Membrane currents recorded from a fragment of rabbit intestinal smooth muscle cell

1986 ◽  
Vol 251 (3) ◽  
pp. C335-C346 ◽  
Author(s):  
Y. Ohya ◽  
K. Terada ◽  
K. Kitamura ◽  
H. Kuriyama
Keyword(s):  
Smooth Muscle ◽  
Longitudinal Muscle ◽  
Outward Current ◽  
Ionic Currents ◽  
Muscle Layer ◽  
Dependent Manner ◽  
Rabbit Ileum ◽  
Longitudinal Muscle Layer ◽  
Inward Current ◽  
K Currents

Properties of ionic currents in smooth muscle membranes of the longitudinal muscle layer of the rabbit ileum were investigated using the single electrode voltage clamp method. In the present experiments, this method was applicable only to the smooth muscle ball (fragment) and not for the dispersed whole cell, because of incompleteness of the voltage clamping. A voltage step elicited a transient inward current followed by an outward current. This outward current was partly inhibited by Mn2+ or nisoldipine or by a reduction in the extracellular [Ca2+] ([Ca2+]o). Tetraethylammonium (TEA) reduced the delayed outward current in a dose-dependent manner, but 50 mM TEA did not produce a complete block of a residual current. When the pipette contained K+-free (Cs+ with TEA+) solution, the residual outward current was abolished. The inward current was elicited at -30 mV (holding potential of -60 mV) and reached the maximal value at +10 mV; the polarity was reversed at +60 mV. This inward current depended on the [Ca2+]o and was blocked by Mn2+ or nisoldipine. Ba2+ also permeated the membrane, and the inward current evoked by Ba2+ was also blocked by Mn2+ or nisoldipine. Reduction of [Na+]o in a solution containing 2.4 mM Ca2+ neither modified the current-voltage relation nor the decay of the inward current, but when [Ca2+]o was reduced to below 1 microM, Na+ permeated the membrane and was blocked by nisoldipine. In conclusion, ionic currents were recordable from the fragmented ball of the longitudinal muscle of rabbit ileum. There were at least two K+ currents as the outward current (Ca2+-dependent K+ and delayed K+ currents) and a Ca2+ current as the inward current. The property of the Ca2+ channel was similar to that observed with other preparations.

Cellular calcium regulates outward currents in rabbit intestinal smooth muscle cell

1987 ◽  
Vol 252 (4) ◽  
pp. C401-C410 ◽  
Author(s):  
Y. Ohya ◽  
K. Kitamura ◽  
H. Kuriyama
Keyword(s):  
Smooth Muscle ◽  
Outward Current ◽  
Muscle Layer ◽  
Transient Outward Current ◽  
Physiological Salt Solution ◽  
Rabbit Ileum ◽  
Longitudinal Muscle Layer ◽  
Outward Currents ◽  
Bath Application ◽  
Sustained Outward Current

The nature of transient and oscillatory outward currents (ITO and IOO) in fragmented smooth muscle cells (smooth muscle ball, SMB) from the longitudinal muscle layer of the rabbit ileum, was studied using a single electrode voltage clamp technique. With a high K+ solution containing 0.3 mM ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) in the pipette and physiological salt solution (PSS) in the bath, the Ca inward current was followed by a large transient outward current (ITO) and spontaneous oscillations of the outward current (IOO) on the sustained outward current (ISO) were elicited by a depolarizing pulse, positive to -30 mV (holding potential of -60 mV). When the internal fluid of the SMB was replaced with Cs+-tetraethylammonium+ (TEA+) solution, or when the concentration of EGTA in the pipette was increased to 4 mM, using the intracellular perfusion technique, both ITO and IOO were abolished. In Mn2+ solution both currents were also inhibited. Bath application of TEA+, procaine or A23187 completely blocked both ITO and IOO. Caffeine (0.3-1 mM) enhanced the amplitude of ITO and generations of IOO, and concentrations of caffeine over 3 mM transiently enhanced, but finally suppressed both these currents. These results suggest that the generation of ITO is closely related to the Ca2+ influx, whereas the generation of IOO may be initiated by an increment in the intracellular concentration of Ca2+, possibly released from store sites.

