Intestinal disorders often co-occur with inflammation and dysmotility. However, drugs which simultaneously improve intestinal inflammation and co-occurring dysmotility are rarely reported. Atractylodin, a widely used herbal medicine, is used to treat digestive disorders. The present study was designed to characterize the effects of atractylodin on amelioration of both jejunal inflammation and the co-occurring dysmotility in both constipation-prominent (CP) and diarrhea-prominent (DP) rats. The results indicated that atractylodin reduced proinflammatory cytokines TNF-α, IL-1β, and IL-6 in the plasma and inhibited the expression of inflammatory mediators iNOS and NF-kappa B in jejunal segments in both CP and DP rats. The results indicated that atractylodin exerted stimulatory effects and inhibitory effects on the contractility of jejunal segments isolated from CP and DP rats respectively, showing a contractile-state-dependent regulation. Atractylodin-induced contractile-state-dependent regulation was also observed by using rat jejunal segments in low and high contractile states respectively (5 pairs of low/high contractile states). Atractylodin up-regulated the decreased phosphorylation of 20 kDa myosin light chain, protein contents of myosin light chain kinase (MLCK), and MLCK mRNA expression in jejunal segments of CP rats and down-regulated those increased parameters in DP rats. Taken together, atractylodin alleviated rat jejunal inflammation and exerted contractile-state-dependent regulation on the contractility of jejunal segments isolated from CP and DP rats respectively, suggesting the potential clinical implication for ameliorating intestinal inflammation and co-occurring dysmotility.
Animals ; Constipation* ; Cytokines ; Diarrhea* ; Herbal Medicine ; Inflammation* ; Interleukin-6 ; Myosin Light Chains ; Myosin-Light-Chain Kinase ; NF-kappa B ; Phosphorylation ; Plasma ; Rats* ; RNA, Messenger

Ardipusilloside-I is a natural triterpenoid saponin, which was isolated from Ardisia pusilla A. DC. The aim of the study was to evaluate the stimulation of ardipusilloside-I on gastrointestinal motility in vitro and in vivo. The experiment of smooth muscle contraction directly monitored the contractions of the isolated jejunal segment (IJS) in different contractile states, and the effects of ardipusilloside-I on myosin were measured in the presence of Ca²⁺-calmodulin using the activities of 20 kDa myosin light chain (MLC₂₀) phosphorylation and myosin Mg²⁺-ATPase. The effects of ardipusilloside-I on gastro emptying and intestinal transit in constipation-predominant rats were observed, and the MLCK expression in jejuna of constipated rats was determined by western blot. The results showed that, ardipusilloside-I increased the contractility of IJS in a dose-dependent manner and reversed the low contractile state (LCS) of IJS induced by low Ca²⁺, adrenaline, and atropine respectively. There were synergistic effects on contractivity of IJS between ardipusilloside-I and ACh, high Ca²⁺, and histamine, respectively. Ardipusilloside-I could stimulate the phosphorylation of MLC₂₀ and Mg²⁺-ATPase activities of Ca²⁺- dependent phosphorylated myosin. Ardipusilloside-I also stimulated the gastric emptying and intestinal transit in normal and constipated rats in vivo, respectively, and increased the MLCK expression in the jejuna of constipation-predominant rats. Briefly, the findings demonstrated that ardipusilloside-I could effectively excite gastrointestinal motility in vitro and in vivo.
Animals ; Ardisia ; Atropine ; Blotting, Western ; Epinephrine ; Gastric Emptying ; Gastrointestinal Motility* ; Histamine ; In Vitro Techniques ; Muscle, Smooth* ; Myosin Light Chains* ; Myosin-Light-Chain Kinase* ; Myosins* ; Phosphorylation* ; Rats ; Saponins

The signal transduction pathways within corporal smooth muscle cells are the intracellular molecular mechanisms of corporal smooth muscle tone regulation. Various neurotransmitters activate the membrane receptor proteins or intracellular enzyme pathways and result in the production of extracellular chemical signals. Second messenger molecules and ions transmit and amplify the signals, and subsequently induce the relaxation of smooth muscle cells and penile erection. Therefore, the study of signal transduction in cavernous smooth muscle play an important role in understanding the physiology of erection and the pathophysiology of erectile dysfunction as well as in developing new selective drugs for the treatment of erectile dysfunction.
Calcium ; metabolism ; Humans ; Male ; Muscle, Smooth ; metabolism ; Myosin-Light-Chain Kinase ; physiology ; Penis ; metabolism ; Signal Transduction ; physiology

