Calcium dependence of neurotensin stimulation of circular colonic muscle of the rabbit

Snape, William J.; Hyman, Paul E.; Mayer, Emeran A.; Sevy, N.; Kao, H. W.; Root, D T

doi:10.1016/0016-5085(87)90446-x

Cited by 10 publications

(4 citation statements)

References 28 publications

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“…Previous studies established that extracellular calcium influx was required for contraction of colonic smooth muscle stimulated by bethanechol, neurotensin, or membrane depolarization with increasing concentrations of extracellular potassium (2). In the present study, nitrendipine inhibited in dose-dependent fashion the contraction stimulated by receptoroperated (bethanechol) and voltage-dependent (increased extracellular potassium) mechanisms.…”

Section: Discussionsupporting

confidence: 69%

“…The distal colon stores and eliminates feces. Previous studies showed that muscle strips from the distal colon had a greater maximal contraction, but no difference in potency, following stimulation with acetylcholine or neurotensin (1,2). These results suggested that receptor binding affinities are similar in proximal and distal colon, and that the observed differences in function may be a result of postreceptor events.…”

Section: Introductionmentioning

confidence: 73%

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[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

Hyman¹,

Hsu²,

Jing³

et al. 1990

Neurogastroenterology Motil

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We used [3H] nitrendipine binding to isolated smooth muscle cells and isometric tension studies of muscle strips to characterize the calcium channels from rabbit proximal and distal colon. At 25°C [3H] nitrendipine binding was rapid, saturable, reversible, specific, and linearly proportional to cell number. The affinity of the ligand for its receptor was similar in proximal and distal colon (KD 129 ± 21 pM and 124 ± 17 pM, respectively). In the proximal colon there were 68,000 receptors per cell, compared to 58,000 receptors per cell in the distal colon (p > .1). The Hill coefficient for nitrendipine was close to unity, suggesting binding to a single receptor. Although nitrendipine and nifedipine competitively inhibited [3H]nitrendipine binding, verapamil did not alter [3H] nitrendipine binding, suggesting the presence of at least two discrete, noninteracting sites for the binding of drugs that block calcium channels. In studies with muscle strips nitrendipine competitively inhibited isometric tension stimulated by both bethanechol and high extracellular potassium concentration. There were no significant differences in response from proximal and distal colon. These results suggest that calcium antagonist binding characteristics to calcium channels are similar in proximal and distal colon, and do not explain previously observed differences in the function of muscle in these tissues.

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Section: Discussionsupporting

confidence: 69%

Section: Introductionmentioning

confidence: 73%

[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

Hyman¹,

Hsu²,

Jing³

et al. 1990

Neurogastroenterology Motil

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“…The small, but significant, leftward shift in the curve representing response to bethanechol dose suggests the possibility of a greater affinity of the muscarinic receptors in the proximal colon to bethanechol. Receptor binding studies in isolated cells from the rabbit colon also demonstrated different affinities for muscarinic agonists in the proximal and distal circular muscle (21), which are reflected in differences in contractility of the muscles to different agonists (13,22). Although both rabbit and human colons demonstrate different contractility between the proximal and distal colon, they differ in that in the rabbit distal circular colonic muscle develops greater active stress than the proximal muscle (13).…”

Section: Discussionmentioning

confidence: 99%

Response of Smooth Muscle from Proximal and Distal Human Colon

Snape

Mayer

Koelbel

et al. 1989

Neurogastroenterology Motil

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Regional differences in colonic motility may be responsible for the orderly transit of intraluminal contents through the colon. The aims of this study were to compare the effect of stretch on active and passive stress development in colonic muscle from the proximal and distal colon and to compare the responses of these tissues to KC1 or bethanechol stimulation. Strips of taenia or circular smooth muscle were obtained from the disease‐free segment of the colon removed for adenocarcinoma. Passive, active, and total isometric stress were measured on full‐thickness strips of circular or longitudinal taenial muscle stimulated with bethanechol (10−4 M) as the muscles were stretched to 120% of the length of optimum tension (Lo.) The tissues then were stimulated with increasing concentrations of KCI and bethanechol while being stretched at Lo. The active stress in the proximal circular muscle was greater at all levels of stretch than in distal circular or longitudinal muscle (p <.001). The resting and passive stress were greater in distal circular and longitudinal taenial muscle than in proximal circular muscle (p < .05). There was a dose‐dependent increase in stress development to bethanechol and KCl in each type of muscle. Proximal circular muscle had the greatest response. The EDSO was shifted to the right in distal circular muscle (2.6 ± 0.1 × 10−5 M) compared to proximal circular muscle (1.1 ± 0.1 × 10−5 M) (p < .001). These studies suggest that muscle stress differs in different locations of the colon and the role of active and passive stress development must be considered in models explaining in vivo colonic motility disturbances.

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“…In previous studies, the effect of neurotensin on gastrointestinal motility depended on the species, tissue, and experimental conditions (16)(17)(18)(19)(20). Neurotensin induced contractions in muscle strips from rat (18) and rabbit (16) stomachs and in rabbit colon (20). Neurotensin stimulated contraction of guinea pig ileum by inducing acetylcholine release from cholinergic nerve endings (17).…”

mentioning

confidence: 98%

Oral Neurotensin Increases Gastrointestinal Transit in Suckling Rats

Tomomasa,

Itoh,

Hyman

et al. 1991

J. pediatr. gastroenterol. nutr.

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SummarySeveral neuropeptides known to alter gastrointestinal motility are present in milk. We investigated the effect of gastric administration of neurotensin, bombesin, somatostatin, and vasoactive intestinal polypeptide on gastrointestinal motility in suckling rats. We gavage fed 7‐to 10‐day‐old rats with a meal consisting of 10 μl/g of body weight of 0.9% NaCl with 51Cr tracer and one of the peptides (0, 0.1, 10, and 1,000 ng/ml). We estimated the rates of gastric emptying and the small intestinal transit from the distribution of the radioactivity in the gut. Approximately one‐half of the counts emptied from the stomach in 15 min. Both gastric emptying and small intestinal transit were time dependent and were accelerated by metaclopramide and inhibited by butylscopolamine. Neurotensin 1 μg/ml accelerated the gastric emptying by 35% (p < 0.02). Small intestinal transit was also accelerated (p < 0.05). The other neuropeptides had no effect on gastric emptying and small intestinal transit. Neurotensin did not change either the gastric emptying or small intestinal transit in weaned rats, 40–50 days old, studied in the same manner. These data suggest that the intraluminal administration of neurotensin may increase gastrointestinal motility in suckling animals.

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Calcium dependence of neurotensin stimulation of circular colonic muscle of the rabbit

Cited by 10 publications

References 28 publications

[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

Response of Smooth Muscle from Proximal and Distal Human Colon

Oral Neurotensin Increases Gastrointestinal Transit in Suckling Rats

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Calcium dependence of neurotensin stimulation of circular colonic muscle of the rabbit

Cited by 10 publications

References 28 publications

[3H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

[3H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

Response of Smooth Muscle from Proximal and Distal Human Colon

Oral Neurotensin Increases Gastrointestinal Transit in Suckling Rats

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Product

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About

[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle

[³H]Nitrendipine Binding to Rabbit Colonic Smooth Muscle