Relaxation of contracted rabbit tracheal and human bronchial smooth muscle by Y-27632 through inhibition of Ca2+ sensitization.
نویسندگان
چکیده
The mechanism of Ca2+ sensitization of contraction has not been elucidated in airway smooth muscle (SM). To determine the role of a small G protein, rhoA p21, and its target protein, rho-associated coiled coil-forming protein kinase (ROCK), in receptor-coupled Ca2+ sensitization of airway SM, we studied the effect of (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexane carboxamide dihydrochloride, monohydrate (Y-27632), a ROCK inhibitor, on isometric contractions in rabbit tracheal and human bronchial SM. Y-27632 completely reversed 1 microM carbachol (CCh)-induced contraction of intact trachea with a concentration producing half-maximum inhibition of effect (IC50) of 1.29 +/- 0.2 microM (n = 5). Although 4beta-phorbol 12,13-dibutyrate (1 microM)-induced Ca2+ sensitization was relatively resistant to Y-27632 in alpha-toxin-permeabilized trachea, CCh (100 microM) plus guanosine triphosphate (GTP) (3 microM)- and guanosine 5'-O-(3'-thiotriphosphate) (10 microM)-induced contractions were relaxed completely by Y-27632 with IC50 of 1.44 +/- 0.3 (n = 6) and 1.15 +/- 0.3 microM (n = 6). Endothelin-1 (1 microM) plus GTP (3 microM)- developed force was also reversed by Y-27632 with IC50 of 4. 10 +/- 1.1 microM (n = 6) in the alpha-toxin-permeabilized bronchus. Both the rabbit and human SM expressed rhoA p21, ROCK I, and its isoform ROCK II. Collectively, rho/ROCK-mediated Ca2+ sensitization plays a central role in the sustained phase of airway SM contraction, and selective inhibition of this pathway may become a new strategy to resolve airflow limitation in asthma.
منابع مشابه
The role of RhoA-mediated Ca2+ sensitization of bronchial smooth muscle contraction in airway hyperresponsiveness.
Smooth muscle contraction is mediated by Ca2+-dependent and Ca2+-independent pathways. The latter Ca2+-independent pathway, termed Ca2+ sensitization, is mainly regulated by a monomeric GTP binding protein RhoA and its downstream target Rho-kinase. Recent studies suggest a possible involvement of augmented RhoA/Rho-kinase signaling in the elevated smooth muscle contraction in several human dise...
متن کاملPossible 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...
متن کاملK+ depolarization induces RhoA kinase translocation to caveolae and Ca2+ sensitization of arterial muscle.
KCl causes smooth muscle contraction by elevating intracellular free Ca2+, whereas receptor stimulation activates an additional mechanism, termed Ca2+ sensitization, that can involve activation of RhoA-associated kinase (ROK) and PKC. However, recent studies support the hypothesis that KCl may also increase Ca2+ sensitivity. Our data showed that the PKC inhibitor GF-109203X did not, whereas the...
متن کاملKCl evokes contraction of airway smooth muscle via activation of RhoA and Rho-kinase.
Airway smooth muscle (ASM) cells express voltage-dependent Ca2+ channels, primarily of the L-subtype. These may play a role in excitation-contraction coupling of ASM, although other signaling pathways may also contribute: one of these includes Rho and its downstream effector molecule Rho-associated kinase (ROCK). Although voltage-dependent Ca2+ influx and Rho/ROCK signaling have traditionally b...
متن کاملContribution of potassium channels, beta2-adrenergic and histamine H1 receptors in the relaxant effect of baicalein on rat tracheal smooth muscle
Objective(s): Baicalein, a compound extracted from a variety of herbs, showed various pharmacological effects. This study evaluated the relaxant effects of baicalein and its underlying molecular mechanisms of action on rat’s isolated tracheal smooth muscle.Materials and Methods: Tracheal smooth muscle were contracted by 10 μM methacholin...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- American journal of respiratory cell and molecular biology
دوره 20 6 شماره
صفحات -
تاریخ انتشار 1999