scholarly journals Ranolazine inhibits voltage-gated mechanosensitive sodium channels in human colon circular smooth muscle cells

2015 ◽  
Vol 309 (6) ◽  
pp. G506-G512 ◽  
Author(s):  
Leila Neshatian ◽  
Peter R. Strege ◽  
Poong-Lyul Rhee ◽  
Robert E. Kraichely ◽  
Amelia Mazzone ◽  
...  
Keyword(s):  
Shear Stress ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Human Colon ◽  
Smooth Muscle Contractility ◽  
Western Blots ◽  
Voltage Gated ◽  
Circular Smooth Muscle

Human jejunum smooth muscle cells (SMCs) and interstitial cells of Cajal (ICCs) express the SCN5A-encoded voltage-gated, mechanosensitive sodium channel NaV1.5. NaV1.5 contributes to small bowel excitability, and NaV1.5 inhibitor ranolazine produces constipation by an unknown mechanism. We aimed to determine the presence and molecular identity of Na+ current in the human colon smooth muscle and to examine the effects of ranolazine on Na+ current, mechanosensitivity, and smooth muscle contractility. Inward currents were recorded by whole cell voltage clamp from freshly dissociated human colon SMCs at rest and with shear stress. SCN5A mRNA and NaV1.5 protein were examined by RT-PCR and Western blots, respectively. Ascending human colon strip contractility was examined in a muscle bath preparation. SCN5A mRNA and NaV1.5 protein were identified in human colon circular muscle. Freshly dissociated human colon SMCs had Na+ currents (−1.36 ± 0.36 pA/pF), shear stress increased Na+ peaks by 17.8 ± 1.8% and accelerated the time to peak activation by 0.7 ± 0.3 ms. Ranolazine (50 μM) blocked peak Na+ current by 43.2 ± 9.3% and inhibited shear sensitivity by 25.2 ± 3.2%. In human ascending colon strips, ranolazine decreased resting tension (31%), reduced the frequency of spontaneous events (68%), and decreased the response to smooth muscle electrical field stimulation (61%). In conclusion, SCN5A-encoded NaV1.5 is found in human colonic circular smooth muscle. Ranolazine blocks both peak amplitude and mechanosensitivity of Na+ current in human colon SMCs and decreases contractility of human colon muscle strips. Our data provide a likely mechanistic explanation for constipation induced by ranolazine.

β3-Adrenoceptors: relaxant function and mRNA detection in smooth muscle cells isolated from the human colon

2004 ◽  
Vol 82 (7) ◽  
pp. 515-522 ◽  
Author(s):  
Carola Severi ◽  
Ivan Tattoli ◽  
Giovanna Romano ◽  
Vito D Corleto ◽  
Gianfranco Delle Fave
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Human Colon ◽  
Cell Types ◽  
Intrinsic Activity ◽  
Dependent Manner ◽  
Taenia Coli ◽  
Circular Smooth Muscle

Functional involvement of β3-adrenoceptors in controlling human gastrointestinal motility has not been unequivocally assessed yet. The direct myogenic contribution of these receptors was examined, by in vitro functional studies and analysis of mRNA expression, on smooth muscle cells separately isolated from taenia coli and circular muscle layers of the human colon. Isoproterenol, a nonselective β-adrenoceptor agonist, relaxed, in a concentration-dependent manner, both human taenia coli and circular colonic smooth muscle cells, although displaying a higher intrinsic activity (65.3 ± 2.3 vs. 55.2 ± 1.4% maximal relaxation) and potency (pEC50: 7.41 ± 0.07 vs. 6.32 ± 0.08) were greater on taenia coli than circular cells. In the presence of the β1-antagonist CGP20712A and of the β2-antagonist ICI 118,551, a 25–30% decrease in isoproterenol intrinsic activity was observed on both cell types and on taenia coli, the nonselective β1/β2-antagonist propranolol produced a rightward shift of the isoproterenol concentration-response curve with mean estimated pKB values (8.12 ± 0.27 at 0.1 µM and 6.45 ± 0.13 at 1 µM) lower than that expected for both β1- and β2-adrenoceptors. CGP12177A and SR 58611A, two β3-adrenoceptor agonists, presented an intrinsic activity comparable to that of isoproterenol in the presence of β1- and β2-antagonists, the former being more potent on taenia coli than on circular smooth muscle cells. β3-Adrenoceptor mRNA was detected by reverse transcription PCR on both cell types. These results strongly suggest a direct functional role of β3-adrenoceptors in the human colon.Key words: adrenoceptors, β3-adrenoceptors, smooth muscle cells, taenia coli, human colon.

