Receptor-dependent G protein-mediated Ca2+ sensitization in canine airway smooth muscle

Cell Calcium. 1997 Jul;22(1):21-30. doi: 10.1016/s0143-4160(97)90086-5.

Abstract

To determine the mechanisms of receptor-dependent Ca2+ sensitization in airway smooth muscle, canine tracheal smooth muscle (CTSM) was permeabilized with alpha-toxin or beta-escin. Although the effects of 5-hydroxytryptamine (100 microM), histamine (100 microM), and the thromboxane A2 analogue U-46619 (100 microM) were negligible, carbachol (100 microM) and endothelin-1 (ET-1, 1 microM) evoked additional contractions of 47.0 +/- 5.90% and 25.0 +/- 5.37% (n = 6) at pCa 6.7 with GTP (3 microM) (normalized to the maximum contraction at pCa 4.5) in alpha-toxin-permeabilized CTSM. GDP-beta-S (1 mM) reversed the carbachol and ET-1 responses completely. GTP-gamma-S (30 microM) and 4 beta-phorbol 12,13-dibutyrate (PDBu, 3 microM) increased the Ca2+ sensitivity (median effective pCa) of contraction by 1.8- and 4.4-fold, respectively (n = 4-11, P < 0.05). The effects of saturating concentrations of GTP-gamma-S and PDBu were additive. A synthetic peptide (T2) corresponding to the actin-binding site of calponin caused a dose-dependent contraction of beta-escin permeabilized CTSM, with the peak effect (25 +/- 4%, n = 4) at 1200 microM, PDBu (3 microM) caused contraction of the T2 peptide-treated CTSM. In conclusion, Ca2+ sensitization of CTSM depends on receptor type and is mediated by G proteins and protein kinase C whose effects are additive, with a partial contribution by calponin.

Publication types

  • Comparative Study

MeSH terms

  • 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
  • Aluminum / pharmacology
  • Animals
  • Bacterial Toxins / pharmacology
  • Calcium / metabolism*
  • Calcium-Binding Proteins / metabolism
  • Calponins
  • Carbachol / pharmacology
  • Cell Membrane Permeability / drug effects
  • Dogs
  • Endothelin-1 / pharmacology
  • Escin / pharmacology
  • Female
  • Fluorine / pharmacology
  • GTP-Binding Proteins / metabolism*
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology
  • Hemolysin Proteins / pharmacology
  • Histamine / pharmacology
  • Isometric Contraction
  • Male
  • Microfilament Proteins
  • Muscle, Smooth / drug effects
  • Muscle, Smooth / metabolism*
  • Peptide Fragments / chemical synthesis
  • Peptide Fragments / pharmacology
  • Phorbol 12,13-Dibutyrate / pharmacology
  • Prostaglandin Endoperoxides, Synthetic / pharmacology
  • Protein Kinase C / drug effects
  • Protein Kinase C / metabolism
  • Receptors, Muscarinic / drug effects
  • Receptors, Muscarinic / metabolism*
  • Serotonin / pharmacology
  • Thromboxane A2 / analogs & derivatives
  • Thromboxane A2 / pharmacology
  • Trachea / anatomy & histology
  • Trachea / metabolism*

Substances

  • Bacterial Toxins
  • Calcium-Binding Proteins
  • Endothelin-1
  • Hemolysin Proteins
  • Microfilament Proteins
  • Peptide Fragments
  • Prostaglandin Endoperoxides, Synthetic
  • Receptors, Muscarinic
  • staphylococcal alpha-toxin
  • fluoroaluminum
  • Fluorine
  • Serotonin
  • Phorbol 12,13-Dibutyrate
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Thromboxane A2
  • Escin
  • 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
  • Histamine
  • Carbachol
  • Aluminum
  • Protein Kinase C
  • GTP-Binding Proteins
  • Calcium