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.

Ca2+ channel antagonist actions in bladder smooth muscle: comparative pharmacologic and [3H]nitrendipine binding studies

1985 ◽  
Vol 63 (5) ◽  
pp. 453-462 ◽  
Author(s):  
F. B. Yousif ◽  
G. T. Bolger ◽  
A. Ruzycky ◽  
D. J. Triggle
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscles ◽  
Affinity Binding ◽  
Induced Responses ◽  
Bladder Smooth Muscle ◽  
Binding Studies ◽  
Tonic Component ◽  
High Affinity Binding ◽  
High Affinity

The actions of a series of 15 Ca2+ channel antagonists including D-6(X), nifedipine, and diltiazem were examined against K+ depolarization and muscarinic receptor induced responses in guinea pig bladder smooth muscle. Responses of bladder are very dependent upon extracellular Ca2+ and sensitive to the Ca2+ channel antagonists, the tonic component more than the phasic component of response. Regardless of stimulant, K+ or methylfurmethide (MF), or component of response, the same rank order of antagonist activities is expressed, suggestive of a single structure–activity relationship and the existence of a single category of binding site which may, however, exist in several affinity states. High affinity binding of [3H]nitrendipine (KD = 1.1 × 10−10 M) occurs in bladder membranes, and similar high affinity binding was found in microsomal preparations from other smooth muscles including guinea pig and rat lung, rat vas deferens, uterus, and stomach. [3H]nitrendipine binding in the bladder was sensitive to displacement by other 1,4-dihydropyridines, paralleling their pharmacologic activities and showing excellent agreement with binding data previously obtained for guinea pig ileal smooth muscle. Comparison of pharmacologic data for inhibition of K+- and MF-induced responses by a common series of Ca2+ channel antagonists in bladder and ileum revealed excellent correlations. Neither pharmacologic nor binding studies suggest significant differences in Ca2+ channel antagonist properties in smooth muscle from bladder and intestine.

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.

scholarly journals Efeito do hexametônio sobre a contratilidade de músculo liso de cobaios provocada pelo extrato aquoso do fungo Ramaria Flavo Brunnescens

1986 ◽  
Vol 8 (8) ◽  
pp. 67
Author(s):  
Ana Maria Chagas ◽  
Zuleica Tabarelli ◽  
Ruben Boelter ◽  
Lisandre Kipper ◽  
Rejane Mello Flores ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Muscle Contraction ◽  
Aqueous Extract ◽  
Smooth Muscle Contraction ◽  
Southern Brazil ◽  
Guinea Pig Ileum ◽  
Strain Transducer ◽  
Fungus Extract ◽  
The Difference

Animals poisoning by ingestion of Ramaria flava brunnescens fungus found in Eucalipto groves is common in Southern Brazil. This poisoning does not have an effective antidote yet and it is common to avoid the toxicity by removing the animals from these fields or by using atropin when fungus intoxication signals appear. Present work was reallized to elucidate the manner and place of action of this fungus aqueous extract on isolated guinea pig ileum. For this purpose, we used Magnus Bath and strain transducer to Physiograph connect. Experiences were realized with 18 ileum tested with 10 mcg Nicotine. 24.600 mcg Ramaria flavo brunnescens fungus' aqueous extract and 30 mcg Hexametonium. Those concentrations were choosen from pilot experiences. The results showed that uses of this fungus extract provokes smooth muscle contraction similar to that of nicotin, the difference between both occurs due to Hexametone blockade impossibility. This fact suggests that the death mechanism of animals that eat this fungus is not due to ganglionar stimulation.

K transport and mechanical responses of isolated longitudinal smooth muscle from guinea pig ileum

1961 ◽  
Vol 200 (4) ◽  
pp. 789-793 ◽  
Author(s):  
George B. Weiss ◽  
Robert E. Coalson ◽  
Leon Hurwitz
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Contractile Response ◽  
Muscle Tone ◽  
Muscle Layer ◽  
Smooth Muscle Contraction ◽  
Potassium Ion ◽  
Guinea Pig Ileum ◽  
Potassium Efflux ◽  
Longitudinal Smooth Muscle

