Activation of Rho signaling contributes to lysophosphatidic acid-induced contraction of intact ileal smooth muscle of guinea-pig

2000 ◽  
Vol 78 (9) ◽  
pp. 729-736 ◽  
Author(s):  
Mayumi Mori ◽  
Hiromi Tsushima
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Lysophosphatidic Acid ◽  
Membrane Fraction ◽  
Smooth Muscles ◽  
Rho Kinase ◽  
Specific Inhibitor ◽  
High K ◽  
Rho A

To elucidate the possible role of Rho A/Rho-kinase on lysophosphatidic acid (LPA)-induced contraction in intact guinea-pig ileal smooth muscle, we examined effects of pretreatment with a specific inhibitor of Rho-kinase (Y-27632) on the LPA-induced contraction and MLC20 phosphorylation. In addition, we investigated whether LPA actually elicits an activation of Rho A by studying subcellular distribution of Rho A in unstimulated and stimulated smooth muscles by LPA. LPA induced a less intense, but sustained, contraction compared with ACh, and was accompanied by significant increases in MLC20 phosphorylation. The effects of LPA on tension and MLC20 phosphorylation were inhibited by Y-27632. The ACh-induced contraction, but not increases in MLC20 phosphorylation, was partially inhibited by Y-27632. High K+-induced contraction was unaffected by the inhibitor. LPA stimulated translocation of Rho A from the cytosol to the membrane fraction of the muscle. Translocation of Rho A was also induced by ACh and high K+. These results suggest that LPA-induced contraction of intact ileal smooth muscle is dominated through activation of Rho A and Rho-kinase and subsequent increases in MLC20 phosphorylation.Key words: lysophosphatidic acid, Rho, Rho-kinase, ileal smooth muscle.

PKC δ-isoform translocation and enhancement of tonic contractions of gastrointestinal smooth muscle

2007 ◽  
Vol 292 (3) ◽  
pp. G887-G898 ◽  
Author(s):  
Daniel P. Poole ◽  
John B. Furness
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscles ◽  
Specific Inhibitor ◽  
Smooth Muscle Contraction ◽  
Enteric Neurons ◽  
Guinea Pig Ileum ◽  
Tonic Component ◽  
Gastrointestinal Smooth Muscle ◽  
Immunohistochemical Evidence

PKC is involved in mediating the tonic component of gastrointestinal smooth muscle contraction in response to stimulation by agonists for G protein-coupled receptors. Here, we present pharmacological and immunohistochemical evidence indicating that a member of the novel PKC isoforms, PKC-δ, is involved in maintaining muscarinic receptor-coupled tonic contractions of the guinea pig ileum. The tonic component of carbachol-evoked contractions was enhanced by an activator of conventional and novel PKCs, phorbol 12,13-dibutyrate (PDBu; 200 nM or 1 μM), and by an activator of novel PKCs, ingenol 3,20-dibenzoate (IDB; 100 or 500 nM). Enhancement was unaffected by concentrations of bisindolylmaleimide I (BIM-I; 22 nM) that block conventional PKCs or by a PKC-ε-specific inhibitor peptide but was attenuated by higher doses of BIM-I (2.2 μM). Relevant proteins were localized at a cellular and subcellular level using confocal analysis. Immunohistochemical staining of the ileum showed that PKC-δ was exclusively expressed in smooth muscles distributed throughout the layers of the gut wall. PKC-ε immunoreactivity was prominent in enteric neurons but was largely absent from smooth muscle of the muscularis externa. Treatment with PDBu, IDB, or carbachol resulted in a time- and concentration-dependent translocation of PKC-δ from the cytoplasm to filamentous structures within smooth muscle cells. These were parallel to, but distinct from, actin filaments. The translocation of PKC-δ in response to carbachol was significantly reduced by scopolamine or calphostin C. The present study indicates that the tonic carbachol-induced contraction of the guinea pig ileum is mediated through a novel PKC, probably PKC-δ.