In vitro microelectrode study of the electrical properties of smooth muscle in equine ileum

2001 ◽  
Vol 149 (23) ◽  
pp. 707-711 ◽  
Author(s):  
N. P. H. Hudson ◽  
I. G. Mayhew ◽  
G. T. Pearson
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Longitudinal Muscle ◽  
Muscle Cells ◽  
Muscle Layer ◽  
Potential Oscillations ◽  
Longitudinal Muscle Layer ◽  
Membrane Potential Oscillations

Intracellular microelectrode recordings were made from smooth muscle cells in cross-sectional preparations of equine ileum, superfused in vitro. Membrane potential oscillations and spike potentials were recorded in all preparations, but recordings were made more readily from cells in the longitudinal muscle layer than from cells in the circular layer. The mean (se) resting membrane potential (RMP) of smooth muscle cells in the longitudinal muscle layer was -51.9 (1.2) mV, and the membrane potential oscillations in this layer had a mean amplitude of 4.8 (0.4) mV, a frequency of 9.0 (0.1) cycles per minute and a duration of 5.8 (0.2) seconds. The membrane potential oscillations were preserved in the presence of tetrodotoxin. A waxing and waning pattern of membrane potential oscillation activity was observed. Nifedipine abolished the spiking contractile activity of the smooth muscle, did not abolish the membrane potential oscillations but did alter their temporal characteristics.

Variability in the muscle composition of rat esophagus and neural pathway of lower esophageal sphincter relaxation

2011 ◽  
Vol 301 (6) ◽  
pp. G1014-G1019 ◽  
Author(s):  
Yanfen Jiang ◽  
Valmik Bhargava ◽  
Harshal A. Lal ◽  
Ravinder K. Mittal
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Vagus Nerve ◽  
Longitudinal Muscle ◽  
Muscle Layer ◽  
Axial Stretch ◽  
Longitudinal Muscle Layer ◽  
Esophageal Sphincter ◽  
Group 2 ◽  
Group 1

Several studies from our laboratory show that axial stretch of the lower esophageal sphincter (LES) in an oral direction causes neurally mediated LES relaxation. Under physiological conditions, axial stretch of the LES is caused by longitudinal muscle contraction (LMC) of the esophagus. Because longitudinal muscle is composed of skeletal muscle in mice, vagal-induced LMC and LES relaxation are both blocked by pancuronium. We conducted studies in rats (thought to have skeletal muscle esophagus) to determine if vagus nerve-mediated LES relaxation is also blocked by pancuronium. LMC-mediated axial stretch on the LES was monitored using piezoelectric crystals. LES and esophageal pressures were monitored with a 2.5-Fr solid-state pressure transducer catheter. Following bilateral cervical vagotomy, the vagus nerve was stimulated electrically. LES, along with the esophagus, was harvested after in vivo experiments and immunostained for smooth muscle (smooth muscle α-actin) and skeletal muscle (fast myosin heavy chain). Vagus nerve-stimulated LES relaxation and esophageal LMC were reduced in a dose-dependent fashion and completely abolished by pancuronium (96 μg/kg) in six rats ( group 1). On the other hand, in seven rats, LES relaxation and LMC were only blocked completely by a combination of pancuronium ( group 2) and hexamethonium. Immunostaining revealed that the longitudinal muscle layer was composed of predominantly skeletal muscle in the group 1 rats. On the other hand, the longitudinal muscle layer of group 2 rats contained a significant amount of smooth muscle ( P < 0.05). Our study shows tight coupling between axial stretch on the LES and relaxation of the LES, which suggests a cause and effect relationship between the two. We propose that the vagus nerve fibers that cause LMC induce LES relaxation through the stretch-sensitive activation of inhibitory motor neurons.

scholarly journals Rhythmic Electrical Activity in Stomach and Intestine of Toad

1980 ◽  
Vol 86 (1) ◽  
pp. 237-248
Author(s):  
ALLEN MANGEL ◽  
C. LADD PROSSER
Keyword(s):  
Smooth Muscle ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Sodium Concentration ◽  
Muscle Layer ◽  
Free Solution ◽  
Longitudinal Muscle Layer ◽  
Longitudinal Smooth Muscle ◽  
Mammalian Intestine ◽  
Periodic Changes

