Effect of Kaempferol on Modulation of Vascular Contractility Mainly through PKC and CPI-17 Inactivation.

In this study, we investigated the efficacy of kaempferol (a flavonoid found in plants and plant-derived foods such as kale, beans, tea, spinach and broccoli) on vascular contractibility and aimed to clarify the detailed mechanism underlying the relaxation. Isometric contractions of divested muscles were stored and linked with western blot analysis which was carried out to estimate the phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and phosphorylation-dependent inhibitory protein for myosin phosphatase (CPI-17) and to estimate the effect of kaempferol on the RhoA/ROCK/CPI-17 pathway. Kaempferol conspicuously impeded phorbol ester-, fluoride- and a thromboxane mimetic-derived contractions regardless of endothelial nitric oxide synthesis, indicating its direct effect on smooth muscles. It also conspicuously impeded the fluoride-derived elevation in phospho-MYPT1 rather than phospho-CPI-17 levels and phorbol 12,13-dibutyrate-derived increase in phospho-CPI-17 and phospho-ERK1/2 levels, suggesting the depression of PKC and MEK activities and subsequent phosphorylation of CPI-17 and ERK1/2. Taken together, these outcomes suggest that kaempferol-derived relaxation incorporates myosin phosphatase retrieval and calcium desensitization, which appear to be modulated by CPI-17 dephosphorylation mainly through PKC inactivation.

Benzyl Isothiocyanate-Induced Cytotoxicity via the Inhibition of Autophagy and Lysosomal Function in AGS Cells.

Gastric adenocarcinoma is among the top causes of cancer-related death and is one of the most commonly diagnosed carcinomas worldwide. Benzyl isothiocyanate (BITC) has been reported to inhibit the gastric cancer metastasis. In our previous study, BITC induced apoptosis in AGS cells. The purpose of the present study was to investigate the effect of BITC on autophagy mechanism in AGS cells. First, the AGS cells were treated with 5, 10, or 15 µM BITC for 24 h, followed by an analysis of the autophagy mechanism. The expression level of autophagy proteins involved in different steps of autophagy, such as LC3B, p62/SQSTM1, Atg5-Atg12, Beclin1, p-mTOR/mTOR ratio, and class III PI3K was measured in the BITC-treated cells. Lysosomal function was investigated using cathepsin activity and Bafilomycin A1, an autophagy degradation stage inhibitor. Methods including qPCR, western blotting, and immunocytochemistry were employed to detect the protein expression levels. Acridine orange staining and omnicathepsin assay were conducted to analyze the lysosomal function. siRNA transfection was performed to knock down the LC3B gene. BITC reduced the level of autophagy protein such as Beclin 1, class III PI3K, and Atg5-Atg12. BITC also induced lysosomal dysfunction which was shown as reducing cathepsin activity, protein level of cathepsin, and enlargement of acidic vesicle. Overall, the results showed that the BITC-induced AGS cell death mechanism also comprises the inhibition of the cytoprotective autophagy at both initiation and degradation steps.

The Effect of Galangin on the Regulation of Vascular Contractility via the Holoenzyme Reactivation Suppressing ROCK/CPI-17 rather than PKC/CPI-17.

In this study, we investigated the influence of galangin on vascular contractibility and to determine the mechanism underlying the relaxation. Isometric contractions of denuded aortic muscles were recorded and combined with western blot analysis which was performed to measure the phosphorylation of phosphorylation-dependent inhibitory protein of myosin phosphatase (CPI-17) and myosin phosphatase targeting subunit 1 (MYPT1) and to evaluate the effect of galangin on the RhoA/ROCK/CPI-17 pathway. Galangin significantly inhibited phorbol ester-, fluoride- and thromboxane mimetic-induced vasoconstrictions regardless of endothelial nitric oxide synthesis, suggesting its direct effect on vascular smooth muscle. Galangin significantly inhibited the fluoride-dependent increase in pMYPT1 and pCPI-17 levels and phorbol 12,13-dibutyrate-dependent increase in pERK1/2 level, suggesting repression of ROCK and MEK activity and subsequent phosphorylation of MYPT1, CPI-17 and ERK1/2. Taken together, these results suggest that galangin-induced relaxation involves myosin phosphatase reactivation and calcium desensitization, which appears to be mediated by CPI-17 dephosphorylation via not PKC but ROCK inactivation.