Role of Rho-kinase in guinea-pig gallbladder smooth muscle contraction

2006 ◽  
Vol 534 (1-3) ◽  
pp. 210-217 ◽  
Author(s):  
Teresa Quinn ◽  
Ronan Feighery ◽  
Alan William Baird
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Muscle Contraction ◽  
Rho Kinase ◽  
Smooth Muscle Contraction

scholarly journals Prostaglandin D2 Induces Ca2+ Sensitization of Contraction without Affecting Cytosolic Ca2+ Level in Bronchial Smooth Muscle

2018 ◽  
Vol 19 (10) ◽  
pp. 3036 ◽  
Author(s):  
Wataru Suto ◽  
Yusuke Ando ◽  
Takahiro Hirabayashi ◽  
Fumiko Takenoya ◽  
Seiji Shioda ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Kinase Inhibitor ◽  
Active Form ◽  
Smooth Muscles ◽  
Rho Kinase ◽  
Allergic Airway Inflammation ◽  
Prostaglandin D2 ◽  
Smooth Muscle Contractility ◽  
High K ◽  
Rho Kinase Inhibitor

Prostaglandin D2 (PGD2) is one of the key lipid mediators of allergic airway inflammation, including bronchial asthma. However, the role of PGD2 in the pathogenesis of asthma is not fully understood. In the present study, the effect of PGD2 on smooth muscle contractility of the airways was determined to elucidate its role in the development of airway hyperresponsiveness (AHR). In isolated bronchial smooth muscles (BSMs) of naive mice, application of PGD2 (10−9–10−5 M) had no effect on the baseline tension. However, when the tissues were precontracted partially with 30 mM K+ (in the presence of 10−6 M atropine), PGD2 markedly augmented the contraction induced by the high K+ depolarization. The PGD2-induced augmentation of contraction was significantly inhibited both by 10−6 M laropiprant (a selective DP1 antagonist) and 10−7 M Y-27632 (a Rho-kinase inhibitor), indicating that a DP1 receptor-mediated activation of Rho-kinase is involved in the PGD2-induced BSM hyperresponsiveness. Indeed, the GTP-RhoA pull-down assay revealed an increase in active form of RhoA in the PGD2-treated mouse BSMs. On the other hand, in the high K+-depolarized cultured human BSM cells, PGD2 caused no further increase in cytosolic Ca2+ concentration. These findings suggest that PGD2 causes RhoA/Rho-kinase-mediated Ca2+ sensitization of BSM contraction to augment its contractility. Increased PGD2 level in the airways might be a cause of the AHR in asthma.

scholarly journals Mechanisms of regulation electric and contractile activity smooth muscle cells: the role of cytoskeleton

2008 ◽  
Vol 7 (4) ◽  
pp. 31-37
Author(s):  
M. A. Medvedev ◽  
M. B. Baskakov ◽  
S. V. Gusakova ◽  
I. V. Kovalyov ◽  
O. S. Melnik ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Muscle Cells ◽  
Mechanisms Of Action ◽  
Electric Stimulus ◽  
Cytochalasine B

The influence of modulation of cytoskeleton by colchicine, vinblastine, cytochalasine B and docetaxel on contractile reactions of smooth muscle cells caused by electric stimulus, depolarization, phenylephrine has been investigated by the mechanographical method, by the methods of the double sucrose gup junction. It is established, that induced by a isoosmotic hyperpotassium solution of reduction of smooth muscle of the rat’s aorta, and also caused depolarization stimulus potentials of action and reductions smooth muscle cells from guinea pig urethra, depend more on the condition of microfilaments cytoskeleton than on microtubules. The reduction of smooth muscles cells of an aorta of the rat, caused by isoosmotic striction, is suppressed under the destruction microfilaments whereas the reduction in a hyperosmotic solution depends on a condition of both microfilaments, and microtubules. Cytoskeleton’s microfilaments of aorta’s smooth muscles and microtubules of smooth muscles of cells ureter are involved in mechanisms of action phenylephrine’s action on contractile activity of smooth muscle cells of an aorta and ureter.

