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Modzelewska B, Drygalski K, Kleszczewski T, Chomentowski A, Koryciński K, Kiełczewska A, Pawłuszewicz P, Razak Hady H. Quercetin relaxes human gastric smooth muscles directly through ATP-sensitive potassium channels and not depending on the nitric oxide pathway. Neurogastroenterol Motil 2021; 33:e14093. [PMID: 33528064 PMCID: PMC8365708 DOI: 10.1111/nmo.14093] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 01/04/2021] [Accepted: 01/12/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND Quercetin has recently become a remarkably popular subject of research due to its broad beneficial pharmacological properties. The goal of our study was to observe its effects on contractility of human gastric smooth muscles in reference to the NO pathway and direct influence of potassium channels. METHODS Tissues were obtained from patients undergoing sleeve gastrectomy due to morbid obesity (n = 10 aged 24-56; BMI 47.16 ± 1.84). The following parameters were evaluated in the recordings: area under the curve (AUC), average baseline muscle tone, and relative change in muscle contraction. KEY RESULTS Quercetin induced noticeable, dose-dependent relaxation of the carbachol treated gastric strips. The substantial effect was noted at concentrations higher than 10-7 mol/L and maximal at 10-4 mol/L (81.82 ± 3.32%; n = 10; p < 0.0001) of the control. Neither NOS blockers nor guanylyl cyclase blockers had inhibitory effects on the relaxation of strips induced by examined polyphenol. Glibenclamide inhibited the relaxing effect of quercetin, significant at concentrations higher than 5⋅10-5 mol/L. Preincubation with charybdotoxin or apamin extended the relaxing effect of quercetin (from 10-6 mol/L). Tamoxifen, in turn, significantly increased muscle relaxation at all quercetin concentrations. CONCLUSIONS & INFERENCES In conclusion, the current study was the first to show that quercetin-induced relaxation of human gastric smooth muscle occurs directly through K+ATP channels and independently to NO pathways. The present results suggest that quercetin is a potential nutraceutical in the treatment of functional gastrointestinal dyspepsia and other minor gastric muscle motility disturbance.
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Affiliation(s)
- Beata Modzelewska
- Department of BiophysicsMedical University of BiałystokBiałystokPoland
| | | | | | | | | | | | - Patrycja Pawłuszewicz
- Clinical Department of General and Endocrine SurgeryMedical University of BiałystokBiałystokPoland
| | - Hady Razak Hady
- Clinical Department of General and Endocrine SurgeryMedical University of BiałystokBiałystokPoland
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Min YW, Ko EJ, Lee JY, Rhee PL. Impaired neural pathway in gastric muscles of patients with diabetes. Sci Rep 2018; 8:7101. [PMID: 29739973 PMCID: PMC5940896 DOI: 10.1038/s41598-018-24147-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/22/2018] [Indexed: 12/22/2022] Open
Abstract
To explore the pathogenic mechanism of diabetic gastropathy, we investigated differences in response to electrical field stimulation (EFS) of gastric muscles from diabetic and non-diabetic (control) patients. Gastric specimens were obtained from 34 patients and 45 controls who underwent gastrectomy for early gastric cancer. Using organ bath techniques, we examined peak and nadir values of contraction under EFS. To examine responses to purinergic and nitrergic inhibition without cholinergic innervation, atropine, MRS2500, and N-nitro-L-arginine (L-NNA) were added sequentially to the organ bath. Tetrodotoxin (TTX) was used to confirm that the responses to EFS were mediated via neural stimulation. In the absence of pharmacological agents, peak contraction amplitude was greater in non-diabetic controls compared to diabetics only in the distal longitudinal gastric muscles. However, the nadir was greater in controls than in patients in both proximal and distal gastric circular muscles. Addition of MRS2500 could not decrease the nadir in both controls and patients, both in the proximal and distal stomach. However, L-NNA completely reversed the relaxation. TTX had no further effect on nadir. In conclusion, impaired inhibitory nitrergic neural pathway in both proximal and distal stomach and impaired excitatory cholinergic neural pathway in the distal stomach may contribute to the pathogenic mechanism underlying diabetic gastropathy.