Polysaccharide-Rich Extract of Phragmites rhizome Attenuates Water Immersion Stress and Forced Swimming Fatigue in Rodent Animal Model.

Our study aimed to investigate the effects of the polysaccharide-rich extract of Phragmites rhizoma (PEP) against water immersion restraint (WIR) stress and forced swimming-induced fatigue. Exposure to WIR stress significantly increased the ulcer index, bleeding score, the weight of the adrenal gland, blood glucose concentrations, total cholesterol, cortisol, and creatine kinase (CK). The weight of the spleen decreased significantly. In addition, myeloperoxidase (MPO) and thiobarbituric acid-reactive substance (TBARS) were significantly upregulated by WIR stress. The antioxidative factors such as glutathione (GSH) and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the stomach were decreased by WIR stress. Alterations induced by WIR stress were effectively reversed by pretreatment with PEP. The swimming endurance capacity of mice was significantly prolonged by the oral administration of PEP. Swimming-induced fatigue significantly reduced the body weight; however, the injection of PEP inhibited the decrease of body weight. The PEP-treated group had significantly lower CK levels in plasma, an indicator of muscle damage. These results indicated that PEP has anti-stress and anti-fatigue effects, which are mediated by suppressing the hyperactivation of the hypothalamus-pituitary-adrenal axis, and antagonism of the oxidative damages induced by WIR stress and prolonged swimming times.

Humulus japonicus Extracts Protect Against Lipopolysaccharide/d-Galactosamine-Induced Acute Liver Injury in Rats.

It has been described that Humulus japonicus has potential antituberculosis and anti-inflammatory effects. The antiaging activity of H. japonicus extract (HJE) was also examined not only in yeast but also in human fibroblast cells. We evaluated the protective effect of HJE on hepatotoxicity in this study. We demonstrated the expression of antioxidative enzyme and cytokines in plasma. The vehicle control group received orally administered normal saline. Acute hepatotoxicity rat model was induced by lipopolysaccharide (LPS) (30 µg/kg) and d-galactosamine (D-GalN) (500 mg/kg) by intraperitoneal injection. The positive control group received orally administered silymarin (10 mg/kg). Three HJE groups received 8, 16, and 32 mg/kg. The blood samples were prepared to evaluate malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) level to examine oxidative stress, and hepatic tissue was assayed for myeloperoxidase (MPO). Aspartate aminotransferase (AST), alanine aminotransferase (ALT), and tumor necrosis factor-α (TNF-α) activities were also assayed to examine liver cell viability. Pretreatment with HJE decreased levels of AST, ALT, MDA, MPO, and TNF-α and increased levels of SOD and CAT compared with the LPS/D-GalN-treated group. These results suggested that HJE has the potential to reduce oxidative damage and inflammatory reactions in LPS/D-GalN-induced liver injury in the rat model. It can also increase survival rate in LPS/D-GalN-induced hepatotoxicity rat models.

The change of signaling pathway on the electrical stimulated contraction in streptozotocin-induced bladder dysfunction of rats.