PURPOSE: RhoA/Rho-kinase regulates vascular tone via a calcium sensitization mechanism. Stimulation of the AT1 receptor by angiotensin (ANG) II activates the Rho A/Rho-kinase signaling pathway. However, its role in corpus cavernosum smooth muscle (PCSM) has not been known. MATERIALS AND METHODS: Isometric tension measurements were performed in rabbit PCSM using a selective Rho-kinase inhibitor, (+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide (Y-27632), and a selective myosin light chain kinase (MLCK) inhibitor, 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine hydrochloride (ML7). RESULTS: Y-27632 significantly attenuated contractions induced by ANG II in a dose-dependent fashion. However, ML7 did not affect the contractile response to ANG II except at high concentration. Y-27632 inhibited contraction in response to phenylephrine (PhE), but ML7 did not. A nitric oxide synthase inhibitor, NG-nitro-L-arginine-methyl ester, did not affect Y-27632-induced relaxation of the strip contracted with PhE. CONCLUSIONS: A G-protein-coupled increase in myofilament Ca2+ sensitivity, mediated through the RhoA/Rho-kinase signaling pathway, is involved in the regulation of the PCSM tone induced by ANG II. The RhoA/Rho-kinase pathway acts in AGN II-induced contraction independent of the NO pathway.
Angiotensin II ; Angiotensins* ; Calcium ; Muscle, Smooth* ; Myofibrils ; Myosin-Light-Chain Kinase ; Nitric Oxide Synthase ; Phenylephrine ; Relaxation ; rho-Associated Kinases*

OBJECTIVETo compare the effect of high frequency oscillatory ventilation (HFOV) and conventional mandatory ventilation (CMV) on the myocardial function of rabbits with inhalation injury.

METHODSSteam inhalation injury model was reproduced in 16 New Zealand albino rabbits. They were randomly divided into CMV group (n = 8) and HFOV group (n = 8) by drawing lots, and they received ventilation in metered volume and HFOV treatment respectively. Heart blood was drawn from rabbits before they were sacrificed 4 hours after treatment to determine the plasma activity of lactate dehydrogenase 1 (LDH1) and creatine phosphorylated kinase (CPK-MB). Myocardial tissue from left ventricle was harvested and homogenized to determine the concentration of TNF-α and IL-8, the activity of caspase-1, and the activity of myosin-light-chain kinase (MLCK) and the ATPase of myosin light chain (MLC-ATPase) by enzyme-linked immunosorbent assay, spectrophotometry, and the nuclide liquid scintillation technique respectively. Part of the myocardial tissue sample was examined pathologically. Data were processed with analysis of variance.

RESULTS(1) The activities of LDH1 and CPK-MB in plasma were obviously higher in CMV group than in HFOV group [(643 ± 108), (342 ± 48) U vs. (233 ± 92), (186 ± 36) U, with F value respectively 10.326 and 9.846, P values all below 0.01]. (2) The contents of TNF-α, IL-8 and the activity of caspase-1 in myocardial tissue homogenate were obviously higher in CMV group than in HFOV group [(181 ± 35), (89 ± 19) pg/g, and (0.56 ± 0.27) g/g protein vs. (94 ± 21), (43 ± 11) pg/g, and (0.24 ± 0.12) g/g protein, with F value respectively 8.239, 7.826, 5.716, P values all below 0.01]. (3) The activities of MLC-ATPase and MLCK were lower in CMV group than in HFOV group [(0.24 ± 0.12) µmol×mg(-1)×min(-1), (3.3 ± 1.1) mmol×mg(-1)×min(-1) vs. (0.48 ± 0.16) µmol×mg(-1)×min(-1), (7.7 ± 1.7) mmol×mg(-1)×min(-1), with F value respectively 4.125, 4.766, P values all below 0.01]. (4) No obvious necrosis, degeneration or inflammatory cell infiltration was observed in myocardial tissue of rabbits in 2 groups under light microscope; but the myocardial fiber was slightly swollen, and it was less marked in the HFOV group.

CONCLUSIONSThe influence of HFOV on myocardial myosin phosphorylation system of rabbits with inhalation injury is less than that of CMV.

Animals ; Burns, Inhalation ; metabolism ; physiopathology ; therapy ; High-Frequency Ventilation ; Myocardium ; metabolism ; Myosin-Light-Chain Kinase ; metabolism ; Rabbits ; Respiration, Artificial

