Evidence for myosin light chain kinase mediating noradrenaline-evoked cation current in rabbit portal vein myocytes

J Physiol. 2000 May 1;524 Pt 3(Pt 3):853-63. doi: 10.1111/j.1469-7793.2000.00853.x.


The role of myosin light chain kinase (MLCK) in the activation of the noradrenaline-evoked non-selective cation current (Icat) was examined with the whole-cell recording technique in single rabbit portal vein smooth muscle cells. Intracellular dialysis with 5 microM MLCK(11-19)amide, a substrate-specific peptide inhibitor of MLCK, markedly reduced the amplitude and rate of activation of noradrenaline-evoked Icat. A similar result was obtained when the cells were dialysed with 10 microM AV25, which also inhibits MLCK by an action at the auto-inhibitory domain of MLCK. Inhibitors of binding of ATP to MLCK, wortmannin and synthetic naphthalenesulphonyl derivatives (ML-7 and ML-9), at micromolar concentrations, also reduced the amplitude of noradrenaline-evoked Icat. ML-7 and ML-9 (both at 5 microM) reduced the amplitude of Icat induced by both guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) and 1-oleoyl-2-acetyl-sn-glycerol (OAG). MLCK(11-19)amide, AV25 and ML-9 did not inhibit the noradrenaline-evoked Ca2+-activated potassium current at a holding potential of 0 mV. In addition, MLCK(11-19)amide and AV25 did not reduce the non-selective cation current induced by ATP in rabbit ear artery cells. Intracellular dialysis with 2 microM Ca2+ and 9 microM calmodulin activated Icat, which developed over a period of about 5 min. Intracellular dialysis with the non-hydrolysable analogue of ATP, 5'-adenylylimidodiphosphate (AMP-PNP), reduced the amplitude and rate of activation of noradrenaline-evoked Icat. The results indicate that MLCK mediates noradrenaline-activated Icat in rabbit portal vein smooth muscle cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Adenylyl Imidodiphosphate / pharmacology
  • Amino Acid Sequence
  • Androstadienes / pharmacology
  • Animals
  • Calcium / metabolism
  • Calmodulin / pharmacology
  • Cations / metabolism
  • Diglycerides / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Male
  • Molecular Sequence Data
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / enzymology
  • Myosin-Light-Chain Kinase / chemistry
  • Myosin-Light-Chain Kinase / metabolism*
  • Norepinephrine / pharmacology*
  • Peptide Fragments / pharmacology
  • Phosphorylation
  • Portal Vein / drug effects
  • Portal Vein / enzymology*
  • Potassium / metabolism
  • Potassium Channels / physiology
  • Rabbits
  • Vasoconstrictor Agents / pharmacology*
  • Wortmannin


  • Androstadienes
  • Calmodulin
  • Cations
  • Diglycerides
  • Enzyme Inhibitors
  • Peptide Fragments
  • Potassium Channels
  • Vasoconstrictor Agents
  • Adenylyl Imidodiphosphate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • 1-oleoyl-2-acetylglycerol
  • Adenosine Triphosphate
  • Myosin-Light-Chain Kinase
  • Potassium
  • Calcium
  • Norepinephrine
  • Wortmannin