Gastrointestinal blood flow in the opossum with special reference to the esophagus

1990 ◽  
Vol 68 (9) ◽  
pp. 1221-1225 ◽  
Author(s):  
Folkert G. Zijlstra ◽  
Taimi T. Hynna-Liepert ◽  
P. K. Dinda ◽  
Ivan T. Beck ◽  
William G. Paterson
Keyword(s):  
Animal Model ◽  
Blood Flow ◽  
Smooth Muscle ◽  
Gastrointestinal Tract ◽  
Lower Esophageal Sphincter ◽  
Striated Muscle ◽  
Muscularis Propria ◽  
Distal Esophagus ◽  
Muscle Fibres ◽  
Esophageal Sphincter

The opossum esophagus, like that of the human, is composed of striated muscle fibres proximally and smooth muscle fibres distally. Because of this similarity the opossum has been used extensively as an animal model for esophageal studies, but to date no data on esophageal blood flow have been reported in this species. The purpose of this study was to establish the basal blood flow characteristics of different regions of the opossum gastrointestinal tract with particular reference to the esophagus. Intracardiac injection of 15-μm microspheres was used to provide an estimate of blood flow (mL∙min−1∙g−1 dry tissue) to the whole wall, the combined layer of mucosa plus submucosa, and the muscularis propria. Basal blood flow in the whole tissue and mucosa–submucosa was significantly higher in the lower esophageal sphincter than in the proximal or distal esophagus. The muscularis propria blood flow displayed an aborally increasing gradient with flow to proximal esophagus (striated muscle) < distal esophagus (smooth muscle) < lower esophageal sphincter. Regional differences in blood flow to other regions of the gastrointestinal tract were similar to that described in other species. In addition, no changes in basal blood flow occurred despite repeated microsphere injections, suggesting that this species provides a good animal model for the study of gastrointestinal blood flow.Key words: microspheres, blood flow, esophagus, stomach, intestine.

The effect of pitressin on esophageal blood flow of the dog

1991 ◽  
Vol 69 (12) ◽  
pp. 1810-1813 ◽  
Author(s):  
S. F. White ◽  
P. K. Dinda ◽  
I. T. Beck
Keyword(s):  
Blood Flow ◽  
Lower Esophageal Sphincter ◽  
Intravenous Infusion ◽  
Striated Muscle ◽  
Partial Agonist ◽  
Venous Pressure ◽  
The Body ◽  
Portal Venous Pressure ◽  
Squamous Mucosa ◽  
Esophageal Sphincter

In a previous study on canine esophagus, we reported that intravenous infusion of isoproterenol caused mucosal (i.e., mucosal + submucosal) vasodilation only in the lower esophageal sphincter (but not in the body) and muscularis vasodilation only in the body (not in the lower esophageal sphincter). In the present study, we have investigated in dogs whether these esophageal tissues also exhibit a similar difference in their vasoconstrictory response to intravenous infusion of pitressin. All measurements were made before (basal) and after infusion of 0.02 U pitressin∙min−1∙kg−1 for 15 min. Pitressin significantly decreased portal venous pressure and blood flow, and increased vascular resistance of all tissues of the esophagus. This vasoconstriction of the tissues, however, was higher in the squamous mucosa of the body than in the columnar mucosa of the lower esophageal sphincter. In contrast, it was higher in the smooth muscle of the lower esophageal sphincter than in the striated muscle of the body. These data together with those of our previous report on isoproterenol demonstrate that pitressin causes a pronounced vasoconstriction in those esophageal tissues where isoproterenol had no effect. Conversely, pitressin causes least vasoconstriction in those tissues where isoproterenol produced a significant vasodilation. These differences could be the result of partial agonist actions or differences in receptor density or in receptor-effector coupling mechanism.Key words: microspheres, portal venous pressure, esophageal body, lower esophageal sphincter.

