Cooling-induced contraction of trachea isolated from normal and sensitized guinea-pigs

Cathepsin F Knockdown Induces Proliferation and Inhibits Apoptosis in Gastric Cancer Cells

Gastric cancer (GC) is one of the most common cancers in the world. The cathepsin F (CTSF) gene has recently been found to participate in the progression of several types of cancer. However, the clinical characteristics and function of CTSF in GC as well as its molecular mechanisms are not clear. Six GC cell lines and 44 paired adjacent noncancerous and GC tissue samples were used to assess CTSF expression by quantitative polymerase chain reaction (qPCR). We used lentivirus-mediated small hairpin RNA (Lenti-shRNA) against CTSF to knock down the expression of CTSF in GC cells. Western blot and qPCR were used to analyze the mRNA and related protein expression. The biological phenotypes of gastric cells were examined by cell proliferation and apoptosis assays. Microarray-based mRNA expression profile screening was also performed to evaluate the potential molecular pathways in which CTSF may be involved. The CTSF mRNA level was associated with tumor differentiation, depth of tumor invasion, and lymph node metastasis. Downregulation of CTSF expression efficiently inhibited apoptosis and promoted the proliferation of GC cells. Moreover, a total of 1,117 upregulated mRNAs and 1,143 downregulated mRNAs were identified as differentially expressed genes (DEGs). Further analysis identified the involvement of these mRNAs in cancer-related pathways and various other biological processes. Nine DEGs in cancer-related pathways and three downstream genes in the apoptosis pathway were validated by Western blot, which was mainly in agreement with the microarray data. To our knowledge, this is the first report investigating the effect of CTSF on the growth and apoptosis in GC cells and its clinical significance. The CTSF gene may function as a tumor suppressor in GC and may be a potential therapeutic target in the treatment of GC.

Temperature can influence gastric accommodation and sensitivity in functional dyspepsia with epigastric pain syndrome

BACKGROUND

Functional dyspepsia-epigastric pain syndrome (FD-EPS) is characterized pathophysiologically by visceral hypersensitivity, but the effect of the temperature stimulation on gastric function has been seldom studied.

AIM

The purpose of this study was to investigate the effects of liquid nutrients at different temperatures on the gastric accommodation, sensitivity, and gastric-wall compliance of healthy subjects (HS) and FD-EPS patients.

METHODS

Ten FD-EPS patients (Roma III criteria) and ten HS were recruited into the study. Intragastric pressure (IGP) and gastric perfusion were measured and compared following the administration of liquid nutrients at 37 °C on day 1 and at 8 °C on day 2.

RESULTS

Seven patients developed abdominal discomfort or abdominal pain after being given cold liquid nutrient. The administration of liquid nutrient at 8 °C resulted in an increase of IGP in HS (P=0.044), a significant decrease in gastric perfusion (P<0.0001), a marked increase in IGP (P=0.015), and a dramatic reduction in gastric wall compliance (P=0.012) in patients compared to the effects of liquid nutrient at 37 °C. In addition, IGP in patients was lower than that in HS at 37 °C liquid nutrient (P=0.036), and the gastric perfusion volume in patients at maximal satiety was also significantly reduced at 8 °C liquid nutrient compared with HS (P=0.017).

CONCLUSIONS

Cold stimulation can increase the IGP in HS and FD-EPS patients, elevate the visceral sensitivity and reduce the gastric volume of FD-EPS patients. FD-EPS patients who are sensitive to cold may develop epigastric discomfort or pain.