The intact stomach of the toad initiates rhythmic slow-spikes of 5–15 s duration and frequency of 3-5 min−1. The spontaneous electrical waves originate in the longitudinal muscle layer; isolated circular muscle is quiescent. Aboral conduction velocity is 0.12–0.9 mm s−1. Reduction of external sodium concentration from 89.5 to 15 mM produced no effect on slow spikes, although further reduction to 1.5 mM increased frequency and decreased amplitude. Slow-spikes were unaffected by ouabain or by incubation in potassium-free solution. When calcium in the medium was reduced, slow-spike amplitude and frequency decreased. Slow-spikes exhibited a change in amplitude of 16 mV per decade change in CaO2+; slow-spikes were eliminated at 10−8 M CaO2+ and by blockers of calcium conductance channels. Intact intestine of toad demonstrated slow-waves which resembled those of mammalian intestine. These were sensitive to changes in external sodium and were eliminated by 1 × 10−4M ouabain. It is suggested that rhythmic slow-spikes of longitudinal smooth muscle of amphibian stomach may result from periodic changes in Ca conductance whereas endogenous electrical waves of intestine may result from rhythmic extrusion of sodium.

Inhibitory actions of eugenol on rat isolated ileum

2002 ◽  
Vol 80 (9) ◽  
pp. 901-906 ◽  
Author(s):  
José H Leal-Cardoso ◽  
Saad Lahlou ◽  
Andrelina N Coelho-de-Souza ◽  
David N Criddle ◽  
Glória I.B Pinto Duarte ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Methyl Ester ◽  
Essential Oil ◽  
Transmembrane Potential ◽  
Longitudinal Muscle ◽  
Direct Action ◽  
Muscle Layer ◽  
Free Solution ◽  
Longitudinal Muscle Layer ◽  
Rat Ileum

The effects of eugenol (1–2000 μM) on rat isolated ileum were studied. Eugenol relaxed the basal tonus (IC50 83 μM) and the ileum precontracted with 60 mM KCl (IC50 162 μM), an action unaltered by 0.5 μM tetrodotoxin, 0.2 mM NG-nitro-L-arginine methyl ester, 0.5 mM hexamethonium, and 1 μM indomethacin. Eugenol did not alter the resting transmembrane potential (Em) of the longitudinal muscle layer under normal conditions (5.0 mM K+) or in depolarised tissues. Eugenol reversibly inhibited contractions induced by submaximal concentrations of acetylcholine (ACh) and K+ (40 mM) with IC50 values of approximately 228 and 237 μM, respectively. Eugenol blocked the component of ACh-induced contraction obtained in Ca2+-free solution (0.2 mM EGTA) or in the presence of nifedipine (1 μM). Our results suggest that eugenol induces relaxation of rat ileum by a direct action on smooth muscle via a mechanism largely independent of alterations of Em and extracellular Ca2+ influx.Key words: essential oil, eugenol, ileum, smooth muscle, antispasmodic.

Nonselective cationic currents activated by acetylcholine in swine tracheal smooth muscle cells

1999 ◽  
Vol 77 (10) ◽  
pp. 796-805 ◽  
Author(s):  
Toshikazu Yamashita ◽  
Shinichiro Kokubun
Keyword(s):  
Smooth Muscle ◽  
Pertussis Toxin ◽  
Outward Current ◽  
Tracheal Smooth Muscle ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Pipette Solution ◽  
Inward Current ◽  
Cationic Current ◽  
Nonselective Cationic Current

Membrane currents in isolated swine tracheal smooth muscle cells were investigated using a pipette solution containing BAPTA-Ca2+ buffer and Cs+ as the major cation. With a pipette solution containing 100 nM free Ca2+, acetylcholine (ACh; 1-100 µM), in a concentration-dependent manner, activated a current without inducing shortening of cells, although neither 1 mM histamine nor 1 µM leukotriene D4 activated the current (n = 7, n is the number of cells). The effect of 100 µM ACh was suppressed by pretreatment with 100 µM atropine (n = 6) or intracellular application of preactivated pertussis toxin at a concentration of 0.1 µg·mL-1 (n = 8). Genistein (0.1-100 µM), in a concentration-dependent manner, suppressed the activation of the inward current by 100 µM ACh, whereas it did not significantly suppress that of the outward current (n = 6-8). With a pipette solution containing 50 nM free Ca2+, outward current, but not inward current, was activated by 100 µM ACh (n = 10). When the pipette solution had free Ca2+ concentrations greater than 50 nM, the inward current together with the outward current was activated. The ratio between the amplitude of the inward and outward currents was significantly increased as the free Ca2+ concentration in the pipette solution increased. The steady-state activation curve of the ACh-activated current with the 50 nM free Ca2+ pipette solution was fitted by a single Boltzmann distribution (Vh = +69.8 mV, k = -11.9 mV, n = 10). The activation time constant became smaller as the membrane potential was more depolarized (164.3 ± 5.9 ms at +40 mV to 92.4 ± 6.3 ms at +120 mV, n = 10). The reversal potential was not significantly changed by reducing extracellular Cl- concentration to one-tenth of the control (n = 8), suggesting that the current is a nonselective cationic current. These results suggest that ACh activates an outward nonselective cationic current via pertussis toxin-sensitive G-protein(s) coupled with muscarinic receptors. Involvement of genistein-sensitive tyrosine kinase in the activation process of the current is unlikely.Key words: tracheal smooth muscle, nonselective cationic current, acetylcholine, Ca2+ dependency, genistein sensitivity.

