Y27632, a Rho-activated kinase inhibitor, normalizes dysregulation in alpha1-adrenergic receptor-induced contraction of Lyon hypertensive rat artery smooth muscle

Authors

  • Maria Regina Freitas,

    1. Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Université Louis Pasteur de Strasbourg, Faculté de Pharmacie, 67401, Illkirch-Cedex, France
    2. Departamento de Fisologia e Patologia, Laboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, João Pessoa, Brazil
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  • Masumi Eto,

    Corresponding author
    1. Department of Molecular Physiology and Biophysics, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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  • Jason A. Kirkbride,

    1. Department of Molecular Physiology and Biophysics, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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  • Christa Schott,

    1. Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Université Louis Pasteur de Strasbourg, Faculté de Pharmacie, 67401, Illkirch-Cedex, France
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  • Jean Sassard,

    1. Département de Physiologie et Pharmacologie Clinique, Université de Lyon1, Lyon, France
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  • Jean-Claude Stoclet

    Corresponding author
    1. Pharmacologie et Physico-chimie des Interactions Cellulaires et Moléculaires, UMR CNRS 7034, Université Louis Pasteur de Strasbourg, Faculté de Pharmacie, 67401, Illkirch-Cedex, France
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Correspondence and reprints: masumi.eto@jefferson.edu

Abstract

RhoA-activated kinase (ROK) is involved in the disorders of smooth muscle contraction found in hypertension model animals and patients. We examined whether the α1-adrenergic receptor agonist-induced ROK signal is perturbed in resistance small mesentery artery (SMA) of Lyon genetically hypertensive (LH) rats, using a ROK antagonist, Y27632. Smooth muscle strips of SMA and aorta were isolated from LH and Lyon normotensive (LN) rats. After Ca2+-depletion and pre-treatment with phenylephrine (PE), smooth muscle contraction was induced by serial additions of CaCl2. In LH SMA Ca2+ permeated cells to a lesser extent as compared with LN SMA, while CaCl2-induced contraction of LH SMA was greater than that of LN SMA, indicating a higher ratio of force to Ca2+ in LH SMA contraction (Ca2+ sensitization). No hyper-contraction was observed in LH aorta tissues. Treatment of LH SMA with Y27632 restored both Ca2+ permeability and Ca2+-force relationship to levels seen for LN SMA. In response to PE stimulation, phosphorylation of CPI-17, a phosphorylation-dependent myosin phosphatase inhibitor protein, and MYPT1 at Thr853, the inhibitory phosphorylation site of the myosin phosphatase regulatory subunit, was increased in LN SMA, but remained unchanged in LH SMA. These results suggest that the disorder in ROK-dependent Ca2+ permeability and Ca2+-force relationship is responsible for LH SMA hyper-contraction. Unlike other hypertensive models, the ROK-induced hyper-contractility of LH SMA is independent of MYPT1 and CPI-17 phosphorylation, which suggests that ROK-mediated inhibition of myosin phosphatase does not affect SMA hyper-contractility in LH SMA cells.

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