Expression and physiological roles of TRP channels in smooth muscle cells

Smooth muscles are widely distributed in mammal body through various systems such as circulatory, respiratory, gastro-intestinal and urogenital systems. The smooth muscle cell (SMC) is not only a contractile cell but is able to perform other important functions such as migration, proliferation, production of cytokines, chemokines, extracellular matrix proteins, growth factors and cell surface adhesion molecules. Thus, SMC appears today as a fascinating cell with remarkable plasticity that contributes to its roles in physiology and disease. Most of the SMC functions are dependent on a key event: the increase in intracellular calcium concentration ([Ca(2+)](i)). Calcium entry from the extracellular space is a major step in the elevation of [Ca(2+)](i) in SMC and involves a variety of plasmalemmal calcium channels, among them is the superfamily of transient receptor potential (TRP) proteins. TRPC (canonical), TRPM (melastatin), TRPV (vanilloid) and TRPP (polycystin), are widely expressed in both visceral (airways, gastrointestinal tract, uterus) and vascular (systemic and pulmonary circulation) smooth muscles. Mainly, TRPC, TRPV and TRPM are implicated in a variety of physiological and pathophysiological processes such as: SMC contraction, relaxation, growth, migration and proliferation; control of blood pressure, arterial myogenic tone, pulmonary hypertension, intestinal motility, gastric acidity, uterine activity during parturition and labor. Thus it is becoming evident that TRP are major element of SMC calcium homeostasis and, thus, appear as novel drug targets for a better management of diseases originating from SMC dysfunction.

Cooling-induced contraction of the rat gastric fundus: mediation via transient receptor potential (TRP) cation channel TRPM8 receptor and Rho-kinase activation

1. Cooling has been shown to induce contractions of several smooth muscles in vitro. However, the mechanism involved in the response is not yet known. In the present study, we investigated the possible involvement of transient receptor potential (TRP) cation channel TRPM8 receptors and the Rho-kinase pathway in cooling-induced contraction of the rat fundus. 2. Cooling-induced contractions were inversely proportional to temperature. Contractions were significantly reduced (by 65.6 +/- 2.4%; P < 0.05) in a Ca2+-free (1 mmol/L EGTA) medium, but were not significantly inhibited by nifedipine (10(-6) mol/L). 3. Capsazepine (3 x 10(-6) and 3 x 10(-5) mol/L), a TRPM8 receptor antagonist, inhibited cooling-induced contraction of the rat gastric fundus. 4. The Rho-kinase inhibitor Y-27632 concentration-dependently inhibited cooling-induced contraction of the gastric fundus, producing approximately 90% inhibition at a concentration of 10(-5) mol/L. Contractions were also inhibited by genistein (3 x 10(-5) mol/L), a tyrosine kinase inhibitor, but not by GF 109203X (10(-7) mol/L), a protein kinase C inhibitor. 5. Using reverse transcription-polymerase chain reaction techniques, it was observed that the mRNA for the TRPM8 receptor and Rho-kinase were expressed in the rat gastric fundus. 6. These results would suggest that cooling-induced contraction of the rat fundus is mediated by activation of TRPM8 receptors via a mechanism involving activation of Rho-kinase.

Effects of ouabain on human bronchial muscle in vitro

The effects of ouabain, an inhibitor of the plasmalemmal Na(+)/K(+)-ATPase activity, were examined in human isolated bronchus. Ouabain produced concentration-dependent contraction with -logEC(50)=7.16+/-0.11 and maximal effect of 67+/-4% of the response to acetylcholine (1 mM). Ouabain (10 microM)-induced contraction was epithelium-independent and was not depressed by inhibitors of cyclooxygenase and lipoxygenase, antagonists of muscarinic, histamine H(1)-receptors and alpha-adrenoceptors, or neuronal Na(+) channel blockade. The inhibition of ouabain contraction in tissues bathed in K(+)-free medium, and the inhibition by ouabain of the K(+)-induced relaxation confirm that the contractile action of ouabain is mediated by inhibition of Na(+)/K(+)-ATPase. Furthermore, depolarization (16.4+/-0.9 mV) was observed in human isolated bronchus by intracellular microelectrode recording. Ouabain (10 microM)-induced contractions were abolished by a Ca(2+)-free solution but not by blockers of L-type Ca(2+) channels. In human cultured bronchial smooth muscle cells, ouabain (10 microM) produced a sustained increase in [Ca(2+)](i) (116+/-26 nM) abolished in Ca(2+)-free medium. Incubation with a Na(+)-free medium or amiloride (0.1 mM) markedly inhibited the spasmogenic effect of ouabain thus suggesting the role of Na(+)/Ca(2+) exchange in ouabain contraction while selective inhibitors of Na(+)/H(+)-antiport, Na(+)/K(+)/Cl(-)-antiport, or protein kinase C had no effect. Ouabain (10 microM) failed to increase inositol phosphate accumulation in human bronchus. Ouabain (10 microM) did not alter bronchial responsiveness to acetylcholine or histamine but inhibited the relaxant effects of isoprenaline, forskolin, levcromakalim, or sodium nitroprusside. These results indicate that ouabain acts directly to produce contraction of human airway smooth muscle that depends on extracellular Ca(2+) entry unrelated to L-type channels and involving the Na(+)/Ca(2+)-antiporter.

