Mechanical and electrical activity of esophageal smooth muscle during peristalsis

1984 ◽  
Vol 246 (2) ◽  
pp. G145-G150 ◽  
Author(s):  
D. J. Sugarbaker ◽  
S. Rattan ◽  
R. K. Goyal
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Longitudinal Muscle ◽  
Vagal Stimulation ◽  
Stimulus Frequency ◽  
Circular Muscle ◽  
Mechanical Activity ◽  
Pedicle Flap ◽  
Spike Burst ◽  
Suction Electrode

Mechanical events and membrane potential changes in response to evoked swallows and cervical vagal stimulation (10 and 40 Hz) were recorded in anesthetized opossums. Miniature strain-gauge transducers monitored the mechanical activity of the two layers. A suction electrode recorded from the intact esophagus, from a proximally based pedicle flap of longitudinal muscle (LM), and from circular muscle (CM). The onset of swallowing was marked by the onset of mylohyoid activity. During swallows LM contraction preceded CM contraction and was of longer duration. The latencies of LM and CM contraction were 1,980 +/- 38 and 2,250 +/- 101 ms, respectively. The durations of contraction of LM and CM were 5,590 +/- 260 and 3,330 +/- 67 ms, respectively. LM showed no hyperpolarization but showed depolarization and spike burst. The CM showed prompt hyperpolarization followed by depolarization and spike burst. Responses to vagal stimulation were qualitatively similar to swallows. The different components of the responses were quantitatively modified by changes in stimulus frequency. These studies show that, during peristalsis in response to swallows and vagal stimulation, 1) LM contraction occurs before CM and is of longer duration, and 2) unlike CM, LM does not hyperpolarize prior to depolarization.

Swallowing induces sequential activation of esophageal longitudinal smooth muscle

1984 ◽  
Vol 247 (5) ◽  
pp. G515-G519 ◽  
Author(s):  
D. J. Sugarbaker ◽  
S. Rattan ◽  
R. K. Goyal
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Muscle Activation ◽  
Longitudinal Muscle ◽  
Vagal Stimulation ◽  
Circular Muscle ◽  
Mechanical Activity ◽  
Circular Smooth Muscle ◽  
Muscle Contract ◽  
Sequential Activation

We examined the mechanical activity of the longitudinal and circular muscles of the esophagus at three different levels (9, 5, and 1 cm above the lower esophageal sphincter) during peristalsis induced by swallows or vagal stimulation in anesthetized opossums with miniature strain gauges applied in the axis of muscle fibers. The onset of longitudinal muscle contraction occurred in an aboral sequence with swallows but simultaneously with vagal stimulation. The speed of longitudinal muscle activation with swallows was 7.6 +/- 1.7 cm/s. Circular muscle contraction occurred in an aboral sequence with vagal stimulation and swallowing with speeds of 4.1 +/- 0.8 and 2.3 +/- 0.1 cm/s, respectively. Longitudinal muscle contracted before the circular muscle at all sites. The duration of longitudinal muscle contraction increased aborally (P less than 0.05) with swallowing or vagal stimulation. These studies show that 1) during swallowing, esophageal longitudinal and circular smooth muscle contract in a sequential fashion, 2) the longitudinal muscle sequential contraction is due to central mechanisms, whereas circular muscle sequential contraction may be due to both central and peripheral mechanisms, and 3) peripheral neuromuscular mechanisms produce regional differences in the duration of longitudinal muscle contraction.

The Morphology of the Gut of the Brown Trout (Salmo trutta)

1959 ◽  
Vol s3-100 (50) ◽  
pp. 183-198
Author(s):  
G. BURNSTOCK
Keyword(s):  
Smooth Muscle ◽  
Salmo Trutta ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Living System ◽  
Cardiac Stomach ◽  
Longitudinal Smooth Muscle ◽  
Brown Trout Salmo Trutta ◽  
Pyloric Stomach ◽  
Longitudinal Layer

1. In the trout gut a short oesophagus containing only striated circular muscles opens into a large cardiac stomach possessing inner circular and outer longitudinal smooth muscle-coats, as well as a musculsris mucosse. Ahout 45 pyloric caeca come off the intestine, which, while containing muscle-coats, does not possess a muscularis mucosae. In the rectum, the longitudinal muscle is as thick as the circular muscle-coat, hut in other regions the circular muscle is dominant, especially in the pyloric stomach where it is over 10 times as thick ss the longitudinal layer. 2. The mucosa is distinguished by the presence of a prominent layer of dense collagen, the stratum compactum, which is perforated only by nerves and blood-vessels. This layer forms a firm and relatively inextensible (approximately 10% extensibility) basis to the gut-wall. It limits the extensibility of the smooth muscle to 75% radially in the stomach and 25% radially and longitudinally in the intestine. In contrast, the stomachs of the pike and perch, which do not possess a stratum compactum, extend up so 200%. 3. A detailed description of the regional junctions and sphincters gives a basis for the interpretation of events occurring in the living system. Valves at the junction of the pneumatic duct with the oesophagus, and between the duodenum and pyloric stomach, serve to prevent the regurgitation of gas and semi-digested food respectively. A complex sphincter mechanism exists at the pylorus, and to a lesser extent at the antrum. A series of about five circular muscle-constrictors represents the anus. 4. It is suggested that the cells forming the stratum granulosum, a layer closely associated with the stratum compactum, are composed of active fibroblast cells producing collagen. 5. The rectum contains a muscular annulo-spiral septum of unknown function which protrudes into the lumen.

