title: Phorbol ester inhibits bradykinin-stimulated inositol trisphosphate formation and calcium mobilization in neuroblastoma x glioma hybrid NG108-15 cells.
abstract: In neuroblastoma x glioma hybrid NG108-15 cells, bradykinin (BK) receptor stimulation leads to phosphoinositide hydrolysis, formation of inositol phosphates and mobilization of intracellular calcium. Treatment of the cells with 12-O-tetradecanoyl phorbol 13-acetate (TPA) suppressed the spike phase of increases in intracellular calcium concentration. In radioligand binding studies, TPA treatment did not interfere with [3H]BK specific binding to intact cells or to cell membranes. The ability of guanyl-5'-yl-imidodiphosphate to promote the conversion of the high affinity sites of the BK receptors into a low affinity sites was unaffected by TPA. TPA treatment showed the dose-dependent, noncompetitive inhibition of BK-stimulated formation of inositol trisphosphate. In the membrane preparations from TPA-treated cells, guanosine 5'-(3-O-thio)triphosphate-stimulated inositol trisphosphate formation was inhibited by 50%. These data indicate that TPA exerts its inhibitory action on BK responses at the sites of guanine nucleotide-binding protein or phospholipase C or both.
mesh_terms: D001920:Bradykinin / Q000037:antagonists & inhibitors*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004075:Diglycerides / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D005910:Glioma; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism*; D009447:Neuroblastoma; D011493:Protein Kinase C / Q000378:metabolism; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013403:Sugar Phosphates / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D004075:Diglycerides; D007295:Inositol Phosphates; D018002:Receptors, Bradykinin; D017981:Receptors, Neurotransmitter; D013403:Sugar Phosphates; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D001920:Bradykinin; D002118:Calcium