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Affiliation(s)
- Yang Won Min
- Department of Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Eun-Ju Ko
- Biomedical Research Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji-Yeon Lee
- Biomedical Research Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Poong-Lyul Rhee
- Department of Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.
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KV7 channels in the human detrusor: channel modulator effects and gene and protein expression. Naunyn Schmiedebergs Arch Pharmacol 2016; 390:127-137. [DOI: 10.1007/s00210-016-1312-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/11/2016] [Indexed: 12/13/2022]
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Min YW, Hong YS, Ko EJ, Lee JY, Ahn KD, Bae JM, Rhee PL. Nitrergic Pathway Is the Main Contributing Mechanism in the Human Gastric Fundus Relaxation: An In Vitro Study. PLoS One 2016; 11:e0162146. [PMID: 27589594 PMCID: PMC5010257 DOI: 10.1371/journal.pone.0162146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 08/17/2016] [Indexed: 12/11/2022] Open
Abstract
Background Human gastric fundus relaxation is mediated by intrinsic inhibitory pathway. We investigated the roles of nitrergic and purinergic pathways, two known inhibitory factors in gastric motility, on spontaneous and nerve-evoked contractions in human gastric fundus muscles. Methods Gastric fundus muscle strips (12 circular and 13 longitudinal) were obtained from patients without previous gastrointestinal motility disorder who underwent gastrectomy for stomach cancer. Using these specimens, we examined basal tone, peak, amplitude, and frequency of spontaneous contractions, and peak and nadir values under electrical field stimulation (EFS, 150 V, 0.3 ms, 10 Hz, 20 s). To examine responses to purinergic and nitrergic inhibition without cholinergic innervation, atropine (muscarinic antagonist, 1 μM), MRS2500 (a purinergic P2Y1 receptor antagonist, 1 μM), and N-nitro-L-arginine (L-NNA, a nitric oxide synthase inhibitor, 100 μM) were added sequentially for spontaneous and electrically-stimulated contractions. Tetrodotoxin was used to confirm any neuronal involvement. Results In spontaneous contraction, L-NNA increased basal tone and peak in both muscle layers, while amplitude and frequency were unaffected. EFS (up to 10 Hz) uniformly induced initial contraction and subsequent relaxation in a frequency-dependent manner. Atropine abolished initial on-contraction and induced only relaxation during EFS. While MRS2500 showed no additional influence, L-NNA reversed relaxation (p = 0.012 in circular muscle, and p = 0.006 in longitudinal muscle). Tetrodotoxin abolished any EFS-induced motor response. Conclusions The relaxation of human gastric fundus muscle is reduced by nitrergic inhibition. Hence, nitrergic pathway appears to be the main mechanism for the human gastric fundus relaxation.
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Affiliation(s)
- Yang Won Min
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Yun Soo Hong
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Eun-Ju Ko
- Biomedical Research Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ji-Yeon Lee
- Biomedical Research Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ki Duck Ahn
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Je Moon Bae
- Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Poong-Lyul Rhee
- Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
- * E-mail:
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Currò D. The Modulation of Potassium Channels in the Smooth Muscle as a Therapeutic Strategy for Disorders of the Gastrointestinal Tract. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 104:263-305. [PMID: 27038377 DOI: 10.1016/bs.apcsb.2015.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Alterations of smooth muscle contractility contribute to the pathophysiology of important functional gastrointestinal disorders (FGIDs) such as functional dyspepsia and irritable bowel syndrome. Consequently, drugs that decrease smooth muscle contractility are effective treatments for these diseases. Smooth muscle contraction is mainly triggered by Ca(2+) influx through voltage-dependent channels located in the plasma membrane. Thus, the modulation of the membrane potential results in the regulation of Ca(2+) influx and cytosolic levels. K(+) channels play fundamental roles in these processes. The open probability of K(+) channels increases in response to various stimuli, including membrane depolarization (voltage-gated K(+) [K(V)] channels) and the increase in cytosolic Ca(2+) levels (Ca(2+)-dependent K(+) [K(Ca)] channels). K(+) channel activation is mostly associated with outward K(+) currents that hyperpolarize the membrane and reduce cell excitability and contractility. In addition, some K(+) channels are open at the resting membrane potential values of the smooth muscle cells in some gut segments and contribute to set the resting membrane potential itself. The closure of these channels induces membrane depolarization and smooth muscle contraction. K(V)1.2, 1.5, 2.2, 4.3, 7.4 and 11.1, K(Ca)1.1 and 2.3, and inwardly rectifying type 6K(+) (K(ir)6) channels play the most important functional roles in the gastrointestinal smooth muscle. Activators of all these channels may theoretically relax the gastrointestinal smooth muscle and could therefore be promising new therapeutic options for FGID. The challenge of future drug research and development in this area will be to synthesize molecules selective for the channel assemblies expressed in the gastrointestinal smooth muscle.