Effects of phorbol 12,13-diacetate on human isolated bronchus

Protein kinase C appears to be involved in the regulation of airway contractility. Phorbol 12,13-diacetate (PDA; 0.01-10 microM), a protein kinase C activator, produced a transient relaxation followed by a sustained contraction of human isolated bronchus. Different protein kinase C inhibitors (calphostin C, staurosporine and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine) (H-7), nifedipine (NIF; 1 microM) or incubation with Ca(2+)-free medium, inhibited the spasmogenic response to phorbol, while ouabain (10 microM) suppressed only the initial relaxation. These results indicate that the initial relaxation, in response to PDA, is related to the activation of Na(+)/K(+)-ATPase, while the ensuing contraction depends on extracellular Ca(2+) entry.Incubation with PDA (1-5 microM) depressed the maximal relaxation to theophylline and caffeine obtained at 37 degrees C but augmented the spasmogenic responses to methylxanthines (10 mM) obtained in cooled preparations. These effects do not result apparently from increased extracellular entry of Ca(2+), but instead, from facilitation of the release of Ca(2+) from intracellular stores.

Effect of serotonin and calcium in normal and sensitized guinea pig isolated trachea

Tracheal strips from normal and actively sensitized guinea pigs were studied to determine the responses to serotonin (5-hydroxytryptamine, 5-HT; 1 nM-0.1 mM) and ouabain (0.1 microM-0.1 mM), and the effects of increasing the extracellular calcium (Cao) concentration on tonic contractions elicited by 5-HT. Sensitized trachea exhibited an increased responsiveness and sensitivity to 5-HT and ouabain. Increases in Cao to achieve final concentrations of 5, 10 and 20 mM caused concentration-related relaxations of normal and sensitized tissues contracted to a similar plateau level with 5-HT. Inhibition of the Na+/K(+)-ATPase by ouabain (10 microM) reversed the effects of Cao from relaxation to contraction in normal and sensitized tissues contracted with 5HT. Sensitized preparations showed reduced relaxations in response to Cao (10-20 mM), and sensitized, ouabain-treated, trachea showed augmented contractions to Cao (10-20 mM) when compared to normal tissues. These results demonstrate a decreased membrane-stabilizing effect of Cao in sensitized trachea and the implication of the Na+/K(+)-ATPase in the regulation of membrane stability by Cao, suggesting a possible relevance to those mechanisms underlying airway hyperreactivity.