Role of extracellular calcium and calmodulin in prolactin secretion induced by hyposmolarity, thyrotropin-releasing hormone, and high K+ in GH4C1 cells

1990 ◽  
Vol 123 (2) ◽  
pp. 218-224 ◽  
Author(s):  
Xiangbing Wang ◽  
Noriyuki Sato ◽  
Monte A. Greer ◽  
Susan E. Greer ◽  
Staci McAdams
Keyword(s):  
Smooth Muscle ◽  
Muscle Relaxant ◽  
Prolactin Secretion ◽  
Thyrotropin Releasing Hormone ◽  
Dependent Manner ◽  
Cell Toxicity ◽  
High K ◽  
Dose Dependent ◽  
Smooth Muscle Relaxant

Abstract. The mechanism by which 30% medium hyposmolarity induces PRL secretion by GH4C1 cells was compared with that induced by 100 nmol/l TRH or 30 mmol/l K+. Removing medium Ca2+, blocking Ca2+ channels with 50 μmol/l verapamil, or inhibiting calmodulin activation with 20 μmol/l trifluoperazine, 10 μmol/l chlorpromazine or 10 μmol/l pimozide almost completely blocked hyposmolarity-induced secretion. The smooth muscle relaxant, W-7, which is believed relatively specific in inhibiting the Ca2+-calmodulin interaction, depressed hyposmolarity-induced PRL secretion in a dose-dependent manner (r = −0.991, p<0.01 ). The above drugs also blocked or decreased high K+-induced secretion, but had much less effect on TRH-induced secretion. Secretion induced by TRH, hyposmolarity, or high K+ was optimal at pH 7.3-7.65 and was significantly depressed at pH 6.0 or 8.0, indicating that release of hormone induced by all 3 stimuli is due to an active cell process requiring a physiologic extracellular pH and is not produced by nonspecific cell toxicity. The data suggest hyposmolarity and high K+ may share some similarities in their mechanism of stimulating secretion, which is different from that of TRH.

scholarly journals Aging-associated changes in microRNA expression profile of internal anal sphincter smooth muscle: Role of microRNA-133a

2016 ◽  
Vol 311 (5) ◽  
pp. G964-G973 ◽  
Author(s):  
Jagmohan Singh ◽  
Ettickan Boopathi ◽  
Sankar Addya ◽  
Benjamin Phillips ◽  
Isidore Rigoutsos ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Smooth Muscles ◽  
Smooth Muscle Contractility ◽  
Network Analyses ◽  
Rhoa Signaling

A comprehensive genomic and proteomic, computational, and physiological approach was employed to examine the (previously unexplored) role of microRNAs (miRNAs) as regulators of internal anal sphincter (IAS) smooth muscle contractile phenotype and basal tone. miRNA profiling, genome-wide expression, validation, and network analyses were employed to assess changes in mRNA and miRNA expression in IAS smooth muscles from young vs. aging rats. Multiple miRNAs, including rno-miR-1, rno-miR-340-5p, rno-miR-185, rno-miR-199a-3p, rno-miR-200c, rno-miR-200b, rno-miR-31, rno-miR-133a, and rno-miR-206, were found to be upregulated in aging IAS. qPCR confirmed the upregulated expression of these miRNAs and downregulation of multiple, predicted targets ( Eln, Col3a1, Col1a1, Zeb2, Myocd, Srf, Smad1, Smad2, Rhoa/Rock2, Fn1, Tagln v2, Klf4, and Acta2) involved in regulation of smooth muscle contractility. Subsequent studies demonstrated an aging-associated increase in the expression of miR-133a, corresponding decreases in RhoA, ROCK2, MYOCD, SRF, and SM22α protein expression, RhoA-signaling, and a decrease in basal and agonist [U-46619 (thromboxane A2analog)]-induced increase in the IAS tone. Moreover, in vitro transfection of miR-133a caused a dose-dependent increase of IAS tone in strips, which was reversed by anti-miR-133a. Last, in vivo perianal injection of anti-miR-133a reversed the loss of IAS tone associated with age. This work establishes the important regulatory effect of miRNA-133a on basal and agonist-stimulated IAS tone. Moreover, reversal of age-associated loss of tone via anti-miR delivery strongly implicates miR dysregulation as a causal factor in the aging-associated decrease in IAS tone and suggests that miR-133a is a feasible therapeutic target in aging-associated rectoanal incontinence.

