brain.
Lee
Yup-Kyung
YK
Laboratory of Pharmacology, College of Pharmacy and Research Institute of Drug Development, Pusan National University, Busan 609-735, Korea.
Kim
Hyo-Lim
HL
Kim
Yu-Lee
YL
Im
Dong-Soon
DS
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology; D002118:Calcium / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D016716:PC12 Cells; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
D018698:Glutamic Acid; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; C061800:N,N-dimethylsphingosine; D013110:Sphingosine; D002118:Calcium