title: Involvement of Ca2+ sensitization in ropivacaine-induced contraction of rat aortic smooth muscle.
abstract: BACKGROUND
  The mechanisms of amino-amide local anesthetic agent-induced vasoconstriction remain unclear. The current study was designed to examine the roles of the protein kinase C (PKC), Rho kinase, and p44/42 mitogen-activated protein kinase (p44/42 MAPK) signaling pathways in calcium (Ca2+)-sensitization mechanisms in ropivacaine-induced vascular contraction.
  
  
  METHODS
  Endothelium-denuded rat aortic rings, segments, and strips were prepared. The cumulative dose-response relations of contraction and intracellular Ca2+ concentration to ropivacaine were tested, using isometric force transducers and a fluorometer, respectively. The dose-dependent ropivacaine-induced phosphorylation of PKC and p44/42 MAPK and the membrane translocation of Rho kinase were also detected using Western blotting.
  
  
  RESULTS
  Ropivacaine induced a dose-dependent biphasic contractile response and an increase in intracellular Ca2+ concentration of rat aortic rings, increasing at concentrations of 3 x 10 m to 3 x 10 m and decreasing from 10 m to 3 x 10 m, with a greater tension/intracellular Ca2+ concentration ratio than that induced with potassium chloride. The contraction was attenuated in a dose-dependent manner, by the PKC inhibitors bisindolylmaleimide I and calphostin C, the Rho-kinase inhibitor Y 27632, and the p44/42 MAPK inhibitor PD 098059. Ropivacaine also induced an increase in phosphorylation of PKC and p44/42 MAPK, and membrane translocation of Rho kinase in accordance with the contractile responses, which were also significantly inhibited by bisindolylmaleimide I and calphostin C, Y 27632, and PD 098059, correspondingly.
  
  
  CONCLUSIONS
  These findings demonstrated that PKC-, Rho kinase-, and p44/42 MAPK-mediated Ca2+-sensitization mechanisms are involved in the ropivacaine-induced biphasic contraction of rat aortic smooth muscle.
authors.affiliation: Department of Anesthesiology, Wakayama Medical University, Wakayama City, Japan.
authors.forename: Jingui
authors.initials: J
authors.lastname: Yu
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Tokinaga
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kuriyama
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Uematsu
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Mizumoto
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hatano
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D021381:Protein Transport; D051381:Rats; D017208:Rats, Wistar; D000077212:Ropivacaine; D014661:Vasoconstriction / Q000187:drug effects*; D054460:rho-Associated Kinases
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D047908:Intracellular Signaling Peptides and Proteins; D000077212:Ropivacaine; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002118:Calcium