Role of HERG-like K+ currents in opossum esophageal circular smooth muscle

1999 ◽  
Vol 277 (6) ◽  
pp. C1284-C1290 ◽  
Author(s):  
Hamid I. Akbarali ◽  
Hemant Thatte ◽  
Xue Dao He ◽  
Wayne R. Giles ◽  
Raj K. Goyal
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Single Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Channel Blockers ◽  
Circular Smooth Muscle ◽  
Inward Currents

An inwardly rectifying K+ conductance closely resembling the human ether-a-go-go-related gene (HERG) current was identified in single smooth muscle cells of opossum esophageal circular muscle. When cells were voltage clamped at 0 mV, in isotonic K+ solution (140 mM), step hyperpolarizations to −120 mV in 10-mV increments resulted in large inward currents that activated rapidly and then declined slowly (inactivated) during the test pulse in a time- and voltage- dependent fashion. The HERG K+ channel blockers E-4031 (1 μM), cisapride (1 μM), and La3+ (100 μM) strongly inhibited these currents as did millimolar concentrations of Ba2+. Immunoflourescence staining with anti-HERG antibody in single cells resulted in punctate staining at the sarcolemma. At membrane potentials near the resting membrane potential (−50 to −70 mV), this K+ conductance did not inactivate completely. In conventional microelectrode recordings, both E-4031 and cisapride depolarized tissue strips by 10 mV and also induced phasic contractions. In combination, these results provide direct experimental evidence for expression of HERG-like K+ currents in gastrointestinal smooth muscle cells and suggest that HERG plays an important role in modulating the resting membrane potential.

Membrane potential gradient is carbon monoxide-dependent in mouse and human small intestine

2007 ◽  
Vol 293 (2) ◽  
pp. G438-G445 ◽  
Author(s):  
Lei Sha ◽  
Gianrico Farrugia ◽  
W. Scott Harmsen ◽  
Joseph H. Szurszewski
Keyword(s):  
Carbon Monoxide ◽  
Smooth Muscle ◽  
Small Intestine ◽  
Smooth Muscle Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Muscle Layer ◽  
Wild Type ◽  
Circular Smooth Muscle ◽  
Human Small Intestine

The aims of this study were to quantify the change in resting membrane potential (RMP) across the thickness of the circular muscle layer in the mouse and human small intestine and to determine whether the gradient in RMP is dependent on the endogenous production of carbon monoxide (CO). Conventional sharp glass microelectrodes were used to record the RMPs of circular smooth muscle cells at different depths in the human small intestine and in wild-type, HO2-KO, and W/WV mutant mouse small intestine. In the wild-type mouse and human intestine, the RMP of circular smooth muscle cells near the myenteric plexus was −65.3 ± 2 mV and −58.4 ± 2 mV, respectively, and −60.1 ± 2 mV and −49.1 ± 1 mV, respectively, in circular smooth muscle cells at the submucosal border. Oxyhemoglobin (20 μM), a trapping agent for CO, and chromium mesoporphyrin IX, an inhibitor of heme oxygenase, abolished the transwall gradient. The RMP gradients in mouse and human small intestine were not altered by NG-nitro-l-arginine (200 μM). No transwall RMP gradient was found in HO2-KO mice and W/WV mutant mice. TTX (1 μM) and 1H-[1,2,4-]oxadiazolo[4,3-a]quinoxalin-1-one (10 μM) had no effect on the RMP gradient. These data suggest that the gradient in RMP across the thickness of the circular muscle layer of mouse and human small intestine is CO dependent.

