Ca2+-dependent K+ channels in neuroblastoma hybrid cells activated by intracellular inositol trisphosphate and extracellular bradykinin.
Bradykinin (BK) activation of phosphatidylinositide breakdown in NG108-15 neuroblastoma x glioma hybrid cells in the generation of an outward K+ current through the release of Ca2+ by the intermediary messenger inositol 1,4,5-trisphosphate (InsP3). Channels mediating this outward current were identified using cell-attached patch electrodes. Intracellular iontophoretic injection of InsP3 or Ca2+, or extracellular application of BK, evoked bursts of K+ channel activity coincident with cell hyperpolarization measured with an intracellular recording micropipette. The most frequent channels had a mean single-channel conductance of about 40 pS in symmetrical K+ solutions; additional openings of lower conductance (18 pS) channels were also detected. Bath application of phorbol dibutyrate (PDBu, 1 microM) increased the number and opening probability of the InsP3-induced channels.
Higashida
H
H
Laboratory of Biochemical Genetics, National Heart, Lung and Blood Institute, Bethesda, MD 20892.
Brown
D A
DA
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D004553:Electric Conductivity; D005910:Glioma / Q000503:physiopathology*; D006822:Hybrid Cells; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D051379:Mice; D009447:Neuroblastoma / Q000503:physiopathology*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D051381:Rats; D013403:Sugar Phosphates / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007295:Inositol Phosphates; D015221:Potassium Channels; D013403:Sugar Phosphates; D015240:Phorbol 12,13-Dibutyrate; D015544:Inositol 1,4,5-Trisphosphate; D001920:Bradykinin; D002118:Calcium