H-7, a protein kinase C inhibitor, inhibits spontaneous tone and spasmogenic responses in normal and sensitized guinea pig trachea

1. H-7, a protein kinase C inhibitor, fully inhibited the spontaneous and stimulated (KCl 20 mM or histamine 0.5 mM) tone of trachea from normal and sensitized guinea pig. 2. H-7 depressed the concentration-contraction curves to KCl, histamine or 5-hydroxytryptamine in epithelium-denuded, indomethacin-treated, trachea from normal and sensitized guinea pigs while responses to CaCl2 (in Ca2+ -free, K+ -depolarized tissues) and acetylcholine were not affected. 3. H-7 (100 microM did not depress Ca2+ (20 microM-induced contraction of Triton X-100 skinned trachea. 4. These results suggest the involvement of PKC in the maintenance of spontaneous tone and spasmogenic responses of guinea pig trachea.

Effect of guinea-pig purified immunoglobulin G1 on the responsiveness of tracheal, aortic, vas deferens and ileum smooth muscles

BACKGROUND

Smooth muscles hyperresponsiveness is a common feature in anaphylaxis and allergic diseases.

OBJECTIVE

The aim of the present work was to investigate the effect of in vitro passive sensitization with highly purified immunoglobulin G1 (IgG1) on the responsiveness of tracheal, aortic, vas deferens and ileum smooth muscles.

METHODS

Firstly, IgG1, obtained from actively sensitized BFA guinea-pigs, was purified by Protein A-Sepharose column and characterized by enzyme-linked immunosorbent assay (ELISA) and immunoelectrophoresis analysis. Concentration-response curves to spasmogens (acetylcholine for trachea and vas deferens, noradrenaline for aorta and histamine for ileum) were established before and after in vitro passive sensitization with IgG1.

RESULTS

Contractile responses and maximal contractions were significantly enhanced after passive sensitization for all the organs. Maximal contractions were significantly increased in the trachea (+46.7%), aorta (+51%), vas deferens (+114.2%) and ileum (+117.2%). At the end of the experiments, the application of the sensitizing antigen induced a significant Schultz-Dale reaction of the smooth muscles.

CONCLUSION

The present results show that the in vitro application of purified IgG1 can produce non-specific smooth muscle hyperreactivity and hypersensitivity. So, IgG1 can be considered as the main factor involved in the genesis of sensitization-induced hyperresponsiveness, and probably play a great role in hyperreactivity observed during allergic diseases and anaphylaxis.

Effects of phorbol 12,13-diacetate and its influence on spasmogenic responses in normal and sensitized guinea-pig trachea

We have studied the effects of phorbol 12,13-diacetate (PDA) and its influence on a variety of spasmogenic responses in trachea isolated from normal and sensitized guinea-pigs. Tracheal preparations were denuded of epithelium, treated with indomethacin (2.8 microM), and cooled to 20 degrees C. In these experimental conditions, tracheal strips contracted to PDA (0.1 nM-1 microM). Contractions to PDA (1 microM) were greater in sensitized tissues. In normal trachea, contractions to PDA (0.1 microM) were depressed by H-7, 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine, (50 microM), amiloride (10 microM), verapamil (10 microM) and Ca(2+)-free exposure. Similar effects were obtained in sensitized trachea except that PDA-induced contraction was resistant to verapamil and Ca(2+)-free exposure. Cooling (20 degrees C) of normal trachea substantially depressed the response to CaCl2 (in K(+)-depolarized tissues), KCl, histamine and 5-hydroxytryptamine without affecting the spasm induced by acetylcholine. This inhibitory effect of cooling was not observed in sensitized trachea. PDA (0.1 microM) did not affect spasmogenic responses at 37 degrees C but counteracted the inhibitory effect of cooling in normal trachea. PDA had no effect on sensitized tissues. PDA (0.1-1 microM) did not alter Ca(2+)-induced contraction of skinned normal and sensitized trachea. These results support the hypothesis that intracellularly stored Ca2+ plays an important role in the activation of sensitized tracheal muscle.

