Possible involvement of Rho kinase in Ca2+ sensitization and mobilization by MCh in tracheal smooth muscle.
We examined the effects of Rho kinase on contraction and intracellular Ca2+ concentration ([Ca2+](i)) in guinea pig trachealis by measuring isometric force and the fura 2 signal [340- to 380-nm fluorescence ratio (F340/F380)]. A Rho kinase inhibitor, Y-27632 (1-1,000 microM), inhibited methacholine (MCh)-induced contraction, with a reduction in F340/F380 in a concentration-dependent manner. The values of EC(50) for contraction and F340/F380 induced by 1 microM MCh with Y-27632 were 27.3 +/- 5.1 and 524.1 +/- 31.0 microM, respectively. With 0.1 microM MCh, the values for these parameters were decreased to 1.0 +/- 0.1 and 98.2 +/- 6.2 microM, respectively. Tension-F340/F380 curves for MCh indicated that Y-27632 caused an ~50% inhibition of MCh-induced contraction, without a reduction in F340/F380. These effects of Y-27632 were not inhibited by a protein kinase C inhibitor, GF-109203X. Our results indicate that inhibition of Rho kinase attenuates both Ca2+ sensitization and [Ca2+](i).
Ito
S
S
The Second Department of Internal Medicine, School of Medicine, Nagoya University, Tsurumai-cho, Showa-ku, Nagoya 466-8560, Japan.
Kume
H
H
Honjo
H
H
Katoh
H
H
Kodama
I
I
Yamaki
K
K
Hayashi
H
H
D000577:Amides / Q000494:pharmacology; D000818:Animals; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D016085:Bronchoconstrictor Agents / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007424:Intracellular Fluid / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D016210:Methacholine Chloride / Q000494:pharmacology*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D013050:Spectrometry, Fluorescence; D014132:Trachea; D054460:rho-Associated Kinases
D000577:Amides; D016085:Bronchoconstrictor Agents; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008301:Maleimides; D011725:Pyridines; D016210:Methacholine Chloride; C108830:Y 27632; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; C070515:bisindolylmaleimide I; D002118:Calcium; D016257:Fura-2