Bradykinin-evoked acetylcholine release via inositol trisphosphate-dependent elevation in free calcium in neuroblastoma x glioma hybrid NG108-15 cells

• Published in: The Journal of biological chemistry Vol. 265; no. 6; pp. 3577 - 3584
• Main Authors: Ogura, A, Myojo, Y, Higashida, H
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25-02-1990; American Society for Biochemistry and Molecular Biology
• Subjects: Acetylcholine - metabolism; Animals; Barium - pharmacology; Bradykinin - pharmacology; Calcium - metabolism; Cell Line; Evoked Potentials - drug effects; Glioma; Hybrid Cells - drug effects; Hybrid Cells - metabolism; Inositol 1,4,5-Trisphosphate - pharmacology; Membrane Potentials - drug effects; Mice; Neuroblastoma; Phorbol 12,13-Dibutyrate - pharmacology; Rats; Synapses - drug effects; Synapses - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)39808-4

The mechanism underlying the bradykinin (BK)-induced increase of acetylcholine (ACh) release was studied in neuroblastoma x glioma hybrid NG108-15 cells and their synapses formed onto mouse muscle cells. External application of BK or iontophoretic injection of extrinsic inositol 1,4,5-trisphosphate (InsP3) into the cytoplasm of NG108-15 cells produced membrane hyperpolarization in the hybrid cells and an increase in the frequency of miniature end-plate potentials (MEPPs) in paired myotubes. Ba2+ blocked the hyperpolarization in response to BK, but facilitation of MEPPs was still observed. InsP3-dependent facilitation of MEPPs was also observed in cells where the InsP3 injections produced no detectable hyperpolarization or even depolarization. Real-time quantitative monitoring of intracellular free Ca2+ concentration [( Ca2+]i) with fura-2 in single NG108-15 cells showed that BK application or InsP3 injection induced an elevation of [Ca2+]i which coincided in time with membrane hyperpolarization recorded from the same cell. The [Ca2+]i rise produced by InsP3 injection started from the single site of injection and that produced by BK began from a deep compartment of the cytoplasm of the NG108-15 cells. The BK- and InsP3-evoked facilitation of MEPPs and the [Ca2+]i rise were relatively independent of extracellular Ca2+. These findings suggest that the BK-induced ACh release results not from membrane potential changes but from a transient InsP3-dependent elevation of [Ca2+]i.