Origin of Motion in the Human Ureter: Mechanics, Energetics and Kinetics of the Myosin Molecular Motors

2012 ◽  
Vol 79 (2) ◽  
pp. 123-129 ◽  
Author(s):  
Romina Vargiu ◽  
Anna Perinu ◽  
Antonello De Lisa ◽  
Frank Tintrup ◽  
Francesco Manca ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Molecular Motors ◽  
Circular Muscle ◽  
Muscle Layer ◽  
Shortening Velocity ◽  
Smooth Muscle Layer ◽  
Circular Smooth Muscle ◽  
Longitudinal Smooth Muscle ◽  
Human Ureter

Background Ureteral peristalsis is the result of coordinated mechanical motor performance of longitudinal and circular smooth muscle layer of the ureter wall. The main aim of this study was to characterize in smooth muscle of proximal segments of human ureter, the mechanical properties at level of muscle tissue and at level of myosin molecular motors. Methods Ureteral samples were collected from 15 patients, who underwent nephrectomy for renal cancer. Smooth muscle strips longitudinally and circularly oriented from proximal segments of human ureter were used for the in vitro experiments. Mechanical indices including the maximum unloaded shortening velocity (Vmax), and the maximum isometric tension (P0) normalized per cross-sectional area, were determined in vitro determined in electrically evoked contractions of longitudinal and circular smooth muscle strips. Myosin cross-bridge (CB) number per mm2 (Ψ) the elementary force per single CB (Ψ) and kinetic parameters were calculated in muscle strips, using Huxley's equations adapted to nonsarcomeric muscles. Results Longitudinal smooth muscle strips exhibited a significantly (p<0.05) faster Vmax (63%) and a higher P0 (40%), if compared to circular strips. Moreover, longitudinal muscle strips showed a significantly higher unitary force (Ψ) per CB. However, no significant differences were observed in CB number, the attachment (f1) and the detachment (g2) rate constants between longitudinal and circular muscle strips. Conclusions The main result obtained in the present work documents that the mechanical, energetic and unitary forces per CB of longitudinal layer of proximal ureter are better compared to the circular one; these preliminary findings suggested, unlike intestinal smooth muscle, a major role of longitudinal smooth muscle layer in the ureter peristalsis.

Myosin phosphorylation and contraction of feline esophageal smooth muscle

1985 ◽  
Vol 249 (1) ◽  
pp. C9-C14 ◽  
Author(s):  
N. W. Weisbrodt ◽  
R. A. Murphy
Keyword(s):  
Smooth Muscle ◽  
Mechanical Activation ◽  
Smooth Muscles ◽  
Circular Muscle ◽  
Electrical Field Stimulation ◽  
Muscle Layer ◽  
Field Stimulation ◽  
Shortening Velocity ◽  
Myosin Phosphorylation ◽  
Isotonic Shortening

We tested the hypothesis that phosphorylation of the 20,000-Da light chain of myosin (LC 20) is related to mechanical activation of esophageal smooth muscle. Circular muscle layer strips of cat esophagus were taken from the lower esophageal sphincter (LES) and the distal esophageal body (EB). The LES strips developed tone spontaneously, and the EB strips were tonically contracted with carbachol. Both tissues relaxed in response to electrical-field stimulation. Phosphorylation of the LC 20 was determined in tissues quick-frozen during relaxation and during stress redevelopment after cessation of field stimulation. Stress and phosphorylation levels were low after 30 s of field stimulation, and a rapid contraction followed field stimulation. Phosphorylation in the LES increased from 0.043 +/- 0.029 to 0.328 +/- 0.043 mol Pi/mol LC 20 within 10 s after stimulation of the inhibitory nerves was terminated, while stress was still rising rapidly. Phosphorylation in the LES then declined to a steady-state value of 0.162 +/- 0.034 mol Pi/mol LC 20 after 10 min. Isotonic shortening velocities at a constant afterload following a quick release showed changes with time that were proportional to the level of phosphorylation. This was also true for values of maximal shortening velocity estimated for zero external load and for the rate of stress redevelopment after a step shortening. Comparable measurements were made in the carbachol-contracted EB. These results indicate that visceral smooth muscles, which normally function tonically (LES) or phasically (EB), exhibit an initial rapid mechanical activation associated with myosin phosphorylation.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals  Expression of corticotropin releasing factor (CRF) in the enteric nervous system of the jejunum of sheep