Bladder dysfunction is a common complication of diabetes mellitus (DM). However, there have been a few studies evaluating bladder smooth muscle contraction in DM in the presence of pharmacological inhibitors. In the present study, we compared the contractility of bladder smooth muscle from normal rats and DM rats. Furthermore, we utilized pharmacological inhibitors to delineate the mechanisms underlying bladder muscle differences between normal and DM rats. DM was established in 14 days after using a single injection of streptozotocin (65 mg/kg, intraperitoneal) in Sprague-Dawley rats. Bladder smooth muscle contraction was induced electrically using electrical field stimulation consisting of pulse trains at an amplitude of 40 V and pulse duration of 1 ms at frequencies of 2-10 Hz. In this study, the pharmacological inhibitors atropine (muscarinic receptor antagonist), U73122 (phospholipase C inhibitor), DPCPX (adenosine A1 receptor antagonist), udenafil (PDE5 inhibitor), prazosin (α1-receptor antagonist), verapamil (calcium channel blocker), and chelerythrine (protein kinase C inhibitor) were used to pretreat bladder smooth muscles. It was found that the contractility of bladder smooth muscles from DM rats was lower than that of normal rats. In addition, there were significant differences in percent change of contractility between normal and DM rats following pretreatment with prazosin, udenafil, verapamil, and U73122. In conclusion, we suggest that the decreased bladder muscle contractility in DM rats was a result of perturbations in PLC/IP3-mediated intracellular Ca2+ release and PDE5 activity.

Cytoprotective effect of eupatilin against indomethacin-induced damage in feline esophageal epithelial cells: relevance of HSP27 and HSP70.

Indomethacin is a non-steroidal anti-inflammatory drug with clearly known side effects on the gastrointestinal tract. The purpose of the present study was to investigate whether eupatilin inhibit cell injury induced by indomethacin in cultured feline esophageal epithelial cells (EECs). EECs were used to investigate the ability of eupatilin to induce the expression of heat shock proteins (HSP27 and HSP70) and analyze its cytoprotective effect against indomethacin-induced damage. The treatment of EECs with indomethacin for 8 h decreased cell viability. Western blot analysis showed that the levels of HSPs gradually decreased in cells treated with indomethacin, while eupatilin treatment increased the levels of HSPs. When treated with both indomethacin and eupatilin, the levels of HSPs increased rapidly, and were maintained at 130-140%. In addition, treatment with the specific inhibitors of PTK, PKC, PLC, p38 MAPK, JNKs, and PI3K attenuated the eupatilin-induced expression of HSPs. Pretreatment of EECs with the inhibitors of protein synthesis, actinomycin D or cycloheximide, attenuated the cytoprotective effect of eupatilin on indomethacin-induced cell damage. Reactive oxygen species production was upregulated by indomethacin, but downregulated by eupatilin. Taken together, it was suggested that HSPs were partly responsible for the eupatilin-mediated cytoprotective activity against the indomethacin-induced damage in EECs.

Recent advances in pharmacological research on the management of irritable bowel syndrome.

Irritable bowel syndrome (IBS), a common gastrointestinal (GI) disorder, is associated with various factors, including lifestyle, infection, stress, intestinal flora, and related diseases. The pharmacotherapeutic stimulation of receptors and downstream signaling pathways is effective in reducing IBS symptoms; however, it is still associated with adverse effects. Various receptors related to GI motility and visceral hypersensitivity should be considered to enhance the benefit/risk ratio of IBS treatments. This review discusses recent pharmacological advances in IBS management. Several receptors related to GI motility and abdominal pain are investigated in various angles. 5-Hydroxytryptamine (5-HT) is an important neurotransmitter that activates the colonic mucosal 5-HT4 receptor without causing severe cardiovascular adverse effects. The clinical potential of ramosetron for diarrhea-predominant IBS has been suggested because of a lower risk of ischemic colitis than conventional 5-HT3 receptor antagonists. Toll-like receptors (TLRs), especially TLR2 and TLR4, show a significant effect on the post-infection symptoms and lipopolysaccharide-mediated regulation of GI motility. Histamine is a well-known nitrogenous compound that regulates inflammatory responses and visceral hypersensitivity. Histamine 1 receptor-mediated sensitization of the transient receptor potential vanilloid 1 is associated with IBS. Pharmacological approaches based on these signaling pathways could be useful in the development of novel IBS treatments.

