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Longitudinal Muscle Strips (longitudinal + muscle_strip)

Distribution by Scientific Domains

Medical Sciences	83%

Selected Abstracts

Nitric oxide mediates the inhibitory effect of ethanol on the motility of isolated longitudinal muscle of proximal colon in rats

NEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2007
S. L. Wang
Abstract, The aim of the present study was to investigate the effect of ethanol on colon motility in rats and to test the possibility that nitric oxide (NO) mediates this effect. Proximal colon longitudinal muscle strips (LM) (8 × 3 mm) cut parallel to the longitudinal muscle fibres of the colon were isolated and mounted in an organ bath. Ethanol (0.57, 0.87 and 1.30 mmol L,1) dose-dependently inhibited the motility of LM. Longitudinal muscle strips from female rats were more sensitive to the inhibitory effect of ethanol than that from male rats. L-NAME (N -nitro- l -arginine methyl ester) (100 ,mol L,1), AG (aminoguanidine) (10 ,mol L,1), ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one) (10 ,mol L,1) and PTIO (2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide) (200 ,mol L,1) partly blocked the inhibitory effect of ethanol on LM. Pretreatment with L-NAME, AG, ODQ and PTIO abolished the sex difference of the inhibitory effect of ethanol on LM. Tetrodotoxin (TTX) (10 ,mol L,1) partly blocked the inhibitory effect but did not influence the sex difference. The relaxation of LM induced by SNP (sodium nitroprusside) (0.1,10 ,mol L,1) in female rats was greater than that in male rats. In conclusion, ethanol inhibited the colon motility in vitro. This inhibitory effect on LM was mediated by NO through the iNOS , NO , cGMP pathway. [source]

Inhibition of carbachol-evoked oscillatory currents by the NO donor sodium nitroprusside in guinea-pig ileal myocytes

EXPERIMENTAL PHYSIOLOGY, Issue 4 2005
Seung-Soo Chung
The effect of sodium nitroprusside (SNP) on carbachol (CCh)-evoked inward cationic current (Icat) oscillations in guinea-pig ileal longitudinal myocytes was investigated using the whole-cell patch-clamp technique and permeabilized longitudinal muscle strips. SNP (10 ,m) completely inhibited Icat oscillations evoked by 1 ,m CCh. 1H-(1,2,4) Oxadiazole [4,3-a] quinoxaline-1-one (ODQ; 1 ,m) almost completely prevented the inhibitory effect of SNP on Icat oscillations. 8-Bromo-guanosine 3,,5,-cyclic monophosphate (8-Br-cGMP; 30 ,m) in the pipette solution completely abolished Icat oscillations. However, a pipette solution containing Rp-8-Br-cGMP (30 ,m) almost completely abolished the inhibitory effect of SNP on Icat oscillations. When the intracellular calcium concentration ([Ca2+]i) was held at a resting level using BAPTA (10 mm) and Ca2+ (4.6 ,m) in the pipette solution, CCh (1 ,m) evoked only the sustained component of Icat without any oscillations and SNP did not affect the current. A high concentration of inositol 1,4,5-trisphosphate (IP3; 30 ,m) in the patch pipette solutions significantly reduced the inhibitory effect of SNP (10 ,m) on Icat oscillations. SNP significantly inhibited the Ca2+ release evoked by either CCh or IP3 but not by caffeine in permeabilized preparations of longitudinal muscle strips. These results suggest that the inhibitory effects of SNP on Icat oscillations are mediated, in part, by functional modulation of the IP3 receptor, and not by the inhibition of cationic channels themselves or by muscarinic receptors in the plasma membrane. This inhibition seems to be mediated by an increased cGMP concentration in a protein kinase G-dependent manner. [source]

Ethanol Upregulates iNOS Expression in Colon Through Activation of Nuclear Factor-kappa B in Rats