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Affiliation(s)
- Diego Currò
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, Rome, Italy.
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Currò D. K+ channels as potential targets for the treatment of gastrointestinal motor disorders. Eur J Pharmacol 2014; 733:97-101. [PMID: 24726846 DOI: 10.1016/j.ejphar.2014.03.049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/14/2014] [Accepted: 03/27/2014] [Indexed: 12/21/2022]
Abstract
K(+) channels play important functional roles in excitable cells, as neurons and muscle cells. The activation or inhibition of K(+) channels hyperpolarizes or depolarizes the cell membrane, respectively. These effects determine in the smooth muscle decrease or increase in Ca(2+) influx through voltage-gated Ca(2+) (CaV1.2) channels and relaxation or contraction, respectively. Recent studies highlight the importance of voltage-dependent type 7 K(+) (KV7 or KCNQ) channels in regulating muscle tone and contractility in stomach and colon. KV7 channels, that include 5 subtypes (KV7.1-7.5), are activated at relatively negative potential values, close to those of the resting membrane potential for the smooth muscle cells of some segments of the gastrointestinal tract. Thus, they contribute to set the resting membrane potential and their blockade induces increase in smooth muscle contractility in stomach and colon. In addition, KV7 channel activation produces profound relaxations of gastric and colonic smooth muscle. Therefore, KV7 channel activators could be used to relax the smooth muscle and relieve symptoms in diseases such as functional dyspepsia and irritable bowel syndrome with prevalent diarrhea. The discovery of activators selective for the channel subtypes present in the smooth muscle, mainly KV7.4 and 7.5, would allow avoiding adverse cardiac and nervous system effects. A further step forward would be characterizing putative differences among the KV7 channel subtypes expressed in the various smooth muscles and synthesizing molecules specific for the gastrointestinal smooth muscle.
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Affiliation(s)
- Diego Currò
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy.
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Ipavec V, Martire M, Barrese V, Taglialatela M, Currò D. KV7 channels regulate muscle tone and nonadrenergic noncholinergic relaxation of the rat gastric fundus. Pharmacol Res 2011; 64:397-409. [PMID: 21740972 PMCID: PMC3178758 DOI: 10.1016/j.phrs.2011.06.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 06/14/2011] [Accepted: 06/21/2011] [Indexed: 12/30/2022]
Abstract
Voltage-dependent type 7 K+ (KV7) channels play important physiological roles in neurons and muscle cells. The aims of the present study were to investigate the motor effects of KV7 channel modulators in the rat gastric fundus and the expression of KV7 channels in this tissue. Muscle tone and electrical field stimulation (EFS)-evoked relaxations of precontracted longitudinal muscle strips of the rat gastric fundus were investigated under nonadrenergic noncholinergic conditions by organ bath studies. Gene expression was studied by real-time PCR and tissue localization of channels was investigated by immunohistochemistry. The KV7 channel blocker XE-991 induced concentration-dependent contractions, with mean pD2 and Emax of 5.4 and 48% of the maximal U46619-induced contraction, respectively. The KV7 channel activators retigabine and flupirtine concentration-dependently relaxed U46619-precontracted strips, with pD2s of 4.7 and 4.4 and Emax of 93% and 91% of the maximal relaxation induced by papaverine, respectively. XE-991 concentration-dependently inhibited retigabine-induced relaxation with a pIC50 of 6.2. XE-991 and DMP-543, another KV7 channel blocker, increased by 13-25% or reduced by 11-21% the relaxations evoked by low- or high-frequency EFS, respectively. XE-991 also reduced the relaxation induced by vasoactive intestinal polypeptide (VIP) by 33% of controls. Transcripts encoded by all KV7 genes were detected in the fundus, with 7.4 and 7.5 showing the highest expression levels. KV7.4 and 7.5 channels were visualized by confocal immunofluorescence in both circular and longitudinal muscle layers. In conclusion, in the rat proximal stomach, KV7 channels appear to contribute to the resting muscle tone and to VIP- and high-frequency EFS-induced relaxation. KV7 channel activators could be useful relaxant agents of the gastric smooth muscle.