Effect of Sphingosine-1-Phosphate on Intracellular Free Ca²âº in Cat Esophageal Smooth Muscle Cells.

A comprehensive collection of proteins senses local changes in intracellular Ca²âº concentrations ([Ca²âº]i) and transduces these signals into responses to agonists. In the present study, we examined the effect of sphingosine-1-phosphate (S1P) on modulation of intracellular Ca²âº concentrations in cat esophageal smooth muscle cells. To measure [Ca²âº]i levels in cat esophageal smooth muscle cells, we used a fluorescence microscopy with the Fura-2 loading method. S1P produced a concentration-dependent increase in [Ca²âº]i in the cells. Pretreatment with EGTA, an extracellular Ca²âº chelator, decreased the S1P-induced increase in [Ca²âº]i, and an L-type Ca²âº-channel blocker, nimodipine, decreased the effect of S1P. This indicates that Ca²âº influx may be required for muscle contraction by S1P. When stimulated with thapsigargin, an intracellular calcium chelator, or 2-Aminoethoxydiphenyl borate (2-APB), an InsP3 receptor blocker, the S1P-evoked increase in [Ca²âº]i was significantly decreased. Treatment with pertussis toxin (PTX), an inhibitor of Gi-protein, suppressed the increase in [Ca²âº]i evoked by S1P. These results suggest that the S1P-induced increase in [Ca²âº]i in cat esophageal smooth muscle cells occurs upon the activation of phospholipase C and subsequent release of Ca²âº from the InsP3-sensitive Ca²âº pool in the sarcoplasmic reticulum. These results suggest that S1P utilized extracellular Ca²âº via the L type Ca²âº channel, which was dependent on activation of the S1P4 receptor coupled to PTX-sensitive Gi protein, via phospholipase C-mediated Ca²âº release from the InsP3-sensitive Ca²âº pool in cat esophageal smooth muscle cells.

Endothelium Independent Effect of Pelargonidin on Vasoconstriction in Rat Aorta.

In this study, we investigated the effects of pelargonidin, an anthocyanidin found in many fruits and vegetables, on endothelium-independent vascular contractility to determine the underlying mechanism of relaxation. Isometric contractions of denuded aortic muscles from male rats were recorded, and the data were combined with those obtained in western blot analysis. Pelargonidin significantly inhibited fluoride-, thromboxane A2-, and phorbol ester-induced vascular contractions, regardless of the presence or absence of endothelium, suggesting a direct effect of the compound on vascular smooth muscles via a different pathway. Pelargonidin significantly inhibited the fluoride-dependent increase in the level of myosin phosphatase target subunit 1 (MYPT1) phosphorylation at Thr-855 and the phorbol 12,13-dibutyrate-dependent increase in the level of extracellular signal-regulated kinase (ERK) 1/2 phosphorylation at Thr202/Tyr204, suggesting the inhibition of Rho-kinase and mitogen-activated protein kinase kinase (MEK) activities and subsequent phosphorylation of MYPT1 and ERK1/2. These results suggest that the relaxation effect of pelargonidin on agonist-dependent vascular contractions includes inhibition of Rho-kinase and MEK activities, independent of the endothelial function.

The protective mechanism of QGC in feline esophageal epithelial cells by interleukin-1ß treatment.