scholarly journals Localization and steroid regulation of prostaglandin E2 receptor protein expression in ovine cervix

Reproduction ◽  
2006 ◽  
Vol 131 (4) ◽  
pp. 743-750 ◽  
Author(s):  
Thomas Schmitz ◽  
Brian A Levine ◽  
Peter W Nathanielsz
Keyword(s):  
Smooth Muscle ◽  
Protein Expression ◽  
Longitudinal Muscle ◽  
Muscle Layer ◽  
Cervical Dilatation ◽  
Cervical Ripening ◽  
Receptor Protein ◽  
Longitudinal Muscle Layer ◽  
Ripening Process ◽  
Ep Receptor

Although prostaglandin E2(PGE2) has been identified as a central mediator of the cervical ripening process, the mechanisms responsible for PGE2ripening are still poorly understood, partly because of the lack of information concerning the precise cellular localization and regulation of PGE2(EP) receptors in the cervix. To provide new insights into the mechanisms of cervical ripening, we used indirect immunofluorescence to localize cervical EP receptor protein expression in ovariectomized ewes and examined the effect of administration of progesterone or estradiol. EP receptors were widely distributed in cervical blood vessels, epithelium of the cervical canal, circular and longitudinal muscles, and stroma. Estradiol replacement decreased EP1and EP3receptor protein in blood vessel media (by 23 and 31% respectively,P< 0.05) and decreased EP1receptor protein expression in the longitudinal muscle layer (by 27%,P< 0.05). Stromal EP1and EP3receptor protein expression was also reduced by estradiol (by 29 and 20% respectively,P< 0.05). Progesterone replacement had no significant effect on EP receptor protein expression. The arterial changes would favor PGE2-induced vasodilatation, subsequent edema and leukocyte infiltration during the cervical ripening process whereas the muscular alterations would facilitate smooth muscle relaxation and cervical dilatation. Furthermore, estradiol provoked perinuclear localization of EP3receptor protein in the longitudinal muscle layer. This latter result suggests that cellular EP receptor localization is regulated by estradiol and that PGE2may also control smooth muscle contraction and regulate ovine cervical dilatation in an intracrine manner via EP3receptors.

Effect of reduced Na gradient on electrical activity in isolated bovine and feline ventricular myocytes

1988 ◽  
Vol 66 (2) ◽  
pp. 222-232 ◽  
Author(s):  
Magda Horackova ◽  
Andrzej Beresewicz ◽  
Gerrit Isenberg
Keyword(s):  
Electrical Activity ◽  
Ventricular Myocytes ◽  
Ionic Current ◽  
Outward Current ◽  
Free Solution ◽  
Initial Part ◽  
Inward Current ◽  
Ca Inward Current ◽  
Sudden Decrease ◽  
K Currents

We have studied changes in electrical activity resulting from abrupt alterations of the Na gradient, using ventricular myocytes isolated from feline and bovine hearts. Attempting to investigate the ionic current possibly generated by Na–Ca exchange, we studied the effects of the changes in [Na]o in the presence of 20 mM CsCl to inhibit K currents. To facilitate the effect of Cs, we also used a K-free solution and a patch electrode filled with 150 mM cesium glutamate. The application of 20 mM Nao resulted in hyperpolarization and the action potential duration was reduced. Under voltage clamp, 20 or 45 mM Nao generated an outward current at all membrane potentials investigated. The initial part (100–200 ms) of this current was only partially inhibited by 5 mM NiCl2 which is known to fully block the Ca inward current. However, the outward current generated by the reduced [Na]o was fully inhibited by 20 mM MnCl2 (which presumably inhibits Na–Ca exchange). Our observations extend the work on multicellular cardiac preparations indicating that the outward current elicited by a sudden decrease in Na gradient could be generated by Na–Ca exchange. Although the characteristics of this outward current support certain concepts of the Na–Ca exchange in cardiac muscle, we cannot at present exclude a contribution of other membrane current(s).