Effect of temperature reduction on the vas deferens hyperresponsiveness of sensitized mice

1. The present study was designed to investigate the effect of active sensitization on the responsiveness of mouse vas deferens before and after moderate cooling. Contractile responses to noradrenaline (NA) were isometrically recorded in the vas deferens of control and ovalbumen-sensitized mice at 37 degrees C and 22 degrees C. 2. Enhancement of the vas deferens reactivity to NA was observed in the sensitized vs control mice at 37 degrees C and 22 degrees C (P < 0.01). In sensitized mice, maximal contraction was significantly increased compared with controls, and sensitization-induced hyperresponsiveness was greater at 22 degrees C compared with 37 degrees C. At 37 degrees C, contractile responses to barium chloride were significantly enhanced in the sensitized mice compared with controls, whereas the reduction of the temperature to 22 degrees C produced a marked inhibition of vas deferens contractions in both groups. Caffeine-induced contractions of the vas deferens were similar in control and sensitized mice at 37 degrees C. After moderate cooling to 22 degrees C, vas deferens from sensitized mice became hyperresponsive compared with controls. 3. Ouabain (0.1 mM) produced an increase of NA-induced contraction in control and sensitized vas deferens at 37 degrees C (P < 0.01). It had no significant effect in the control at 22 degrees C but produced a marked inhibition of NA-induced contraction in the sensitized vas deferens at 22 degrees C. Contractions to NA in the presence of vanadate (1 mM) were depressed in control and sensitized mice at both temperatures. 4. These results suggest that sensitization-induced hyperresponsiveness of the mouse vas deferens is mediated by an increased mobilization of intracellular calcium. The involvement of an unknown ouabain-sensitive pathway in sensitization-induced alterations is also discussed.

The effect of EDTA on contractile responses of guinea-pig trachea in calcium-free medium and on the recovery of the contractile responses in calcium-containing solution

1. Acetylcholine (0.1 mmol/l) and KCl (80 mmol/l) induce contractile responses in guinea-pig trachea. 2. In the absence of extracellular Ca, contractile responses to ACh or KCl decrease as the preincubation time or the EDTA concentration increases. 3. Exposure of the tissue to Ca-free medium decreases the basal tone. 4. Prolonged incubation in the presence of EDTA (1 mmol/l) promotes a delay in the recovery of the tonic component of the contraction elicited subsequently by acetylcholine and KCl in physiological salt solution, and abolishes the phasic one.

Effects of alkylxanthines on contractility of diaphragm fibres isolated from normal and sensitized guinea-pigs

This study investigates the effects of alkylxanthines on twitch tension generated by electrical stimulation (supramaximal pulses, 0.2 ms duration, 1 Hz) of diaphragm muscle fibres isolated from normal and actively-sensitized guinea-pigs. Caffeine, theophylline and theobromine increased, in a concentration-dependent manner (50-500 microM), twitch tension in normal and sensitized diaphragm. Caffeine (500 microM) enhanced contractility to a greater extent than theophylline or theobromine. Twitch potentiation by caffeine (500 microM) was significantly greater in sensitized diaphragm. Verapamil (0.1-100 microM) did not alter twitch contractions in the absence or presence of alkylxanthines in normal or sensitized strips. Dantrolene (0.01-100 microM) depressed, in a concentration-dependent fashion, twitch contractions of normal and sensitized diaphragm. The inhibitory concentration 50% (expressed as -log IC50) was 6.78 +/- 0.13 in normal tissues and 6.15 +/- 0.11 in sensitized tissues (n = 6 in each group; P < 0.05). Exposure to Ca(2+)-free, EGTA (0.1 mM)-containing medium, depressed twitch contraction of normal diaphragm to a lesser extent than that of sensitized diaphragm. Methylxanthines reversed depression of twitch contractions produced by exposure to dantrolene (5 microM) or a Ca(2+)-free medium. Adenosine (1-1000 microM) was without effect whereas enprofylline (50-500 microM) enhanced diaphragm contractility in normal tissues. This indicates that blockade of adenosine receptors is not involved in the inotropic effect of alkylxanthines in guinea-pig diaphragm. Results from this study suggest that alkylxanthines enhance diaphragm contractility in the guinea-pig by releasing intracellular Ca2+ and promoting extracellular Ca2+ entry through verapamil-insensitive pathways. An alteration of Ca2+ movements and stores may be present in the sensitized diaphragm.