The objective of study was to compare the influences of wortmannin on platelet aggregation and platelet membrane surface glycoproteins GPIb expression after thrombin receptor activation, and to investigate the role of phosphatidylinositol 3-kinase (PI3-K) and myosin light chain kinase (MLCK) in the course of thrombin receptor activation. Peptide SFLLRN (PAR1-AP) and AYPGKF (PAR4-AP) were used for stimulating platelet, and the changes of platelet aggregation and GPIb were analyzed with 100 nmol/L wortmannin (inhibitor of PI3-K) and 10 micromol/L wortmannin (inhibitor of MLCK). The results indicated that the platelet activation was influenced by either concentration of wortmannin in response to PAR stimulation. Platelet aggregation was apparently inhibited by 10 micromol/L wortmannin through both PAR peptides, and was slightly inhibited by 100 nmol/L wortmannin only under PAR1-AP activation. In addition, GPIbalpha internalization was partly inhibited by 100 nmol/L wortmannin in response to PAR1 (p < 0.05 at 1, 2, 5 min) and PAR4 (p < 0.05 at 2, 5, 10 min) activation. Meanwhile, 10 micromol/L wortmannin induced little change for GPIbalpha centralisation in the course of PAR activation, with a delayed restoration of surface GPIbalpha observed under PAR1-AP activation, and no change of GPIbalpha redistribution existed under PAR4-AP activation. It is concluded that the different roles of PI3-K and MLCK exist in the course of thrombin receptor activation. PI3-K accelerates the short course of GPIb centralisation for two PAR signal pathways, while MLCK inhibits the restoration of GPIbalpha in PAR1 pathway.
Adult ; Androstadienes ; pharmacology ; Female ; Humans ; Male ; Myosin-Light-Chain Kinase ; metabolism ; Phosphatidylinositol 3-Kinase ; metabolism ; Platelet Activation ; drug effects ; Platelet Aggregation ; Receptors, Thrombin ; metabolism ; physiology ; Signal Transduction

OBJECTIVE: To study whether the effects of olanzapine on gastrointestinal motility is related to the serotonin antagonism and myosin light chain kinase. METHODS: Male Sprague-Dawley rats were randomly divided into four groups. Olanzapine gavage was performed for each treatment group during the course of 30 continuous days, while the same volume of saline was given to the rats in the control group. Defecation of the rats was observed on days 7 and 30 after olanzapine gavage. The effects of olanzapine on contraction of colonic smooth muscles were observed in ex vivo experiments. A Western blot was used to evaluate expression levels of the serotonin transporter (SERT) and MLCK in colon segments of the rats. RESULTS: ResultsaaCompared to the control group, 5-160 µM of olanzapine could inhibit dose-dependently the contraction of colonic smooth muscle ex vivo experiments. The maximum smooth muscle contraction effects of 5-HT and acetylcholine significantly decreased after treatment with 40-160 µM of olanzapine. Constipation was found in the olanzapine-treated rats on day 7 and have sustained day 30 after gavage. Expression of MLCK in olanzapine-treated rats was significantly decreased, whereas the expression of SERT significantly increased on the day 7, then significantly decreased on the day 30 after olanzapine gavage. CONCLUSION: SERT and MLCK may involve in the inhibition of colonic contraction induced by olanzapine.
Acetylcholine ; Animals ; Antipsychotic Agents ; Blotting, Western ; Colon* ; Constipation ; Defecation ; Gastrointestinal Motility ; Humans ; Male ; Muscle, Smooth ; Myosin Light Chains* ; Myosin-Light-Chain Kinase* ; Myosins* ; Rats ; Rats, Sprague-Dawley ; Serotonin Plasma Membrane Transport Proteins ; Serotonin*

OBJECTIVETo study the role of myosin light chain kinase (MLCK) in intestinal epithelial barrier dysfunction after hypoxia.

METHODSThe Caco-2 monolayers developed with Transwell inserts were exposed to hypoxia for 0 h (NC group), 2, 6, 8, 12 and 24 h (H group), and 6 h hypoxic specimens were treated with 100 mol/L ML-9 (T group). The transepithelial electrical resistance (TER) of monolayers was measured with an ohmmeter. The tight junction protein ZO-1 of monolayers was analyzed by immunofluorescence assay. The protein expressions of phosphorylated myosin light chain (p-MLC) and MLCK were detected by Western blotting.

RESULTSThe TER of monolayers in H group at 6, 8, 12 and 24 h was 422 +/- 17, 427 +/- 27, 403 +/- 40 and 426 +/- 22 ohms respectively, which was significantly lower than that of NC group (451 +/- 27 ohms, P < 0.05). The TER of monolayers in T group was 558 +/- 110 ohms, which was significantly higher than that in H group at each time point ( P < 0.01). The ZO-1 of monolayers in H group at 6 h was irregular in arrangement, with interruptions and rugae, and sawtooth. These abnormalities were ameliorated in T group (regular in arrangement, with little or without ruga and sawtooth). The protein expressions of p-MLC and MLCK in H group at each time point were higher than those in NC group.

CONCLUSIONSIntestinal epithelial barrier dysfunction after hypoxia can be mediated by MLCK.