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Affiliation(s)
- V Ipavec
- Institute of Pharmacology, School of Medicine, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy
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Currò D. Voltage-gated calcium channels involved in the inhibitory motor responses and vasoactive intestinal polypeptide release in the rat gastric fundus. Eur J Pharmacol 2010; 628:207-13. [DOI: 10.1016/j.ejphar.2009.11.044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2009] [Revised: 10/16/2009] [Accepted: 11/03/2009] [Indexed: 12/20/2022]
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Dhaese I, Lefebvre RA. Myosin light chain phosphatase activation is involved in the hydrogen sulfide-induced relaxation in mouse gastric fundus. Eur J Pharmacol 2009; 606:180-6. [PMID: 19374871 DOI: 10.1016/j.ejphar.2009.01.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 11/24/2008] [Accepted: 01/09/2009] [Indexed: 01/09/2023]
Abstract
The relaxant effect of hydrogen sulfide (H(2)S) in the vascular tree is well established but its influence and mechanism of action in gastrointestinal smooth muscle was hardly investigated. The influence of H(2)S on contractility in mouse gastric fundus was therefore examined. Sodium hydrogen sulfide (NaHS; H(2)S donor) was administered to prostaglandin F(2alpha) (PGF(2alpha))-contracted circular muscle strips of mouse gastric fundus, before and after incubation with interfering drugs. NaHS caused a concentration-dependent relaxation of the pre-contracted mouse gastric fundus strips. The K(+) channels blockers glibenclamide, apamin, charybdotoxin, 4-aminopyridin and barium chloride had no influence on the NaHS-induced relaxation. The relaxation by NaHS was also not influenced by L-NAME, ODQ and SQ 22536, inhibitors of the cGMP and cAMP pathway, by nerve blockers capsazepine, omega-conotoxin and tetrodotoxin or by several channel and receptor blockers (ouabain, nifedipine, 2-aminoethyl diphenylborinate, ryanodine and thapsigargin). The myosin light chain phosphatase (MLCP) inhibitor calyculin-A reduced the NaHS-induced relaxation, but the Rho-kinase inhibitor Y-27632 had no influence. We show that NaHS is able to relax PGF(2alpha)-contracted mouse gastric fundus strips. The results suggest that in the mouse gastric fundus, H(2)S causes relaxation at least partially via activation of MLCP.