Role of cGMP in relaxation of vascular and other smooth muscle

1989 ◽  
Vol 67 (4) ◽  
pp. 251-262 ◽  
Author(s):  
Kanji Nakatsu ◽  
Jack Diamond
Keyword(s):  
Smooth Muscle ◽  
Muscle Relaxation ◽  
Smooth Muscles ◽  
Phosphodiesterase Inhibitors ◽  
Current Evidence ◽  
Smooth Muscle Relaxation ◽  
Drug Induced ◽  
Intracellular Cgmp ◽  
Tissue Content

The hypothesis that the relaxant action of many drugs on vascular and other smooth muscle is mediated by increases in intracellular cGMP, the "cGMP hypothesis," is gaining wide acceptance. While much information supporting this idea can be found in the literature, there is also a significant amount of information indicating that an elevation in the tissue content of cGMP is by itself insufficient to cause smooth muscle relaxation. The literature is reviewed with reference to the criteria that need to be fulfilled to consider cGMP as the second messenger mediating relaxation of smooth muscle by a drug; i.e., activation of guanylate cyclase, elevation of tissue content of cGMP, potentiation by phosphodiesterase inhibitors, antagonism by inhibitors of cGMP synthesis, and production of relaxation by cGMP analogues. For each criterion, key observations supporting the hypothesis are considered, followed by examples of important observations not consistent with the hypothesis. It is concluded that in some smooth muscles, for example, rat myometrium and vas deferens, cGMP is not a mediator of drug-induced relaxation. In other smooth muscles, including vascular smooth muscle, cGMP appears to play an important role in the relaxation process; but current evidence suggests that other factors are also important and that the cGMP hypothesis may need to be modified.Key words: cGMP, vascular relaxation, smooth muscle relaxation, vasodilators.

scholarly journals Expression and functional role of Rho-kinase in rat urinary bladder smooth muscle

2003 ◽  
Vol 138 (5) ◽  
pp. 757-766 ◽  
Author(s):  
Alexandra Wibberley ◽  
Zunxuan Chen ◽  
Erding Hu ◽  
J Paul Hieble ◽  
Timothy D Westfall
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Functional Role ◽  
Rho Kinase ◽  
Bladder Smooth Muscle ◽  
Rat Urinary Bladder ◽  
Urinary Bladder Smooth Muscle

scholarly journals Role of SM22 in the differential regulation of phasic vs. tonic smooth muscle

2015 ◽  
Vol 308 (7) ◽  
pp. G605-G612 ◽  
Author(s):  
Satish Rattan ◽  
Mehboob Ali
Keyword(s):  
Smooth Muscle ◽  
Kinase Inhibitor ◽  
Smooth Muscles ◽  
Rho Kinase ◽  
Actin Binding ◽  
Control Mechanisms ◽  
Molecular Control ◽  
Tonic Smooth Muscle ◽  
Before And After ◽  
Protein Kinase C Inhibitor

Preliminary proteomics studies between tonic vs. phasic smooth muscles identified three distinct protein spots identified to be those of transgelin (SM22). The latter was found to be distinctly downregulated in the internal anal sphincter (IAS) vs. rectal smooth muscle (RSM) SMC. The major focus of the present studies was to examine the differential molecular control mechanisms by SM22 in the functionality of truly tonic smooth muscle of the IAS vs. the adjoining phasic smooth muscle of the RSM. We monitored SMC lengths before and after incubation with pFLAG-SM22 (for SM22 overexpression), and SM22 small-interfering RNA. pFLAG-SM22 caused concentration-dependent and significantly greater relaxation in the IAS vs. the RSM SMCs. Conversely, temporary silencing of SM22 caused contraction in both types of the SMCs. Further studies revealed a significant reverse relationship between the levels of SM22 phosphorylation and the amount of SM22-actin binding in the IAS and RSM SMC. Data showed higher phospho-SM22 levels and decreased SM22-actin binding in the IAS, and reverse to be the case in the RSM SMCs. Experiments determining the mechanism for SM22 phosphorylation in these smooth muscles revealed that Y-27632 (Rho kinase inhibitor) but not Gö-6850 (protein kinase C inhibitor) caused concentration-dependent decreased phosphorylation of SM22. We speculate that SM22 plays an important role in the regulation of basal tone via Rho kinase-induced phosphorylation of SM22.

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