Journal of Smooth Muscle Research
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Volume 46 , Issue 6
Showing 1-7 articles out of 7 articles from the selected issue
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Review
  • Masaki Sanaka, Koji Nakada
    Type: Review
    Volume 46 (2010) Issue 6 Pages 267-280
    Released: March 26, 2011
    JOURNALS FREE ACCESS
    A stable isotope ([13C]) breath test is a promising method for assessing gastric emptying, but it has not been pervasive yet in Japan. We think that there are some barriers to its popularization, including the uncertainty concerning its theoretical backgrounds, the ambiguity of analyzing and interpreting the data, and the lack of standard protocols for breath sampling. The aim of the present review is to break through these barriers. We hope this article could make the [13C]-gastric breath test more maneuverable for and more accessible to researchers and clinicians.
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Original
  • Yoshimichi Yamamoto, Hikaru Suzuki
    Type: Original
    Volume 46 (2010) Issue 6 Pages 281-291
    Released: March 26, 2011
    JOURNALS FREE ACCESS
    Acetylcholine (ACh)-induced membrane currents were investigated using freshly isolated endothelial layers prepared from the guinea-pig mesenteric artery. Gap junctions were blocked by mefloquine and the whole-cell patch clamp method was applied to individual endothelial cells within each multicellular preparation. While mefloquine effectively blocked the gap junctions, it hyperpolarized the membrane by some 10 mV. As this hyperpolarization was absent when the intracellular Cl concentration was increased, mefloquine may increase the membrane conductance for Cl. Besides this minor hyperpolarizing effect, mefloquine did not have serious side effects and ACh could activate a sustained outward current producing a membrane hyperpolarization at concentrations as low as 100 nM. At the beginning of ACh application, the reversal potential of the ACh-induced current was around the equilibrium potential for K+ indicating that this was a K+ current. The reversal potential then gradually became less negative suggesting that other ionic conductances with less negative equilibrium potentials were involved. As the ACh-induced outward current was completely blocked by charybdotoxin (CTX, 100 nM), this current seemed to be due to CTX-sensitive K+ channels, possibly IKCa channels. After the K+ current had been blocked, ACh gradually activated the membrane current which reversed the polarity at around –10 mV, which was most likely due to Ca2+-activated non-selective cation channels. These ionic conductances may be responsible for the variety in agonist-induced membrane responses observed in different types of vascular preparations.
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  • Hiroyuki Fujimoto, Yuhsuke Shigemasa, Hikaru Suzuki
    Type: Original
    Volume 46 (2010) Issue 6 Pages 293-308
    Released: March 26, 2011
    JOURNALS FREE ACCESS
    The properties of spontaneous contractions and their modulation by transmural nerve stimulation (TNS) were investigated in circular smooth muscle preparations isolated from the “pacemaker area” in the flexure region of the guinea-pig colon. Four types of preparation were made; mucosal layer removed preparations, mucosal and submucosal layer removed preparations (submucosal layer removed preparations), longitudinal muscle removed preparations, and preparations with all layers attached (intact preparations). Intact and mucosal layer removed preparations periodically generated two types of phasic contractions; large contractions at a low frequency (about 2 times per min) and small contractions at a higher frequency (about 13 times per min). Submucosal layer removed preparations only produced large contractions, while longitudinal muscle removed preparations only produced small contractions. Both the amplitude and frequency of the large contractions were significantly inhibited by atropine, but were not markedly modulated by Nω-nitro-L-arginine (L-NA) in either intact, mucosal layer removed or submucosal layer removed preparations. Small contractions were not significantly modulated by atropine or L-NA in any type of preparation. In both intact and mucosal layer removed preparations, TNS (1 Hz frequency, for 2–3 min) increased the amplitude and/or frequency of large contractions, but caused no significant change in small contractions. TNS also increased the amplitude and/or frequency of large contractions in submucosal layer removed preparations, but did not significantly modulate small contractions in longitudinal muscle removed preparations. Exogenously applied acetylcholine (>10–7 M) enhanced, while sodium nitroprusside (>10–8 M) inhibited, the amplitude and frequency of both types of contraction, in a concentration-dependent manner. The results suggest that the large contractions were elicited by interstitial cells distributed in the myenteric layer (ICC-MP), while the small contractions were elicited by ICC distributed in the submuscular plexus layer (ICC-SMP). Intramural nerves mainly modulated the activity of ICC-MP, while neural regulation of ICC-SMP was weak.
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  • Héctor Ponce-Monter, Eduardo Fernández-Martínez, ...
    Type: Original
    Volume 46 (2010) Issue 6 Pages 309-319
    Released: March 26, 2011
    JOURNALS FREE ACCESS
    Aloysia triphylla is traditionally utilized for the treatment of menstrual colic (primary dysmenorrhea) in Mexico. Citral is the main chemical component found in Aloysia triphylla leaves extract. Primary dysmenorrhea is a very frequent gynecological disorder in menstruating women, affecting 30–60% of them. It is usually treated with non-steroidal anti-inflammatory drugs (NSAIDs); although their effect is rapid, they possess many side effects. Due to these shortcomings, Mexican folk therapy is considered as a feasible alternative. The effects of the hexane extract of Aloysia triphylla and citral on uterine contractions were evaluated in vitro as well as their anti-inflammatory properties and gastric wound capabilities were assessed in vivo. The inhibitory effects on the contractions were analyzed using isolated uterus strips from estrogen primed rats. Contractions were induced by KCl 60 mM, oxytocin 10 mIU/mL, charbacol 10 μM and PGF 5 μM. The anti-inflammatory effect was assessed on carrageenan-induced rat hind paw edema model. The inhibitory concentration-50 (IC50) of the hexane extract of Aloysia triphylla upon each contractile response was for KCl 44.73 ± 2.48 μg/mL, oxytocin 42.16 ± 3.81 μg/mL, charbacol 41.87 ± 1.73 μg/mL and PGF 28.70 ± 2.40 μg/mL in a concentration-dependent way. The extract of Aloysia triphylla produced a significant inhibitory effect on PGF-induced contraction compared to its inhibitory actions on the others. Citral exhibited the same inhibitory effect on the contraction induced by PGF. The oral administration of the extract (100–800 mg/kg) and citral (100–800 mg/kg) showed anti-inflammatory activity; furthermore, the maximal dose utilized did not produce gastric injury. These results were compared with anti-inflammatory effects and gastric damage produced by 30 mg/kg of indomethacin p.o. The spasmolytic and anti-inflammatory effects support the traditional use of Aloysia triphylla leaves in the treatment of the primary dysmenorrhea in Mexican communities.
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Errata
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