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Affiliation(s)
- Ingeborg Dhaese
- Heymans Institute of Pharmacology, Ghent University, Ghent, Belgium
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Hagi K, Azuma YT, Nakajima H, Shintani N, Hashimoto H, Baba A, Takeuchi T. Involvements of PHI-nitric oxide and PACAP-BK channel in the sustained relaxation of mouse gastric fundus. Eur J Pharmacol 2008; 590:80-6. [PMID: 18602629 DOI: 10.1016/j.ejphar.2008.05.045] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 05/01/2008] [Accepted: 05/20/2008] [Indexed: 12/16/2022]
Abstract
The roles of nitric oxide (NO) and K(+) channels in sustained relaxation induced by electrical field stimulation (EFS) in the presence of atropine and guanethidine were studied in circular muscle strips of mouse gastric fundus. In the wild-type mouse, N(G)-nitro-l-arginine (l-nitroarginine), a nitric oxide synthase inhibitor, significantly inhibited the sustained relaxation in addition to the rapid relaxation. The sustained relaxation in pituitary adenylate cyclase-activating peptide (PACAP)-knockout mouse, which was smaller than that of the wild-type mouse, was also inhibited by l-nitroarginine. l-Nitroarginine inhibited the relaxation induced by the peptide histidine isoleucine (PHI), but not that induced by PACAP. S-Nitroso-N-acetyl-dl-penicillamine (SNAP), a NO donor, -induced relaxation was not affected by PACAP(6-38). EFS-induced sustained relaxation was inhibited by iberiotoxin, a big conductance calcium-activated K(+) (BK) channel inhibitor, but not by apamin, a small conductance calcium-activated K(+) (SK) channel inhibitor, and glibenclamide, an ATP-sensitive K(+) channel inhibitor. The relaxation that remained after the iberiotoxin-treatment was significantly inhibited by l-nitroarginine. Iberiotoxin inhibited PACAP-induced relaxation, while it had no effect on both PHI- and SNAP-induced relaxation. Immunoreactivities to anti-BK channel and anti-PHI antibodies were found in the circular muscle and the myenteric plexus layers, respectively. These results suggest interplay between PHI and NO in the sustained relaxation of the mouse gastric fundus, and that BK channels are involved in the PACAP-component of the sustained relaxation.
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Affiliation(s)
- Kiyomi Hagi
- Laboratory of Veterinary Pharmacology, Graduate School of Life and Environmental Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai 599-8531, Japan
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Vetri T, Bonvissuto F, Marino A, Postorino A. Nitrergic and purinergic interplay in inhibitory transmission in rat gastric fundus. ACTA ACUST UNITED AC 2007; 27:151-7. [PMID: 17584445 DOI: 10.1111/j.1474-8673.2007.00406.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1 This study was undertaken to analyse the involvement of ATP in non-adrenergic non- cholinergic (NANC) relaxation and possible interplay between nitrergic and purinergic systems in rat gastric fundus. 2 Experiments were performed in vitro on strips of longitudinal muscle from rat gastric fundus, recording the mechanical activity as changes in isometric force. In addition, NO release induced by different experimental conditions was assayed. 3 Under NANC conditions in serotonin-precontracted strips, electrical field stimulation (EFS) elicited a tetrodotoxin (TTX)-sensitive relaxation accompanied by nitric oxide (NO) release. This effect was antagonized by pretreatment with the NO synthase antagonist Nomega-nitro-L-arginine (L-NA) or by desensitization of purinergic receptors. Purinergic desensitization was also able to further antagonize the residual EFS-induced relaxation remaining after L-NA treatment. Exogenously applied NO [delivered as sodium nitroprusside (SNP)] or ATP (and related purines) induced concentration-dependent, TTX-insensitive relaxant responses. ATP also induced the release of NO. A reduction in the responses to ATP was observed in the presence of L-NA. In contrast, SNP-induced relaxation remained unchanged after desensitization of purinergic receptors. Finally, apamin, a blocker of the small conductance Ca2+ -dependent K+ channels, reduced the amplitude of the muscular relaxation evoked by either EFS, ATP or SNP. 4 In conclusion, this study provides evidence that in rat gastric fundus, ATP is one of the inhibitory transmitters released from NANC intramural neurones acting directly on the muscle, through receptors coupled to apamin-sensitive Ca2+ -dependent K+ channels and, indirectly, through the stimulation of NO production.