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.

Effect of cold temperature on membrane potential responses in opossum esophageal circular muscle

1989 ◽  
Vol 257 (4) ◽  
pp. G637-G643
Author(s):  
D. Kauvar ◽  
J. Crist ◽  
R. K. Goyal
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Circular Muscle ◽  
Electrical Field Stimulation ◽  
Cold Temperature ◽  
Resting Membrane Potential ◽  
Spike Potential ◽  
Circular Smooth Muscle ◽  
Time To Peak ◽  
Proximal Site

The effects of cold temperature on resting membrane potential (RMP) and membrane potential responses to depolarizing electrical current and intramural nerve stimulation were examined in opossum esophageal circular smooth muscle. Intracellular recordings were made in smooth muscle strips obtained from 7 to 8 cm (proximal site) and 1 to 2 cm (distal site) above the lower esophageal sphincter. RMP was not affected by changes in temperature between 34 and 22 degrees C. Cooling caused progressive inhibition of the amplitude and a slight increase in the duration of the spike potential produced by depolarizing current. Cooling did not modify the threshold for spike potential generation but decreased the spike amplitude from 34.0 +/- 0.5 mV at 34 degrees C to 14.1 +/- 2.2 mV at 22 degrees C (P less than 0.01). Electrical field stimulation with single electrical pulses (1.0 ms) produced tetrodotoxin-sensitive biphasic membrane responses consisting of initial hyperpolarization, or an inhibitory junction potential followed by depolarization that increased in amplitude as temperature was decreased from 34 to 26 degrees C and then decreased in amplitude as temperature was further decreased. At both proximal and distal sites cooling from 34 to 22 degrees C caused more than a twofold increase in the duration of hyperpolarization and time to peak depolarization. However, the increase in the absolute time of the duration of hyperpolarization and the time to peak depolarization was significantly greater at the distal than proximal esophageal site. Cooling to 16 degrees C decreased RMP and nearly abolished the biphasic membrane potential response.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Effects of some autonomic drugs on duodenal smooth muscle.

1979 ◽  
Vol 236 (1) ◽  
pp. E33
Author(s):  
S Anuras ◽  
D L Faulk ◽  
J Christensen
Keyword(s):  
Smooth Muscle ◽  
Adrenergic Receptors ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Adrenergic Agonists ◽  
Beta Adrenergic Receptors ◽  
Cholinergic Agonists ◽  
Beta Adrenergic ◽  
Alpha Adrenergic Receptors ◽  
Relative Potencies

Longitudinal muscle strips (LMS) and circular muscle strips (CMS), 2 mm wide and 1.5--2 cm long, from opossum duodenum were exposed to some autonomic agonists. The cholinergic agonists, acetylcholine, carbachol, methacholine, and bethanechol stimulated only tonic contractions in LMS and tonic followed by phasic contractions in CMS. These effects were abolished by atropine 10(-6) M. The ED50S of all cholinergic agonists for LMS were significantly lower than for CMS. Norepinephrine caused initial contraction (abolished by phenoxybenzamine, 10(-4) M), followed by relaxation (abolished by propranolol, 10(-5) M), and isopropylnorepinephrine caused relaxation (abolished by propranolol, 10(-5) M) in both layers. There were no differences in relative potencies for adrenergic agonists between the layers. Tetrodotoxin did not affect the response to adrenergic agonists. Thus, the potency of cholinergic agonists is greater in longitudinal than in circular muscle, and the layers respond differently to cholinergic agonists. The alpha-adrenergic receptors mediate contraction and beta-adrenergic receptors mediate relaxation on the duodenal smooth muscle.

scholarly journals Pathology of idiopathic megarectum and megacolon

Gut ◽  
1997 ◽  
Vol 41 (2) ◽  
pp. 252-257 ◽  
Author(s):  
J M Gattuso ◽  
M A Kamm ◽  
I C Talbot
Keyword(s):  
Smooth Muscle ◽  
Longitudinal Muscle ◽  
Periodic Acid ◽  
Circular Muscle ◽  
Muscularis Mucosae ◽  
Periodic Acid Schiff ◽  
Muscle Fibrosis ◽  
Idiopathic Megacolon ◽  
Resected Tissue ◽  
Idiopathic Megarectum