Effects of cromakalim (BRL 34915) in trachea isolated from actively sensitized guinea-pigs

The effects of cromakalim were examined in tracheal strips isolated from normal (unsensitized) guinea-pigs and from animals actively sensitized to bovine serum albumin. Sensitized tracheae exhibited hyper-responsiveness to KCl, acetylcholine and histamine. In normal and sensitized tracheae, cromakalim (0.01-10 microM) produced a concentration-related suppression of spontaneous tone. The ability of cromakalim to relax tracheal strips was reduced when tone was raised by KCl (25 mM), acetylcholine (0.1 mM) or histamine (0.1 mM) and lost against KCl (120 mM)-induced spasm. Procaine (5 mM) abolished the relaxant effect of cromakalim whilst tetraethylammonium (8 mM) was without effect. These effects were similar in normal and sensitized tissues. Cromakalim (10 microM) produced minor alterations of the concentration-effect curves of KCl (1-100 mM), acetylcholine (1 nM-1 mM) and histamine (1 nM-1 mM) in normal and sensitized tissues. The results from this pharmacomechanical study do not support the hypothesis that altered properties of cromakalim-sensitive K+ channels underlie the airway hyper-reactivity induced by active sensitization to bovine serum albumin.

Effects of vanadate on responses of guinea-pig isolated trachea to spasmogens

The effects of vanadate on the contractility of the guinea-pig isolated trachea was examined. Vanadate (0.1 mM) produced a sustained contraction that was abolished in Ca(2+)-free EGTA (0.1 mM)-containing physiological salt solution but was resistant to verapamil (1 microM). Vanadate (0.1 mM) depressed tracheal responses to CaCl2 (in Ca(2+)-free depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine. For vanadate (10 microM), the inhibition of spasmogenic responses only reached statistical significance for histamine and 5-hydroxytryptamine. Caffeine (1 mM)-induced spasm (trachea at 20 degrees C in the presence of indomethacin (2.8 microM)) was not affected by vanadate (10 microM-0.1 mM). Vanadate (0.1 mM) slightly depressed the responses to KCl (50 mM), acetylcholine (1 mM), histamine (1 mM) or 5-hydroxytryptamine (0.1 mM) observed in Ca(2+)-free EGTA (0.1 mM)-containing physiological salt solution. Vanadate (0.5 mM) depressed Ca2+ (20 microM)-induced contraction of trachea which had been chemically skinned of its plasmalemmal membranes. The mechanism of the inhibitory effect of vanadate on tracheal responses to a variety of spasmogens remains obscure, but, under in-vitro conditions, vanadate clearly does not induce hyper-reactivity of airway smooth muscle to spasmogens.

Effects of Na+ transport inhibitors on guinea-pig tracheal responses to spasmogens

The effects of ouabain, amiloride, K(+)-free solution and low Na+ (25 mM) solution on the responses to CaCl2 (in Ca(2+)-free, K(+)-depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine were studied in guinea-pig isolated trachea. Ouabain (10 microM) did not alter the contractile responses to CaCl2, KCl and acetylcholine but depressed those to histamine and 5-hydroxytryptamine produced in normal Ca2+ (2.5 mM) and Ca(2+)-free (EGTA 0.1 mM) media. Amiloride (0.1 mM), K(+)-free solution, and low Na+ solution depressed responses to acetylcholine, histamine and 5-hydroxytryptamine produced in normal Ca2+ and Ca(2+)-free media. Ouabain and amiloride had no effect on responses of skinned strips to Ca2+. The mechanism of the inhibitory effects of these interventions is uncertain but the findings suggest that the availability of Na+ influences the airway smooth muscle responses to spasmogens.