Dissection of bradykinin-evoked responses by buffering intracellular Ca2+ in neuroblastoma x glioma hybrid NG108-15 cells.
Signal transduction pathways from bradykinin (BK) receptors were investigated in NG108-15 neuroblastoma x glioma hybrid cells by buffering the intracellular calcium (Ca2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a Ca2+ chelator. BK increased inositol-1,4,5-trisphosphate (Ins(1, 4,5)P3) formation at the same rate in the control and in BAPTA-acetoxy methyl ester (AM)-treated NG108-15 cells. However, a transient increase of intracellular Ca2+ concentrations in response to BK was significantly suppressed in Ca(2+)-buffered hybrid cells. Accordingly the BK-induced outward current was inhibited in BAPTA-AM-treated hybrid cells, while the subsequent inward current associated with a fall in membrane conductance was apparently increased. The initial phase of acetylcholine release from NG108-15 cells in response to BK was markedly inhibited in BAPTA-AM-treated coculture dishes when detected as miniature end-plate potentials of myotubes, though the late phase of acetylcholine secretion was observed. These results indicate that BK induces two distinct responses in NG108-15 cells: Ins(1,4,5)P3-dependent intracellular Ca2+ rise-sensitive and -insensitive components.
Kimura
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Y
Department of Biophysics, Kanazawa University School of Medicine, Japan.
Higashida
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H
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002021:Buffers; D002118:Calcium / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004594:Electrophysiology; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006822:Hybrid Cells; D007425:Intracellular Membranes / Q000378:metabolism*; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D009994:Osmolar Concentration; D051381:Rats; D013569:Synapses / Q000187:drug effects; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
D002021:Buffers; D004533:Egtazic Acid; D010738:Type C Phospholipases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D001920:Bradykinin; D002118:Calcium