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Affiliation(s)
- T Vetri
- Dipartimento di Biologia cellulare e dello Sviluppo, Laboratorio di Fisiologia Generale, Università degli Studi di Palermo, Viale delle Scienze, Parco D'Orleans II, Palermo, Italy
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Dixit D, Zarate N, Liu LWC, Boreham DR, Huizinga JD. Interstitial cells of Cajal and adaptive relaxation in the mouse stomach. Am J Physiol Gastrointest Liver Physiol 2006; 291:G1129-36. [PMID: 16891301 DOI: 10.1152/ajpgi.00518.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Interstitial cells of Cajal (ICC) are proposed to play a role in stretch activation of nerves and are under intense investigation for potential roles in enteric innervation. Most data to support such roles come from in vitro studies with muscle strips whereas data at the whole organ level are scarce. To obtain insight into the role of ICC in distention-induced motor patterns developing at the organ level, we studied distension-induced adaptive relaxation in the isolated whole stomach of wild-type and W/W(v) mice. A method was developed to assess gastric adaptive relaxation that gave quantitative information on rates of pressure development and maximal adaptive relaxation. Pressure development was monitored throughout infusion of 1 ml of solution over a 10-min period. The final intraluminal pressure was sensitive to blockade of nitric oxide synthase, in wild-type and W/W(v) mice to a similar extent, indicating NO-mediated relaxation in W/W(v) mice. Adaptive relaxation occurred between 0.2 and 0.5 ml of solution infusion; this reflex was abolished by TTX, was not sensitive to blockade of nitric oxide synthase, but was abolished by apamin, suggesting that ATP and not nitric oxide is the neurotransmitter responsible for this intrinsic reflex. Despite the absence of intramuscular ICC (ICC-IM), normal gastric adaptive relaxation occurred in the W/W(v) stomach. Because pressure development was significantly lower in W/W(v) mice compared with wild type in all the conditions studied, including in the presence of TTX, ICC-IM may play a role in development of myogenic tone. In conclusion, a mouse model was developed to assess the intrinsic component of gastric accommodation. This showed that ICC-IM are not essential for activation of intrinsic sensory nerves nor ATP-driven adaptive relaxation nor NO-mediated relaxation in the present model. ICC-IM may be involved in regulation of (distention-induced) myogenic tone.
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Affiliation(s)
- Devika Dixit
- Intestinal Disease Research Program, Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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Huizinga JD, Dixit D, Zarate N. Intrinsic inhibitory innervation of the stomach. Br J Pharmacol 2005; 146:163-4; author reply 164. [PMID: 15951826 PMCID: PMC1576244 DOI: 10.1038/sj.bjp.0706294] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Jan D Huizinga
- Department of Medicine, Intestinal Disease Research Program, McMaster University Hamilton, Canada
- Author for correspondence:
| | - Devika Dixit
- Department of Medicine, Intestinal Disease Research Program, McMaster University Hamilton, Canada
| | - Natalia Zarate
- Department of Medicine, Intestinal Disease Research Program, McMaster University Hamilton, Canada
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Toyoshima M, Takeuchi T, Goto H, Mukai K, Shintani N, Hashimoto H, Baba A, Hata F. Roles of PACAP and PHI as inhibitory neurotransmitters in the circular muscle of mouse antrum. Pflugers Arch 2005; 451:559-68. [PMID: 16292577 DOI: 10.1007/s00424-005-1491-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Accepted: 07/04/2005] [Indexed: 11/24/2022]
Abstract
Mediators of neurogenic responses of the gastric antrum were studied in wild-type and pituitary adenylate cyclase-activating polypeptide (PACAP) -knockout (KO) mice. Electrical field stimulation (EFS) to the circular muscle strips of the wild-type mouse antrum induced a triphasic response; rapid transient relaxation and contraction, and sustained relaxation that was prolonged for an extended period after the end of EFS. The transient relaxation and contraction were completely inhibited by L-nitroarginine and atropine, respectively. The sustained relaxation was significantly inhibited by a PACAP receptor antagonist, PACAP(6-38). The antral strips prepared from PACAP-KO mice unexpectedly exhibited a tri-phasic response. However, the sustained relaxation was decreased to about one-half of that observed in wild-type mice. PACAP(6-38) inhibited EFS-induced sustained relaxation (33.5% of control) in PACAP-KO mice. Anti-peptide histidine isoleucine (PHI) serum partially (the 30% inhibition) or significantly (the 60% inhibition) inhibited the sustained relaxations in the wild-type and PACAP-KO mice, respectively. The immunoreactivities to the anti-PACAP and anti-PHI serums were found in myenteric ganglia of the mouse antrum. These results suggest that nitric oxide and acetylcholine mediate the transient relaxation and contraction, respectively, and that PACAP and PHI separately mediate the sustained relaxation in the antrum of the mouse stomach.
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Affiliation(s)
- Makiko Toyoshima
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Science, Osaka Prefecture University, Sakai, Japan
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