2011 ◽  
Vol 56 (No. 11) ◽  
pp. 551-560 ◽  
Author(s):  
A. Czujkowska ◽  
MB Arciszewski
Keyword(s):  
Nervous System ◽  
Smooth Muscle ◽  
Muscle Layer ◽  
Corticotropin Releasing Factor ◽  
Enteric Neurons ◽  
Nerve Fibres ◽  
Myenteric Neurons ◽  
Smooth Muscle Layer ◽  
Circular Smooth Muscle ◽  
A Minor

&nbsp;Corticotropin releasing factor (CRF), a 41-amino acid neuropeptide widely distributed in the mammalian central nervous system, has been shown to influence several gastrointestinal functions. Recent studies show that CRF released locally from enteric nerves may also underlie alterations in gut function. In this study, immunohistochemisty was applied to demonstrate the presence of CRF in the jejunum of sheep. Using double immunohistochemical staining the co-localization of CRF with vasoactive intestinal peptide (VIP), galanin, tyrosine hydroxylase (TH), neuropeptide&nbsp;Y (NPY) and substance P (SP) was evaluated. The presence of CRF was detected in myenteric neurons (3.6 &plusmn; 0.9%) as well as in submucous neurons (10.5 &plusmn; 1.2%). In the ovine jejunum different numbers of CRF-expressing nerve fibres were detected in myenteric ganglia, submucous ganglia, circular smooth muscle layer, lamina muscularis mucosae and between mucosal glands. None of the CRF-positive enteric neurons and CRF-positive nerve fibres exhibited the presence of TH. CRF-immunoreactive (IR) myenteric neurons widely co-expressed VIP and/or NPY. A minor population of CRF-IR myenteric neurons additionally co-stored SP. Galanin was not present in CRF-IR myenteric neurons. The presence of VIP was observed in the vast majority of CRF-positive submucous neurons. Moderate numbers of CRF-IR sumbucous neurons co-expressing galanin or NPY were also found. The presence of SP in CRF-positive submucous neurons was noted only incidentally. In the circular smooth muscle layer CRF-IR/VIP-IR, CRF-IR/NPY-IR as well as CRF-IR/SP-IR nerve fibres were present. In the mucosal layer of the ovine jejunum CRF-IR nerve fibres co-stored additionally VIP, galanin, NPY or SP. This present study provides for the first time evidence that CRF present in different subclasses of enteric neurons may influence certain activities of the ovine jejunum. Co-localization studies indicate that VIP, galanin, SP and NPY functionally co-operate with CRF in the jejunum of the sheep. &nbsp;

Biochemical and Cytochemical Characterization of Extracellular Proteoglycans in the Inner Circular Smooth Muscle Layer of Dog Small Intestine

IUBMB Life ◽  
2002 ◽  
Vol 54 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Olga Maria Szymanski de Toledo ◽  
M&#x000F4;nica Val&#x000E9;ria Marquezini ◽  
Kaio Bin Jia ◽  
M&#x000F4;nica de Campos Pinheiro ◽  
Oswaldo Alves Mora
Keyword(s):  
Smooth Muscle ◽  
Small Intestine ◽  
Muscle Layer ◽  
Smooth Muscle Layer ◽  
Circular Smooth Muscle

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.