scholarly journals Role of PGE2 in colonic motility: PGE2 attenuates spontaneous contractions of circular smooth muscle via EP4 receptors in the rat colon

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
Shin-Ichiro Karaki ◽  
Ryo Tanaka
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Critical Role ◽  
Colonic Motility ◽  
Protein A ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Rat Colon ◽  
Colonic Tissue ◽  
Circular Smooth Muscle

AbstractColonic motor activity is important for the formation and propulsion of feces. The production of prostaglandins (PGs) in colonic tissue is considered to play a critical role in the generation and regulation of colonic motility. In this study, we investigated the inhibitory effects of PGE2 and selective agonists of four EP receptors on the spontaneous phasic contractions, called ‘giant contractions’ (GCs), of mucosa-free circular smooth muscle strips from the rat middle colon. Neural blockade with tetrodotoxin (TTX) increased the frequency and amplitude of the GCs by about twofold. However, inhibiting PG production with piroxicam reduced the GC frequency in the presence of TTX, but did not affect the GC amplitude. In the presence of both TTX and piroxicam, exogenous PGE2 and each EP receptor agonist were cumulatively added to the tissue bath. In this setting, PGE2, the EP2 agonist ONO-AE1-259, and the EP4 agonist ONO-AE1-329, but not the EP1 agonist ONO-AE-DI-004 or the EP3 agonist ONO-AE-248, concentration-dependently reduced the GC frequency and amplitude. The PGE2-induced inhibition of GC frequency and amplitude was inhibited by the EP4 antagonist ONO-AE3-208, but not by the EP1/2 antagonist AH6809. Immunohistochemistry revealed the EP2 and EP4 receptors were localized in perinuclear sites in circular smooth muscle cells. EP2 immunoreactivity was also located in GFAP-immunoreactive enteroglia, whereas EP4 immunoreactivity was also located in HU (embryonic lethal, abnormal vision [ELAV] protein; a marker of all myenteric neurons)-immunoreactive myenteric nerve cell bodies. These results suggest that the PGs produced in the colonic tissue inhibit the GC frequency and amplitude of circular muscle in the rat middle colon, and is mediated by EP4 receptors expressed in the smooth muscle cells.

Role of gap junctions in structural arrangements of interstitial cells of Cajal and canine ileal smooth muscle

1998 ◽  
Vol 274 (6) ◽  
pp. G1125-G1141 ◽  
Author(s):  
Edwin E. Daniel ◽  
Yu-Fang Wang ◽  
Francisco S. Cayabyab
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Gap Junctions ◽  
Interstitial Cells Of Cajal ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Interstitial Cells ◽  
Slow Waves ◽  
Circular Smooth Muscle ◽  
Cells Of Cajal

We examined the structural and functional basis for pacemaking by interstitial cells of Cajal (ICC) in circular smooth muscle of the canine ileum. Gap junctions were found between ICC of myenteric plexus (MyP), occasionally between MyP ICC and outer circular smooth muscle cells, between individual outer circular smooth muscle cells, between them and ICC of the deep muscular plexus (DMP), and between DMP ICC. No visible gap junctions connected MyP ICC to longitudinal muscle cells or inner circular muscle cells. Occasionally contacts occurred between the two muscle layers. No special structures were found to connect MyP and DMP ICC networks. Octanol concentration dependently reduced the amplitude and frequency of, but did not abolish, slow waves in circular muscle in isolated ileum recorded near the MyP or the DMP. Slow waves triggered from MyP ICC by a current pulse also persisted. Contractile activity was abolished, cells were depolarized, and fast inhibitory junction potentials were reduced by octanol. We conclude that ICC pacemakers of the MyP and DMP utilize gap junctional conductances for pacemaking function but may not require them. Coupling between the two ICC networks may utilize the circular muscle syncytium.

