Relaxation of contracted rabbit tracheal and human bronchial smooth muscle by Y-27632 through inhibition of Ca2+ sensitization

Am J Respir Cell Mol Biol. 1999 Jun;20(6):1190-200. doi: 10.1165/ajrcmb.20.6.3441.

Abstract

The mechanism of Ca2+ sensitization of contraction has not been elucidated in airway smooth muscle (SM). To determine the role of a small G protein, rhoA p21, and its target protein, rho-associated coiled coil-forming protein kinase (ROCK), in receptor-coupled Ca2+ sensitization of airway SM, we studied the effect of (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexane carboxamide dihydrochloride, monohydrate (Y-27632), a ROCK inhibitor, on isometric contractions in rabbit tracheal and human bronchial SM. Y-27632 completely reversed 1 microM carbachol (CCh)-induced contraction of intact trachea with a concentration producing half-maximum inhibition of effect (IC50) of 1.29 +/- 0.2 microM (n = 5). Although 4beta-phorbol 12,13-dibutyrate (1 microM)-induced Ca2+ sensitization was relatively resistant to Y-27632 in alpha-toxin-permeabilized trachea, CCh (100 microM) plus guanosine triphosphate (GTP) (3 microM)- and guanosine 5'-O-(3'-thiotriphosphate) (10 microM)-induced contractions were relaxed completely by Y-27632 with IC50 of 1.44 +/- 0.3 (n = 6) and 1.15 +/- 0.3 microM (n = 6). Endothelin-1 (1 microM) plus GTP (3 microM)- developed force was also reversed by Y-27632 with IC50 of 4. 10 +/- 1.1 microM (n = 6) in the alpha-toxin-permeabilized bronchus. Both the rabbit and human SM expressed rhoA p21, ROCK I, and its isoform ROCK II. Collectively, rho/ROCK-mediated Ca2+ sensitization plays a central role in the sustained phase of airway SM contraction, and selective inhibition of this pathway may become a new strategy to resolve airflow limitation in asthma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Methyl-3-isobutylxanthine / pharmacology
  • Amides / pharmacology*
  • Animals
  • Bronchi / metabolism*
  • Calcium / antagonists & inhibitors*
  • Carbachol / pharmacology
  • Cholinergic Agents / pharmacology
  • Detergents / pharmacology
  • Dose-Response Relationship, Drug
  • Endothelin-1 / pharmacology
  • GTP-Binding Proteins / metabolism
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Marine Toxins
  • Muscle Contraction
  • Muscle, Smooth / metabolism*
  • Myosin-Light-Chain Kinase / metabolism
  • Octoxynol / pharmacology
  • Oxazoles / pharmacology
  • Phosphodiesterase Inhibitors / pharmacology
  • Protein Serine-Threonine Kinases / metabolism
  • Pyridines / pharmacology*
  • Rabbits
  • Signal Transduction
  • Trachea / metabolism*
  • Type C Phospholipases / pharmacology
  • rho-Associated Kinases

Substances

  • Amides
  • Cholinergic Agents
  • Detergents
  • Endothelin-1
  • Intracellular Signaling Peptides and Proteins
  • Marine Toxins
  • Oxazoles
  • Phosphodiesterase Inhibitors
  • Pyridines
  • Y 27632
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • calyculin A
  • Carbachol
  • Octoxynol
  • Protein Serine-Threonine Kinases
  • rho-Associated Kinases
  • Myosin-Light-Chain Kinase
  • Type C Phospholipases
  • GTP-Binding Proteins
  • Calcium
  • 1-Methyl-3-isobutylxanthine