Biomechanical and sensory parameters of the human esophagus at four levels

1998 ◽  
Vol 275 (2) ◽  
pp. G187-G191 ◽  
Author(s):  
Rig S. Patel ◽  
Satish S. C. Rao
Keyword(s):  
Smooth Muscle ◽  
Striated Muscle ◽  
Upper Esophageal Sphincter ◽  
Distal Esophagus ◽  
Cross Sectional ◽  
Impedance Planimetry ◽  
Biomechanical Parameters ◽  
Esophageal Sphincter ◽  
Four Levels ◽  
Sensory Parameters

The biomechanical and sensory characteristics of the lower esophageal sphincter (LES) and those of the striated and smooth muscle portions of the esophagus have not been compared in humans. Our aim was to determine sensory perception, cross-sectional area (CSA), and biomechanical parameters at different levels of the esophagus. We studied 11 healthy volunteers, using impedance planimetry. Intermittent balloon distensions (5–60 cmH2O) were performed at four sites: 1) the LES, 2) 5 cm above LES (distal), 3) 10 cm above LES (mid), and 4) 5 cm below the upper esophageal sphincter (proximal). During these distensions, CSAs, biomechanical parameters, and sensory responses were measured. The mid-esophagus had a higher ( P < 0.05) CSA than the distal esophagus. The LES had the smallest CSA ( P < 0.05). The LES and the proximal esophagus had greater ( P < 0.05) wall tension and were less ( P < 0.05) deformable than the mid- or distal esophagus. Sensory thresholds were lower ( P < 0.05) in the proximal compared with the mid- or distal esophagus. Biomechanical and sensory parameters are not uniform along the length of the esophagus. The striated muscle portion is more sensitive and less compliant than the smooth muscle portion. These differences could affect the results of balloon distension tests of the esophagus.

Diversity of K+ channels in circular smooth muscle of opossum lower esophageal sphincter

2001 ◽  
Vol 120 (5) ◽  
pp. A200-A200
Author(s):  
Y ZHANG ◽  
D MILLER ◽  
W PATERSON
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
K Channels ◽  
Circular Smooth Muscle ◽  
Esophageal Sphincter

Prostaglandin F2α(PGF2α)-induced contraction of human esophageal and lower esophageal sphincter circular smooth muscle

2001 ◽  
Vol 120 (5) ◽  
pp. A218-A218
Author(s):  
W CAO ◽  
K HARNETT ◽  
J BEHAR ◽  
P BIANCANI
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
Prostaglandin F2α ◽  
Circular Smooth Muscle ◽  
Esophageal Sphincter

Esophageal manometry in the opossum.

1977 ◽  
Vol 233 (3) ◽  
pp. E152
Author(s):  
K Schulze ◽  
W J Dodds ◽  
J Christensen ◽  
J D Wood
Keyword(s):  
Animal Model ◽  
Lower Esophageal Sphincter ◽  
Esophageal Manometry ◽  
Lower Esophageal Sphincter Pressure ◽  
Upper Esophageal Sphincter ◽  
Sphincter Pressure ◽  
Coronal Section ◽  
Esophageal Sphincter ◽  
Human Esophagus

The opossum esophagus is commonly used as an animal model of the human esophagus. We used esophageal manometry in normal animals to provide basal data about normal esophageal motor functions in vivo in this species. At rest, separate and distinct high pressure zones can be recorded at the level of the lower esophageal sphincter, diaphragmatic hiatus, aortic arch, and upper esophageal sphincter. Each zone demonstrates a characteristic pattern of pressures in the radii of the coronal section and a characteristic response to swallowing. The hiatal and aortic zones can be mistaken for the esophageal sphincters. Pressures in the sphincters fall with swallowing. Peristalsis is not bolus-dependent and occurs with 98% of swallows. Pressures generated by peristalsis are greater in the middle of the esophagus than at the ends. Values for resting lower esophageal sphincter pressure and the characteristics of peristalsis were reproducible between different studies in the same animals.

Thyrotropin-releasing hormone: an inhibitory regulatory peptide of feline lower esophageal sphincter

1993 ◽  
Vol 264 (3) ◽  
pp. G522-G527 ◽  
Author(s):  
H. P. Parkman ◽  
J. C. Reynolds ◽  
C. P. Ogorek ◽  
M. S. Kreider
Keyword(s):  
Gastrointestinal Tract ◽  
Substance P ◽  
Lower Esophageal Sphincter ◽  
Muscle Layer ◽  
Left Gastric Artery ◽  
Thyrotropin Releasing Hormone ◽  
Relative Distribution ◽  
Releasing Hormone ◽  
Exogenous Substance ◽  
Esophageal Sphincter

