The effects of the Rho-kinase inhibitor, Y-27632 on Ca2+-sensitization of force induced by arachidonic acid (AA), phorbol 12,13-dibutyrate (PDBu), GTPγS, and by the stable thromboxane analog, 9,11-dideoxy-9α,11α-methanoepoxy-PGF(2α) (U-46619), were determined in α-toxin-permeabilized smooth muscles. Y-27632 relaxed (up to 99%) Ca2+-sensitization by GTPγS (10 μM) and U-46619 (1 μM), but not by PDBu (20 μM), and reduced GTPγS-induced myosin light chain (MLC20) phosphorylation from 28% to 17% (P=0.002). GTPγS-induced force sensitization was inhibited by Y-27632 more potently when the inhibitor was added during the plateau of force than prior to stimulation. In α-toxin-permeabilized smooth muscle, Y-27632 inhibited AA (50 μM)-induced Ca2+-sensitization of force (by 66±1.3%) and reduced MLC20 phosphorylation. In contrast, Y-27632 did not relax force Ca2+-sensitized by AA in smooth muscle permeabilized with Triton X-100. We conclude that (i) AA induces Ca2+-sensitization through dual mechanisms, one mediated by Rho-kinase (or a related kinase), and (ii) Rho-kinase is not required for phorbol ester-induced Ca2+-sensitization. Copyright (C) 1998 Federation of European Biochemical Societies.
|Number of pages||5|
|State||Published - Nov 27 1998|
Bibliographical noteFunding Information:
We thank Dr. S. Murakami, Ms. A. Yoshimura and Mr. Miura of Yoshitomi Pharmaceutical Industries, Ltd. for generous gifts of Y-27632. This work was supported by NIH Grant HL48807 and an American Heart Association National Scientist Development Grant (M.C.G.). We thank Susan Ramos for excellent technical assistance.
- Kinase C
- Signal transduction
ASJC Scopus subject areas
- Structural Biology
- Molecular Biology
- Cell Biology