In a previous study, Quercetin-3-O-ß-D-glucuronopyranoside (QGC) has anti-oxidative and anti-inflammatory effects in vivo. QGC is a flavonoid glucoside extracted from Rumex Aquaticus. We investigated the downstream target proteins involved in IL-1ß-stimulated ROS production and the ability of QGC to inhibit ROS production. Cell viability was determined using the MTT reduction assay. Western blot analysis was performed with antibodies to investigate the activation of three MAPKs, NF-κB, and phosphorylated IκB-α (pIB), and the expression of COX-2. 2',7'-dichlorofluorescin diacetate was used to detect the generation of intracellular ROS species. When the cells were exposed to media containing IL-1ß for 18 h, cell viability was not affected. QGC did not reduce the COX-2 expression induced by IL-1ß. However; QGC attenuated the production of intracellular ROS induced by IL-1ß. IL-1ß increased the expression of ERK, p38 MAPK, and pIB, and nuclear translocation of NF-κB were recovered by the ROS scavenger N-acetyl-L-cysteine (NAC) and QGC, but not by the NADPH oxidase inhibitor diphenylene iodonium. Pretreatment of cells with the ERK inhibitor PD98059, the p38 MAPK inhibitor SB202190, NAC, and QGC attenuated nuclear translocation of NF-κB and activation of pIB. QGC has a scavenging effect on cytokine-induced ROS production, thereby preventing its downstream effects, nuclear translocation of NF-κB, and activation of pIB is mediated by activation of ERK and p38 MAPK, although QGC does not inhibit IL-1ß-stimulated COX-2 expression in feline esophageal epithelial cells. The data suggest that QGC exerts anti-oxidative effects and inhibitory effects against esophageal epithelial cells signals by the action of IL-1ß treatment.

The p90rsk-mediated signaling of ethanol-induced cell proliferation in HepG2 cell line.

Ribosomal S6 kinase is a family of serine/threonine protein kinases involved in the regulation of cell viability. There are two subfamilies of ribosomal s6 kinase, (p90rsk, p70rsk). Especially, p90rsk is known to be an important downstream kinase of p44/42 MAPK. We investigated the role of p90rsk on ethanol-induced cell proliferation of HepG2 cells. HepG2 cells were treated with 10~50 mM of ethanol with or without ERK and p90rsk inhibitors. Cell viability was measured by MTT assay. The expression of pERK1, NHE1 was measured by Western blots. The phosphorylation of p90rsk was measured by ELISA kits. The expression of Bcl-2 was measured by qRT-PCR. When the cells were treated with 10~30 mM of ethanol for 24 hour, it showed significant increase in cell viability versus control group. Besides, 10~30 mM of ethanol induced increased expression of pERK1, p-p90rsk, NHE1 and Bcl-2. Moreover treatment of p90rsk inhibitor attenuated the ethanol-induced increase in cell viability and NHE1 and Bcl-2 expression. In summary, these results suggest that p90rsk, a downstream kinase of ERK, plays a stimulatory role on ethanol-induced hepatocellular carcinoma progression by activating anti-apoptotic factor Bcl-2 and NHE1 known to regulate cell survival.

The comparative effects of aminoglycoside antibiotics and muscle relaxants on electrical field stimulation response in rat bladder smooth muscle.

It has been reported that several aminoglycoside antibiotics have a potential of prolonging the action of non-depolarizing muscle relaxants by drug interactions acting pre-synaptically to inhibit acetylcholine release, but antibiotics itself also have a strong effect on relaxing the smooth muscle. In this study, four antibiotics of aminoglycosides such as gentamicin, streptomycin, kanamycin and neomycin were compared with skeletal muscle relaxants baclofen, tubocurarine, pancuronium and succinylcholine, and a smooth muscle relaxant, papaverine. The muscle strips isolated from the rat bladder were stimulated with pulse trains of 40 V in amplitude and 10 s in duration, with pulse duration of 1 ms at the frequency of 1-8 Hz, at 1, 2, 4, 6, 8 Hz respectively. To test the effect of four antibiotics on bladder smooth muscle relaxation, each of them was treated cumulatively from 1 µM to 0.1 mM with an interval of 5 min. Among the four antibiotics, gentamicin and neomycin inhibited the EFS response. The skeletal muscle relaxants (baclofen, tubocurarine, pancuronium and succinylcholine) and inhibitory neurotransmitters (GABA and glycine) did not show any significant effect. However, papaverine, had a significant effect in the relaxation of the smooth muscle. It was suggested that the aminoglycoside antibiotics have inhibitory effect on the bladder smooth muscle.