The functional role of thyrotropin-releasing hormone (TRH) at the lower esophageal sphincter (LES) was examined in the cat. The specific aims of this study were to determine: 1) the relative distribution of TRH throughout the feline gastrointestinal tract and 2) the effect of TRH on LES basal pressures and its response to exogenously induced contractions. TRH concentrations were determined by radioimmunoassay in tissue extracts from 12 sites. The mean concentration of TRH at the manometrically determined LES was 240 +/- 85 pg/g wet wt tissue, and the maximal concentration was just distal to the LES (659 +/- 189 pg/g wet wt). TRH concentration was higher in the mucosa than the underlying muscle layer of the fundus, antrum, duodenum, and ileum. In physiological studies, TRH given selectively via the left gastric artery had no effect on basal LES or esophageal pressures. TRH (2.8 x 10(-8) mol/kg) decreased the LES response to the D50 of substance P by 47.2% (34.8 +/- 3.1 to 18.4 +/- 2.9 mmHg, P < 0.01). In the presence of tetrodotoxin, TRH gave a similar inhibition of substance P-induced contractions (53.5%). TRH also decreased bombesin-induced contractions by 47.5% (29.6 +/- 6.0 to 15.8 +/- 3.9 mmHg, P < 0.025). TRH, however, had no effect on bethanechol-induced contractions. We conclude that 1) TRH is present throughout the gastrointestinal tract, with highest concentrations in the region distal to the LES; 2) TRH has no effect on basal LES tone; and 3) TRH inhibits the LES response to endogenously released and exogenous substance P but not the LES response to bethanechol.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibitory Effect of β3-Adrenoceptor Agonist in Lower Esophageal Sphincter Smooth Muscle: In Vitro Studies

2003 ◽  
Vol 304 (1) ◽  
pp. 48-55 ◽  
Author(s):  
D. N. K. Sarma ◽  
Kuldip Banwait ◽  
Ashim Basak ◽  
Anthony J. DiMarino ◽  
Satish Rattan
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
Inhibitory Effect ◽  
In Vitro Studies ◽  
Adrenoceptor Agonist ◽  
Esophageal Sphincter

scholarly journals Differences between esophageal body and lower esophageal sphincter in mitochondria of smooth muscle in opossum

1983 ◽  
Vol 85 (3) ◽  
pp. 650-656 ◽  
Author(s):  
James Christensen ◽  
Richard L. Roberts
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
Esophageal Body ◽  
Esophageal Sphincter

Nicotine stimulates esophageal peristaltic contractions in cats by a central mechanism

1992 ◽  
Vol 262 (3) ◽  
pp. G567-G571 ◽  
Author(s):  
B. Greenwood ◽  
E. Blank ◽  
W. J. Dodds
Keyword(s):  
Smooth Muscle ◽  
Striated Muscle ◽  
Upper Esophageal Sphincter ◽  
Smooth Muscle Contractility ◽  
Muscle Response ◽  
Central Brain ◽  
Site Of Action ◽  
Cervical Vagotomy ◽  
Esophageal Sphincter ◽  
Peristaltic Contractions

The aim of the present study was to 1) characterize nicotine-induced peristalsis in the feline esophagus and 2) determine the site of action of nicotine. Experiments were done on ketamine-sedated cats. Esophageal contractions were measured using a multilumen catheter assembly system. After recording 1 degree and 2 degrees peristaltic sequences nicotine (50-100 micrograms/kg iv) was administered. Nicotine induced a peristaltic contraction through the esophageal striated and smooth muscle part of the esophagus, which was not associated with any mylohyoid electromyogram activity or pharyngeal response, although the upper esophageal sphincter did relax. Addition of either atropine (20-50 micrograms/kg iv) or hexamethonium (10-20 mg/kg iv), a peripherally acting nicotinic antagonist, did not affect the striated muscle portion of the nicotine-induced esophageal contractile response but antagonized the smooth muscle response. However, mecamylamine (0.5-1 mg/kg iv), a ganglionic antagonist that crosses the blood-brain barrier, abolished the esophageal response to nicotine. Succinylcholine (0.5-1 mg/kg iv) abolished the striated muscle response without affecting the nicotine-induced smooth muscle contractility. Finally, the nicotine-induced peristaltic sequence was abolished after bilateral cervical vagotomy. In conclusion, nicotine, administered peripherally, activates central brain stem mechanisms that mediate a peristaltic sequence through the feline esophagus.

Evidence for Na+-activated K+ channels in circular smooth muscle of opossum lower esophageal sphincter

2003 ◽  
Vol 124 (4) ◽  
pp. A344
Author(s):  
Yong Zhang ◽  
Paterson G. William
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
K Channels ◽  
Circular Smooth Muscle ◽  
Esophageal Sphincter
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