Functional and molecular evidence of B3-adrenoceptors in smooth muscle cells isolated from the longitudinal and circular muscle layers of human colon

2000 ◽  
Vol 118 (4) ◽  
pp. A309
Author(s):  
Carola Severi ◽  
Giovanna Romano ◽  
Vito D. Corleto ◽  
Tiziano Croci ◽  
Gianfranco Delle Fave
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Human Colon ◽  
Molecular Evidence

Intercellular metabolic coupling in canine colon musculature

1995 ◽  
Vol 268 (6) ◽  
pp. C1492-C1502 ◽  
Author(s):  
L. Farraway ◽  
A. K. Ball ◽  
J. D. Huizinga
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Gap Junctions ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Muscle Layer ◽  
Circular Smooth Muscle ◽  
Metabolic Coupling ◽  
Cells Of Cajal

Intercellular communication within the musculature of the canine colon was studied by examining the results of neurobiotin diffusion after injection of the tracer into smooth muscle cells at different locations within the muscle layer. Circular muscle at the submucosal surface, circular muscle adjacent to the myenteric plexus, and longitudinal muscle demonstrated different degrees of time-dependent tracer spread. At the submucosal surface, tracer spread was rapid, extensive, and unimpeded by connective tissue septa. At the myenteric side, tracer spread was also extensive but was much slower and confined to bundles of cells bordered by septa. In contrast to previous studies that suggest an absence of gap junctions at the myenteric side of the circular muscle, the neurobiotin spread indicates full metabolic coupling of all circular smooth muscle cells. Furthermore, in contrast to the belief that longitudinal muscle is completely devoid of gap junctions, tracer spread occurred between cells in this layer, although neurobiotin diffusion was very limited, nonuniform, and slow. In each area of the musculature studied, tracer spread was inhibited by octanol. When very long injection and wait times were implemented at the submucosal surface of the circular muscle, neurobiotin was observed to cross septa through the network of interstitial cells of Cajal, indicating that it is this network that provides communication between lamellae.

Interstitial cells in deep muscular plexus of canine small intestine may be specialized smooth muscle cells

1993 ◽  
Vol 265 (4) ◽  
pp. G638-G645 ◽  
Author(s):  
S. Torihashi ◽  
S. Kobayashi ◽  
W. T. Gerthoffer ◽  
K. M. Sanders
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Smooth Muscle Actin ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Interstitial Cells ◽  
Nerve Fibers ◽  
Muscle Actin ◽  
Circular Smooth Muscle ◽  
Thick Filaments

The fine structures and properties of cells between the inner and outer circular muscle layers in the canine small intestine were studied by transmission electron microscopy (TEM), immunocytochemistry, and scanning electron microscopy (SEM). A nerve plexus (deep muscular plexus) supported by enteroglial cells, fibroblasts around blood vessels, macrophages, and thin and branched cells previously identified as interstitial cells of Cajal was observed. The interstitial cells of the deep muscular plexus (IC-DMP) were rich in mitochondria, dense bodies, and caveolae, and they were closely associated with nerve fibers. The IC-DMP had incomplete basal laminae. These cells also had numerous interconnecting gap junctions, and they also formed gap junctions with the surrounding smooth muscle cells of the outer circular muscle layer. IC-DMP were rich in myofilaments, which were primarily actin thin filaments, but myosin thick filaments, identified with anti-myosin light-chain antibodies, were also apparent. IC-DMP and circular smooth muscle cells both expressed immunoreactivity to anti-smooth muscle actin antisera, but these two types of cells differed in their intermediate filament proteins: IC-DMP featured vimentin immunopositive filaments, and circular smooth muscle cells featured desmin immunoreactivity. SEM showed that IC-DMP had thin and flat cell bodies with numerous branching processes. These cells came into close contact with nerve fibers and circular smooth muscle cells. The findings that IC-DMP cells contained myosin thick filaments and were immunopositive for anti-smooth muscle actin suggest that they may be more properly categorized as a type of smooth muscle cell.

Sign in / Sign up

Export Citation Format

Share Document