The longitudinal smooth muscle layer of the guinea pig ileum was isolated in order to investigate its contractile responses and unidirectional K42 fluxes. Pilocarpine (7.5 x 10–6 m), acetylcholine (6.6 x 10–6 m), and a modified Tyrode's solution in which potassium ion was substituted for almost all the sodium ion were employed as excitatory agents. Cocaine (8.5 x 10–4 m) and a calcium-free Tyrode's solution served as inhibitory agents. Smooth muscle tone and potassium efflux of this relatively pure tissue were both increased by all three excitatory substances. Moreover, acetylcholine and pilocarpine produced a decrease in the influx of potassium ion. Bathing the tissue in a calcium-free medium for 1 hour before introducing pilocarpine to the muscle bath eliminated the contractile response that this drug ordinarily produces, but did not diminish appreciably the increase in K42 efflux. These observations are qualitatively similar to results previously obtained in analogous experiments on isolated whole ileum. In addition, cocaine (8.5 x 10–4 m) was found to block the contractile response and about three-quarters of the enhanced K42 efflux elicited by the isotonic potassium solution. It is presumed that cocaine acting at the membrane impedes ion fluxes important for smooth muscle contraction.

Muscarinic receptors on nerves and muscles in opossum esophagus muscularis mucosa

1987 ◽  
Vol 65 (9) ◽  
pp. 1903-1907 ◽  
Author(s):  
E. E. Daniel ◽  
J. Jury ◽  
P. Bowker
Keyword(s):  
Smooth Muscle ◽  
Substance P ◽  
Guinea Pig ◽  
Muscarinic Receptors ◽  
Smooth Muscles ◽  
Muscle Contractions ◽  
Muscularis Mucosa ◽  
Field Stimulation ◽  
Guinea Pig Ileum ◽  
Smooth Muscle Contractions

The muscarinic receptors of muscularis mucosa have some recognition properties that suggest they resemble receptors of the M1 sybtype. The nerves of these tissues also contain muscarinic receptors which inhibit tonic contractions caused by release of a substance-P-like material by field stimulation. These receptors also appear to be M1 in type as they are maximally activated by McNeil A343 as well as by carbachol (pD2, 5.5 and 7.5, respectively). They are also inhibited by pirenzepine, as well as by atropine (negative logarithms of the required dose for 50% inhibition or potentiation, 6.6–6.7 compared with 8.2–8.3). Hexahydrosiladifenidol, an antagonist selective for M2 receptors of guinea pig ileum, had a low (~7.1) pA2 value for antagonism of both agonists in smooth muscle in this tissue. However, it was closer to atropine in potency with respect to potentiating tonic responses to field stimulation or to inhibiting phasic responses to field stimulation than it was to antagonizing smooth muscle contractions. Thus, atropine was about 40 times more potent than pirenzepine and 2–5 times more potent than hexahydrosilafenidol. There were some quantitative differences in the effectiveness of these three antagonists in blocking the phasic (acetylcholine-mediated) response to field stimulation. Atropine was 70–100 times more potent than pirenzepine and 8–25 times more potent than hexahydrosiladifenidol. This greater potency difference for inhibition of phasic contractions compared with potentiation of tonic contractions was discussed. This tissue appears to be one of the first smooth muscles in which both nerves and muscles contain muscarinic receptors with some recognition properties resembling those of the M1 subtype.

Contraction of guinea pig ileal smooth muscle by acetyl glyceryl ether phosphorylcholine

1981 ◽  
Vol 241 (3) ◽  
pp. C130-C133 ◽  
Author(s):  
S. R. Findlay ◽  
L. M. Lichtenstein ◽  
D. J. Hanahan ◽  
R. N. Pinckard
Keyword(s):  
Biological Activity ◽  
Smooth Muscle ◽  
Guinea Pig ◽  
Muscle Contraction ◽  
Glyceryl Ether ◽  
Platelet Activating Factor ◽  
Smooth Muscle Contraction

Acetyl glyceryl ether phosphorylcholine (AGEPC) is a chemical that has the biological activity of what was formerly termed platelet-activating factor. We report here that synthetic AGEPC induces the contraction of guinea pig ileal smooth muscle. Antagonists of histamine, acetylcholine, and slow-reacting substances (SRS) do not block AGEPC-induced contraction. These responses were long lasting, resistant to washing, and displayed complete agonist specific desensitization. Histamine- and SRS-induced contractions were unaffected by AGEPC. These studies show that AGEPC has the potential to produce a component of anaphylactically induced smooth muscle contraction.

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