scholarly journals First reported case of per anal endoscopic myectomy (PAEM): A novel endoscopic technique for resection of lesions with severe fibrosis in the rectum

2017 ◽  
Vol 05 (03) ◽  
pp. E146-E150 ◽  
Author(s):  
David Rahni ◽  
Takashi Toyonaga ◽  
Yoshiko Ohara ◽  
Francesco Lombardo ◽  
Shinichi Baba ◽  
...  
Keyword(s):  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Rectal Tumor ◽  
Resection Margins ◽  
Submucosal Layer ◽  
Longitudinal Muscle Layer ◽  
Circular Muscle Layer ◽  
Tunneling Method ◽  
Severe Fibrosis

Background and study aims A 54-year-old man was diagnosed with a rectal tumor extending through the submucosal layer. The patient refused surgery and therefore endoscopic submucosal dissection (ESD) was pursued. The lesion exhibited the muscle retraction sign. After dissecting circumferentially around the fibrotic area by double tunneling method, a myotomy was performed through the internal circular muscle layer, creating a plane of dissection between the internal circular muscle layer and the external longitudinal muscle layer, and a myectomy was completed.The pathologic specimen verified T1b grade 1 sprouting adenocarcinoma with 4350 µm invasion into the submucosa with negative resection margins.

Sodium nitrite, a potent relaxant of rat stomach fundus: in vitro evidence

1998 ◽  
Vol 76 (10-11) ◽  
pp. 989-999 ◽  
Author(s):  
Michal Ceregrzyn ◽  
Tsuyoshi Ozaki ◽  
Atsukazu Kuwahara ◽  
Maria Wiechetek
Keyword(s):  
Methylene Blue ◽  
Potassium Channels ◽  
Guanylate Cyclase ◽  
Sodium Nitrite ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Rat Stomach ◽  
Longitudinal Muscle Layer ◽  
Stomach Fundus

The effects of sodium nitrite (0.1, 1, 10 mM) on mechanical activity of isolated rat stomach fundus muscle and the influence of guanylate cyclase activity inhibitor (methylene blue) and channel inhibitors (tetrodotoxin, charybdotoxin, apamin) were studied. Nitrite evoked dose-dependent relaxation in the longitudinal and circular muscle layers. The lowest effective concentration of sodium nitrite was 0.1 mM, which is comparable with the NOAEL (no observed adverse effect level). Tetrodotoxin (1 µM) markedly inhibited electrically induced contraction and rebound relaxation, but did not influence the nitrite-induced relaxation. Charybdotoxin (100 nM) decreased the relaxation evoked by 10 mM nitrite to 52.3 and 65.7% of control reaction in the circular and longitudinal muscle layer, respectively. Apamin (100 nM) did not influence the nitrite-induced relaxation. Methylene blue (10 µM) decreased relaxation induced by nitrite in the longitudinal and circular muscle layer, respectively, to 66.7 and 54.3% of the response to 1 mM nitrite alone. Relaxation induced by nitrite was decreased in the presence of L-cysteine (5 mM), and in the circular and longitudinal muscle layer reached 29.6 and 23.1%, respectively, of the response to 1 mM nitrite alone. We conclude that the relaxing effect of nitrite on gastric fundus results from its direct action on smooth muscle cells and probably the enteric nervous system is not involved in this action. The nitrite-elicited relaxation depends on activation of guanylate cyclase and high conductance Ca2+-activated potassium channels; however, activation of potassium channels might be a part of or might act in parallel with the mechanism involving the cyclic GMP system. Effects of nitrite observed in the presence of L-cysteine suggest that nitrosothiols are not responsible for nitrite-evoked activation of guanylate cyclase.Key words: nitrite, gastric motility, tetrodotoxin, methylene blue, charybdotoxin, L-cysteine.

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