Autoradiographical localization of oxytocin binding sites on ovine oviduct and uterus throughout the oestrous cycle

1991 ◽  
Vol 3 (2) ◽  
pp. 127 ◽  
Author(s):  
JM Wallace ◽  
R Helliwell ◽  
PJ Morgan
Keyword(s):  
Smooth Muscle ◽  
Binding Sites ◽  
Specific Binding ◽  
Muscle Layer ◽  
Oestrous Cycle ◽  
Luminal Epithelium ◽  
Binding Assays ◽  
Smooth Muscle Layer ◽  
Receptor Assays

A highly specific oxytocin receptor ligand, 125I-labelled d(CH2)5[Tyr(Me)2,Thr4,Tyr-NH9(2)] vasotocin (125I-OTA), was used to localize high affinity oxytocin receptors in ovine uterine and oviduct tissues throughout the oestrous cycle. The pattern of binding revealed by in vitro autoradiography correlated well with the results of the homogenate receptor assays using the same ligand and with previous binding assays using the tritiated ligand. At oestrus, specific 125I-OTA binding was evident on the luminal epithelium of the caruncular and intercaruncular regions, on the epithelial cells lining the secretory uterine glands and in the stroma underlying the caruncular epithelium. In the myometrium diffuse labelling was evident in the outer longitudinal smooth muscle layer. At Day 4 of the cycle, binding to the stroma was diffuse and virtually absent from the glandular epithelium. No specific binding was evident in either tissue at Day 12 of the luteal phase, but by Day 14, prior to the decrease in peripheral progesterone concentrations, binding was again apparent on the luminal epithelium only. Specific binding to the oviduct was localized to the smooth muscle layer of the isthmus region of oestrous ewes and was not detected at any other stage of the oestrous cycle. These studies extend our knowledge of the distribution of oxytocin binding sites in uterine and oviduct tissues throughout the oestrous cycle and suggest that oxytocin has an important role in stimulating oviduct and uterine motility at a time crucial to successful egg collection and/or sperm embryo transport.

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.

The longitudinal smooth muscle layer of the pig small intestine is innervated by both myenteric and submucous neurons

2002 ◽  
Vol 117 (6) ◽  
pp. 481-492 ◽  
Author(s):  
Jurgen Hens ◽  
Mariusz Gajda ◽  
Dietrich W. Scheuermann ◽  
Dirk Adriaensen ◽  
J.-P. Timmermans
Keyword(s):  
Smooth Muscle ◽  
Small Intestine ◽  
Muscle Layer ◽  
Smooth Muscle Layer ◽  
Longitudinal Smooth Muscle

Anatomic localization of cholecystokinin receptors to the pyloric sphincter

1984 ◽  
Vol 246 (1) ◽  
pp. R127-R130 ◽  
Author(s):  
G. T. Smith ◽  
T. H. Moran ◽  
J. T. Coyle ◽  
M. J. Kuhar ◽  
T. L. O'Donahue ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Muscle Layer ◽  
Pyloric Sphincter ◽  
Gastric Distension ◽  
Gi Tract ◽  
Cck Receptors ◽  
Circular Smooth Muscle ◽  
Cholecystokinin Receptors ◽  
Anatomic Localization

In an effort to identify target sites within the gastrointestinal (GI) tract through which cholecystokinin (CCK) may exert its gastric inhibitory and satiety effects, the distribution of CCK receptors was mapped in the stomach and small bowel by in vitro radiography utilizing 125I-labeled Bolton-Hunter CCK-33. Specific receptor binding was localized to the circular smooth muscle layer of the pyloric sphincter. Negligible binding was observed in the oblique, circular, or longitudinal muscle layers of other GI levels. Moderate nonspecific binding was associated with mucosal tissue in all gastric sections. The restriction of CCK receptors to the circular smooth muscle of the pyloric sphincter suggests this location as the site through which CCK inhibits gastric emptying. Gastric distension secondary to this inhibition may be the mechanism for CCK-induced satiety.

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