Caco-2 Cells ; Epithelium ; metabolism ; physiopathology ; Humans ; Hypoxia ; metabolism ; physiopathology ; Intestinal Absorption ; Intestinal Mucosa ; metabolism ; physiopathology ; Intestines ; cytology ; metabolism ; physiopathology ; Myosin Light Chains ; metabolism ; Myosin-Light-Chain Kinase ; metabolism

OBJECTIVETo investigate the effect of combination of interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α) on intestinal epithelial barrier function.

METHODSThe Caco-2 monolayers were cultured in DMEM nutrient solution, and then they were inoculated in 24-well or 6-well plate with Transwell inserts.They were divided into control group (ordinary treatment), IFN-γ group (with addition of 10 ng/mL IFN-γ), TNF-α group (with addition of 10 ng/mL TNF-α), and IFN-γ plus TNF-α group (with addition of 10 ng/mL TNF-α and 10 ng/mL IFN-γ). Monolayers inoculated in 24-well plate were collected for determination of transepithelial electrical resistance (TER) with an ohmmeter at post treatment hour (PTH) 0, 6, 12, 24, 36, and 48, the permeability of monolayers with fluorescein isothiocyanate-labeled dextran (FITC-dextran) tracer method at PTH 48, the distribution and morphological change of tight junction occludin with immunofluorescence assay at PTH 48. Monolayers inoculated in 6-well plate were collected for determination of protein expression of occludin, myosin light chain kinase (MLCK), and phosphorylated MLC (pMLC) with Western blot at PTH 24. Data were processed with one-way analysis of variance and t test.

RESULTS(1) There was no obvious difference in TER in control group at each time point (F = 0.86, P > 0.05). TER in IFN-γ group and TNF-α group were gradually decreased during PTH 6-48, but showed no statistical difference as compared with that at PTH 0 (with F value respectively 1.69, 2.47, P values all above 0.05). TER in IFN-γ plus TNF-α group was significantly decreased from PTH 24 as compared with that at PTH 0 (t = 4.97, P < 0.05) and that in each of the other three groups (F = 11.54, P < 0.05). (2) The permeability of monolayers in IFN-γ plus TNF-α group [(1197 ± 215)pmol] was significantly higher than that in control group, IFN-γ group, and TNF-α group [(303 ± 93), (328 ± 76), (797 ± 177) pmol, with t value respectively 4.8, 5.0, 6.9, P values all below 0.01]. (3) There was no statistical difference in occludin expression at PTH 24 among four groups (F = 0.26, P > 0.05). The occludin in control group at PTH 48 was regular in arrangement, while that in IFN-γ and TNF-α groups was irregular in arrangement. The arrangement of occludin in IFN-γ plus TNF-α group at PTH 48 was interrupted, with obvious redistribution in cytoplasm. (4) The protein expression of pMLC in IFN-γ plus TNF-α group (0.95 ± 0.05) was significantly higher than that in control group, IFN-γ group, or TNF-α group (0.57 ± 0.12, 0.56 ± 0.07, 0.59 ± 0.10, respectively, F = 17.97, P < 0.01). The protein expression of MLCK in IFN-γ plus TNF-α group (1.57 ± 0.36) was also significantly higher than that in control, IFN-γ, TNF-α groups (0.85 ± 0.18, 1.04 ± 0.23, 1.00 ± 0.07, respectively, F = 9.05, P < 0.05).

CONCLUSIONSCombination of IFN-γ and TNF-α can induce intestinal epithelial barrier dysfunction by up-regulating MLCK protein expression and promoting MLC phosphorylation.

Caco-2 Cells ; Epithelial Cells ; drug effects ; metabolism ; Humans ; Interferon-gamma ; pharmacology ; Intestinal Mucosa ; cytology ; physiopathology ; Membrane Proteins ; metabolism ; Myosin Light Chains ; metabolism ; Myosin-Light-Chain Kinase ; metabolism ; Occludin ; Tumor Necrosis Factor-alpha ; pharmacology

Massive burn trauma is characterized by hypovolemic shock induced by the loss of plasma from vessels. The major reasons for this systemic microvascular leakage in burns include an increase in vascular permeability triggered by inflammatory mediators and the increase of vascular hydrostatic pressure caused by vessel dilation. The maintenance of normal vascular permeability depends on the integrity of endothelial barrier function regulated by the interaction of intracellular junctions, cell-matrix adhesion and the cytoskeleton contractile force. This review summarizes some recent discovery in endothelial mechanisms during burn-induced vascular hyperpermeability.
Actins ; metabolism ; Burns ; metabolism ; physiopathology ; Capillary Permeability ; Cytoskeleton ; metabolism ; Endothelium, Vascular ; metabolism ; Humans ; Myosin-Light-Chain Kinase ; metabolism ; rho-Associated Kinases ; metabolism