Role of Rho-kinase in maintaining airway smooth muscle contractile phenotype

Eur J Pharmacol. 2004 Jan 1;483(1):71-8. doi: 10.1016/j.ejphar.2003.10.027.

Abstract

This study aims to investigate the role of Rho-kinase in phenotype switching and proliferation of bovine tracheal smooth muscle. To induce different phenotypic states, bovine tracheal smooth muscle strips were cultured (8 days) in 10% foetal bovine serum (foetal bovine serum, less contractile phenotype) or insulin (1 microM, hypercontractile phenotype) and compared to strips cultured in serum-free medium. In contraction experiments, the Rho-kinase inhibitor (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexane carboxamide (Y-27632, 1 microM) decreased sensitivity to methacholine and KCl and lowered maximal responsiveness to KCl in all strips irrespective of the phenotype present. To investigate the effects of Rho-kinase bovine tracheal smooth muscle phenotypic regulation, strips were pretreated with Y-27632 (1 microM) for 8 days. This resulted in a decreased maximal contractility to both methacholine and KCl, quantitatively comparable to the decrease in contractility induced by platelet-derived growth factor (PDGF, 10 ng/ml). The combination of Y-27632 and PDGF responded additively. Y-27632 did not affect basal or PDGF-induced bovine tracheal smooth muscle cell proliferation, determined both as increases in [3H]thymidine incorporation and cell number. Inhibitors of the p42/p44 mitogen-activated protein kinase (MAPK) pathway, the p38 MAPK pathway and the phosphatidyl inositol (PI) 3-kinase pathway all inhibited PDGF-induced proliferation and phenotype changes. These results show that the functional contribution of Rho-kinase to bovine tracheal smooth muscle contraction is not dependent on phenotypic state. In addition, Rho-kinase is not involved in phenotypic modulation or proliferation induced by PDGF, whereas p42/p44 MAPK, p38 MAPK and PI 3-kinase are. Rho-kinase is, however, a major regulator involved in the basal maintenance of contractility in bovine tracheal smooth muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bronchodilator Agents / pharmacology
  • Cattle
  • Cell Division / drug effects
  • Cell Division / physiology
  • Cells, Cultured
  • DNA / biosynthesis
  • Enzyme Inhibitors / pharmacology
  • Intracellular Signaling Peptides and Proteins
  • Isometric Contraction
  • Methacholine Chloride / pharmacology
  • Muscle Contraction / physiology
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / physiology*
  • Organ Culture Techniques
  • Phenotype
  • Potassium Chloride / pharmacology
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / physiology*
  • Tetrazolium Salts
  • Thiazoles
  • Thymidine / metabolism
  • Trachea / drug effects
  • Trachea / physiology*
  • rho-Associated Kinases

Substances

  • Bronchodilator Agents
  • Enzyme Inhibitors
  • Intracellular Signaling Peptides and Proteins
  • Tetrazolium Salts
  • Thiazoles
  • Methacholine Chloride
  • Potassium Chloride
  • DNA
  • Protein-Serine-Threonine Kinases
  • rho-Associated Kinases
  • thiazolyl blue
  • Thymidine