title: The inhibitory effect of local anesthetics on bradykinin-induced phospholipase D activation in rat pheochromocytoma PC12 cells.
abstract: Bradykinin induces activation of phospholipase D (PLD) via B(2) receptors in neuronal cells. To demonstrate molecular mechanism(s) of local anesthetics, we examined whether and how local anesthetics affect bradykinin-induced PLD activation in PC12 cells. Using [(3)H]Palmitic acid-labeled PC12 cells stimulated with bradykinin, formation of [(3)H]phosphatidylbutanol was measured as a variable of PLD activity. Bradykinin-stimulated PLD activity seemed to peak at 2 min. Procaine, lidocaine, ropivacaine, bupivacaine, and tetracaine suppressed the bradykinin-induced PLD activation. We chose tetracaine, the most potent drug among the local anesthetics tested, to examine how local anesthetics affect phospholipase C, protein tyrosine kinase, and extracellular signal-regulated kinase, which are the molecules upstream of PLD. Tetracaine at clinically relevant concentrations (1 approximately 10 x 10(-4) M) inhibited the bradykinin-induced PLD activation in a dose- and time-dependent manner, but neither tetrodotoxin nor nifedipine affected the PLD activation. Tetracaine (5 x 10(-4) M) slightly potentiated brady-kinin-induced phospholipase C activation. Bradykinin-stimulated protein tyrosine-phosphorylation and extracellular signal-regulated kinase activation were not affected by tetracaine. Tetracaine significantly decreased PLD activity of membrane fraction in PC12 cells. These results indicate that local anesthetics depress bradykinin-induced lipid signaling pathway(s) and may provide some clues to understanding the molecular mechanisms of these drugs for anesthesia or analgesia.
  
  
  CONCLUSIONS
  Local anesthetics depressed the bradykinin-induced activation of phospholipase D (PLD) in PC12 cells. The effects of tetracaine, the most potent among the anesthetics tested, on the bradykinin-induced intracellular signaling molecules were examined. The bradykinin-induced PLD activation could be one of the potential intracellular signaling molecular sites of local anesthetic action.
authors.affiliation: Department of Anesthesiology, Gifu University School of Medicine, Tsukusamachi-40, Gifu City, Gifu 400-8705, Japan.
authors.forename: Jinen
authors.initials: J
authors.lastname: Chen
authors.forename: Shuji
authors.initials: S
authors.lastname: Dohi
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Tan
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Banno
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nozawa
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D001920:Bradykinin / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology; D007294:Inositol / Q000494:pharmacology; D008055:Lipids / Q000502:physiology; D009543:Nifedipine / Q000494:pharmacology; D016716:PC12 Cells; D010739:Phospholipase D / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013748:Tetracaine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000779:Anesthetics, Local; D008055:Lipids; D014665:Vasodilator Agents; D013748:Tetracaine; D013779:Tetrodotoxin; D007294:Inositol; D019833:Genistein; D017027:Protein Tyrosine Phosphatases; D010739:Phospholipase D; D009543:Nifedipine; D001920:Bradykinin