KHG26792 Inhibits Melanin Synthesis in Mel-Ab Cells and a Skin Equivalent Model.

The purpose of this study is to characterize the effects of KHG26792 (3-(naphthalen-2-yl(propoxy) methyl)azetidine hydrochloride), a potential skin whitening agent, on melanin synthesis and identify the underlying mechanism of action. Our data showed that KHG26792 significantly reduced melanin synthesis in a dose-dependent manner. Additionally, KHG26792 downregulated microphthalmia-associated transcription factor (MITF) and tyrosinase, the rate-limiting enzyme in melanogenesis, although tyrosinase was not inhibited directly. KHG26792 activated extracellular signal-regulated kinase (ERK), whereas an ERK pathway inhibitor, PD98059, rescued KHG26792-induced hypopigmentation. These results suggest that KHG26792 decreases melanin production via ERK activation. Moreover, the hypopigmentary effects of KHG26792 were confirmed in a pigmented skin equivalent model using Cervi cornus Colla (deer antler glue), in which the color of the pigmented artificial skin became lighter after treatment with KHG26792. In summary, our findings suggest that KHG26792 is a novel skin whitening agent.

The inhibitory effect of vitexin on the agonist-induced regulation of vascular contractility.

The present study was undertaken to investigate the influence of vitexin on vascular smooth muscle contractility and to determine the mechanism involved. Intact or denuded aortic rings from male rats were used and isometric contractions were recorded and combined with molecular experiments. Vitexin more significantly relaxed phorbol ester-induced vascular contraction than thromboxane A2 or fluoride-induced contraction suggesting as a possible anti-hypertensive on the agonist-induced vascular contraction regardless of endothelial nitric oxide synthesis. Furthermore, vitexin significantly inhibited phorbol ester-induced increases in pERK1/2 levels. On the other hand, it did not significantly inhibit thromboxane A2-induced increases in pMYPT1 levels suggesting the mechanism involving the primarily inhibition of MEK activity and the subsequent phosphorylation of ERK1/2. This study provides evidence regarding the mechanism underlying the relaxation effect of vitexin on agonist-induced vascular contraction regardless of endothelial function.

Effect of ECQ on Iodoacetamide-Induced Chronic Gastritis in Rats.

This study investigated effect of extract containing quercetin-3-O-ß-D-glucuronopyranoside from Rumex Aquaticus Herba (ECQ) against chronic gastritis in rats. To produce chronic gastritis, the animals received a daily intra-gastric administration of 0.1 ml of 0.15% iodoacetamide (IA) solution for 7 days. Daily exposure of the gastric mucosa to IA induced both gastric lesions and significant reductions of body weight and food and water intake. These reductions recovered with treatment with ECQ for 7 days. ECQ significantly inhibited the elevation of the malondialdehyde levels and myeloperoxidase activity, which were used as indices of lipid peroxidation and neutrophil infiltration. ECQ recovered the level of glutathione, activity of superoxide dismutase (SOD), and expression of SOD-2. The increased levels of total NO concentration and iNOS expression in the IA-induced chronic gastritis were significantly reduced by treatment with ECQ. These results suggest that the ECQ has a therapeutic effect on chronic gastritis in rats by inhibitory actions on neutrophil infiltration, lipid peroxidation and various steps of reactive oxygen species (ROS) generation.

The effects of pigs' feet consumption on lactation.

Pigs' feet are traditionally consumed by Korean women to increase milk production during lactation. In this study, we evaluated the perceived effectiveness and safety of consuming pigs' feet. Parous women were recruited to complete survey questionnaires in South Korea. Of the 516 respondents, 188 (36%) claimed they consumed pigs' feet. One-hundred twenty women (64%) who consumed pigs' feet reported experiencing an increase in breast milk production. Seventy-three (61%) women from this same group exclusively breastfed. In contrast, 16 (25%) of 65 respondents who did not embrace the same purported effect of pigs' feet indicated that they solely breastfed. Ninety-eight (82%) respondents who consumed pigs' feet and reported galactagoguic effects would recommend its use. Study findings reveal that the majority of women who consume pigs' feet believe in its milk-promoting effects. The results of this study suggest that further investigation of the galactagoguic effects of pigs' feet via conduction of an experimental study is warranted.