Background—The aetiology and pathology of both idiopathic megarectum and idiopathic megacolon are unknown. In particular, it is unknown whether there are abnormalities involving enteric nerves or smooth muscle.Methods—Resected tissue was examined from 24 patients who underwent surgery for idiopathic megarectum, from six patients who had tissue resected for idiopathic megacolon, and 17 control patients who had surgery for non-obstructing large bowel cancer. Qualitative and quantitative histological examination was performed after staining with haematoxylin and eosin, periodic acid Schiff (PAS), Martius scarlet blue (MSB), and phosphotungstic acid haematoxylin (PTAH). Neural and glial tissue were examined after immunostaining with S100 and PGP9.5.Results—Compared with controls, patients with idiopathic megarectum had significant thickening of their muscularis mucosae (median 78 v 33 μm, p<0.005), circular muscle (1000 v 633 μm, p<0.005), and longitudinal muscle (1083v 303 μm, p<0.005), despite rectal dilatation. This thickening was relatively greater in the longitudinal than in the circular muscle. Fibrosis of the longitudinal muscle was seen, using MSB staining, in 58%, of circular muscle in 38%, and of muscularis mucosae in 29% of patients. The relation between muscle thickening and fibrosis was variable. The density of neural tissue in the longitudinal muscle seemed to be reduced in patients with idiopathic megarectum. There was no thickening of enteric muscle or alteration in the density of innervation in patients with idiopathic megacolon.Conclusion—There is notable thickening of the enteric smooth muscle in patients with idiopathic megarectum, but the architecture of the enteric innervation seems to be intact. Functional abnormalities of the latter remain a possible cause of the smooth muscle hypertrophy.

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.

Neuromuscular mechanisms of esophageal responses at and proximal to a distending balloon

1991 ◽  
Vol 260 (1) ◽  
pp. G148-G155 ◽  
Author(s):  
W. G. Paterson
Keyword(s):  
Smooth Muscle ◽  
Pressure Fluctuations ◽  
Muscle Membrane ◽  
Cholinergic Transmission ◽  
Spike Burst ◽  
Smooth Muscle Membrane ◽  
Cervical Vagotomy ◽  
Suction Electrode ◽  
Muscarinic Cholinergic ◽  
Alpha Chloralose

To determine the neuromuscular mechanisms involved in esophageal responses at and proximal to a distending stimulus, a manometric catheter incorporating a latex balloon at its distal end was positioned in the smooth muscle esophagus of alpha-chloralose-anesthetized opossums and used to record intraluminal pressures over the balloon and at several sites proximal to the balloon. Air inflation of the balloon evoked simultaneous phasic contractions at several sites proximal to the balloon that were abolished by bilateral cervical vagotomy. With the balloon located in the midesophagus, these proximal contractions were also abolished by atropine, and simultaneous suction electrode recordings indicated that they were associated with smooth muscle membrane depolarization and spike burst without preceding hyperpolarization. With the balloon located in the distal esophagus, the evoked proximal contractions were less atropine sensitive. Phasic pressure fluctuations recorded by the balloon itself were not affected by atropine or bilateral cervical vagotomy but were increased in amplitude by tetrodotoxin. These opossum studies suggest that unlike responses below a distending balloon, which have been shown to be noncholinergic and mediated by intramural neuromuscular mechanisms, proximal contractions depend on vagal pathways and, depending on esophageal location, muscarinic-cholinergic transmission. Contractions at the level of the distending balloon appear to be myogenic in origin.

Electrotonic current spread in colonic smooth muscle

1988 ◽  
Vol 254 (5) ◽  
pp. G702-G710 ◽  
Author(s):  
J. D. Huizinga ◽  
E. Chow
Keyword(s):  
Membrane Potential ◽  
Slow Wave ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Muscle Cells ◽  
Human Colon ◽  
Membrane Properties ◽  
Electrotonic Coupling ◽  
Current Spread ◽  
Space Constant

Current-induced changes in the membrane potential (electrotonic potentials) were measured intracellularly. The electrotonic potentials were seen to decay exponentially over many cells, suggesting electrotonic current spread. The characteristics of the electrotonic current spread were used to determine passive membrane properties of both circular and longitudinal muscle cells of human and dog colon. Electrotonic current spread was first determined along the long axes of the cells. The space constant of the circular muscle of human colon was 2.14 mm and that of the longitudinal muscle was 1.63 mm. The space constants for the dog colon were similar. The value for the time constant of dog colon circular muscle was 160 ms, whereas much higher time constants, averaging between 500 and 800 ms, were recorded from dog longitudinal muscle and both human colon muscle layers. These data suggest good electrotonic coupling in all tissues studied, along the long axes of the cells. They further suggest a relatively high membrane resistance and junctional resistance in the longitudinal muscle. Electrotonic coupling along the short axes of circular muscle cells, along the long axis of the colon, was studied in the dog. The space constant was 0.43 mm, suggesting a relatively high resistance to current flow along the short axes of the cells. In addition, along the short axes of the cells from the submucosa to the myenteric plexus side (i.e., in radial direction) a gradient was observed in resting membrane potential, slow-wave amplitude, and rate of rise of the slow-wave upstroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document