ALCOHOLISM, Issue 1 2010
Chao Wang
Background:, Alcohol inhibits colonic motility but the mechanism is unknown. The goal of this study was to test the possibility that nuclear factor-kappa B (NF-,B) is involved in the upregulation of inducible nitric oxide synthase (iNOS) expression induced by ethanol in colon. Methods:, The isometric contraction of longitudinal muscle strips of proximal colon (LP) was monitored by polygraph. Western blot analysis was used to measure the amount of iNOS and I-,B in the cytoplasm and P65 in the nucleus. Immunohistochemistry was applied to locate iNOS in colon. Results:, Ethanol (87mM) inhibited the contraction of LP. Pretreatment of S-methylisothioure (SMT) (1 mM), a specific iNOS inhibitor, Pyrrolidine dithiocarbamate (PDTC) (10 mM) and BAY11-7082(10 mM), specific inhibitors of NF-,B significantly reversed the inhibitory effect of ethanol on LP contraction. Ethanol increased the amount of iNOS and content of NO in colon, and these effects were attenuated by pretreatment of PDTC. Following ethanol administration, the amount of I-,B in the cytoplasm decreased, but that of P65, the subunit of NF-,B in the nucleus, increased. The iNOS was located in the cell body of myenteric plexus in colon. Conclusion:, Ethanol inhibited the contraction of LP in colon mainly through activation of NF-,B, the subsequent upregulation of iNOS expression and increase of NO release in myenteric plexus. [source]

Nitric oxide mediates the inhibitory effect of ethanol on the motility of isolated longitudinal muscle of proximal colon in rats

Fibre-free diet leads to impairment of neuronally mediated muscle contractile response in rat distal colon

NEUROGASTROENTEROLOGY & MOTILITY, Issue 12 2006
R. Mitsui
Abstract, Dietary fibre consumption is known to be beneficial to increase stool bulk and frequency. In contrast, it is unclear whether chronic dietary fibre deficiency affects colonic motor functions, especially neuronally mediated muscle contractions. In this study, rats were fed a fibre-free diet or diet containing dietary fibre (cellulose or guar gum) for 27 days. Furthermore, neurogenic and myogenic contractions were evaluated in circular and longitudinal muscle strips of the distal colon. Additionally, the number of enterochromaffin (EC) cells, which play important roles in the initiation of the peristaltic reflex, was also examined by immunohistochemistry for serotonin. Myogenic contractions induced by carbachol or substance P were examined in the presence of tetrodotoxin. Circular muscle was hyposensitive to carbachol, but longitudinal muscle was hypersensitive to substance P in the fibre-free group. Nerve-mediated circular (5,20 Hz) and longitudinal (1,2 Hz) muscle contractions evoked by electrical field stimulation were attenuated in the fibre-free group and the latter response was almost abolished by atropine, suggesting functional changes of cholinergic neurons. EC cell number was decreased in the fibre-free group. In conclusion, changes in neurogenic and myogenic contractions and a decrease in EC cell number observed may affect colonic motility of the fibre-free group. [source]

5-HT4 receptors on cholinergic nerves involved in contractility of canine and human large intestine longitudinal muscle

BRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2000
N H Prins
5-HT4 receptors mediate circular muscle relaxation in both human and canine large intestine, but this phenomenon alone can not explain the improvement in colonic motility induced by selective 5-HT4 receptor agonists in vivo. We set out to characterize 5-HT4 receptor-mediated effects in longitudinal muscle strips of canine and human large intestine. Electrical field stimulation (EFS) was applied providing submaximal isotonic contractions. L -NOARG (0.1 mM) was continuously present in the organ bath to preclude nitric oxide-induced relaxation to EFS. The selective 5-HT4 receptor agonist prucalopride (0.3 ,M) enhanced EFS-evoked contractions, that were antagonized in both preparations by the selective 5-HT4 receptor antagonist GR 113808 (0.1 ,M). The prucalopride-induced increase was present in canine ascending and descending colon, but absent in rectum. Regional differences in response to prucalopride were not observed in human ascending and sigmoid colon and rectum. Incubation with atropine (1 ,M) or tetrodotoxin (0.3 ,M) inhibited EFS-induced contractions, which were then unaffected by prucalopride (0.3 ,M) in both tissues. In the presence of methysergide (3 ,M; both tissues) and granisetron (0.3 ,M; only human tissues), 5-HT (0.3 ,M) enhanced EFS-induced contractions, an effect that was antagonized by GR 113808 (0.1 ,M). In the presence of atropine or tetrodotoxin, EFS-induced contractions were inhibited, leaving 5-HT (0.3 ,M) ineffective in both preparations. This study demonstrates for the first time that in human and canine large intestine, 5-HT4 receptors are located on cholinergic neurones, presumably mediating facilitating release of acetylcholine, resulting in enhanced longitudinal muscle contractility. This study and previous circular muscle strip studies suggest that 5-HT4 receptor agonism facilitates colonic propulsion via a coordinated combination of inhibition of circumferential resistance and enhancement of longitudinal muscle contractility. British Journal of Pharmacology (2000) 131, 927,932; doi:10.1038/sj.bjp.0703615 [source]