Jt. Bartrup et Nr. Newberry, 5-HT2A RECEPTOR-MEDIATED OUTWARD CURRENT IN C6 GLIOMA-CELLS IS MIMICKED BY INTRACELLULAR IP3 RELEASE, NeuroReport, 5(10), 1994, pp. 1245-1248
THE C6 glioma cell line possesses 5-HT2A receptors that have been show
n to increase intracellular calcium levels. We have studied the electr
ophysiological response of these cells to 5-HT using the whole-cell re
cording method. Under voltage-clamp, 5-hydroxytryptamine (5-HT) produc
ed an outward current in these cells which was inhibited by extracellu
larly applied ketanserin and spiperone and by EGTA (10 mM) in the reco
rding electrode. The 5-HT induced response could be mimicked by intrac
ellular photolytic release of inositol (1,4,5) trisphosphate (IP3) fro
m caged molecules. The reversal potentials for the IP3- and 5-HT-induc
ed responses were closely matched. The data indicates that the outward
current is likely to be mediated by 5-HT2A receptors stimulating IP3
production which increases intracellular calcium leading to the openin
g of calcium-activated potassium channels.