Inhibition of melanogenesis by Xanthium strumarium L.

Xanthium strumarium L. (Asteraceae) is traditionally used in Korea to treat skin diseases. In this study, we investigated the effects of a X. strumarium stem extract on melanin synthesis. It inhibited melanin synthesis in a concentration-dependent manner, but it did not directly inhibit tyrosinase, the rate-limiting melanogenic enzyme, and instead downregulated microphthalmia-associated transcription factor (MITF) and tyrosinase expression. MITF, the master regulator of pigmentation, is a target of the Wnt signaling pathway, which includes glycogen synthase kinase 3ß (GSK3ß) and ß-catenin. Hence, the influence of X. strumarium stem extract on GSK3ß and ß-catenin was further investigated. X. strumarium induced GSK3ß phosphorylation (inactivation), but the level of ß-catenin did not change. Moreover, a specific GSK3ß inhibitor restored X. strumarium-induced melanin reduction. Hence, we suggest that X. strumarium inhibits melanin synthesis through downregulation of tyrosinase via GSK3ß phosphorylation.

MLCK and PKC Involvements via Gi and Rho A Protein in Contraction by the Electrical Field Stimulation in Feline Esophageal Smooth Muscle.

We have shown that myosin light chain kinase (MLCK) was required for the off-contraction in response to the electrical field stimulation (EFS) of feline esophageal smooth muscle. In this study, we investigated whether protein kinase C (PKC) may require the on-contraction in response to EFS using feline esophageal smooth muscle. The contractions were recorded using an isometric force transducer. On-contraction occurred in the presence of N(G)-nitro-L-arginine methyl ester (L-NAME), suggesting that nitric oxide acts as an inhibitory mediator in smooth muscle. The excitatory composition of both contractions was cholinergic dependent which was blocked by tetrodotoxin or atropine. The on-contraction was abolished in Ca(2+)-free buffer but reappeared in normal Ca(2+)-containing buffer indicating that the contraction was Ca(2+) dependent. 4-aminopyridine (4-AP), voltage-dependent K(+) channel blocker, significantly enhanced on-contraction. Aluminum fluoride (a G-protein activator) increased on-contraction. Pertussis toxin (a G(i) inactivator) and C3 exoenzyme (a rhoA inactivator) significantly decreased on-contraction suggesting that Gi or rhoA protein may be related with Ca(2+) and K(+) channel. ML-9, a MLCK inhibitor, significantly inhibited on-contraction, and chelerythrine (PKC inhibitor) affected on the contraction. These results suggest that endogenous cholinergic contractions activated directly by low-frequency EFS may be mediated by Ca(2+), and G proteins, such as Gi and rhoA, which resulted in the activation of MLCK, and PKC to produce the contraction in feline distal esophageal smooth muscle.

The Inhibitory Effect of Quercetin-3-O-beta-D-Glucuronopyranoside on Gastritis and Reflux Esophagitis in Rats.

It was evaluated the inhibitory action of quercetin-3-O-beta-D-glucuronopyranoside (QGC) on reflux esophagitis and gastritis in rats. QGC was isolated from the herba of Rumex Aquaticus. Reflux esophagitis or gastritis was induced surgically or by administering indomethacin, respectively. Oral QGC decreased ulcer index, injury area, gastric volume, and acid output and increased gastric pH as compared with quercetin. Furthermore, QGC significantly decreased gastric lesion sizes induced by exposing the gastric mucosa to indomethacin. Malondialdehyde levels were found to increase significantly after inducing reflux esophagitis, and were reduced by QGC, but not by quercetin or omeprazole. These results show that QGC can inhibit reflux esophagitis and gastritis in rats.