Tachykinin-mediated increase in motility acts independently of vasoactive intestinal polypeptide release in the canine ileum

1994 ◽  
Vol 72 (2) ◽  
pp. 109-112 ◽  
Author(s):  
E. G. Watson ◽  
J. E. T. Fox-Threlkeld ◽  
E. E. Daniel
Keyword(s):  
Gastrointestinal Tract ◽  
Substance P ◽  
Motor Activity ◽  
Vasoactive Intestinal Polypeptide ◽  
Neurokinin A ◽  
Significant Change ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Intestinal Polypeptide

Tachykinins induce motor activity in the canine ileum, and their mechanism of excitation may include inhibition of the release of a nonadrenergic, noncholinergic inhibitor, for which vasoactive intestinal polypeptide (VIP) is a candidate. Both substance P and neurokinin A produced a dose-dependent increase in ileal contractility with no significant change in VIP output. The highly selective NK1 agonist [Sar9, Met(O2)11]substance P and the highly selective NK2 agonist [Nle10]neurokinin A (4–10) also increased motor activity in the absence of any change in VIP released. These data suggest that the tachykinins produce motor activity in the canine ileum via a mechanism that does not involve changes in VIP output but may involve excitation through both NK1 and NK2 receptors.Key words: vasoactive intestinal polypeptide, tachykinins, gastrointestinal tract, motility.

An immunocytochemical study of regulatory peptides in the amphibian gastrointestinal tract

1986 ◽  
Vol 64 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. M. J. Buchan
Keyword(s):  
Gastrointestinal Tract ◽  
Substance P ◽  
Vasoactive Intestinal Polypeptide ◽  
Pancreatic Polypeptide ◽  
Endocrine Cells ◽  
Regulatory Peptides ◽  
Single Species ◽  
Gastric Inhibitory Polypeptide ◽  
Ambystoma Mexicanum ◽  
Intestinal Polypeptide

Samples from the gastrointestinal tract of two urodele and eight anuran species were investigated by immunocytochemical methods for the presence of structures immunoreactive with a range of antisera raised to the mammalian regulatory peptides. The regulatory peptides involved were gastrin, cholecystokinin, motilin, secretin, gastric inhibitory polypeptide, pancreatic glucagon, enteroglucagon, glicentin, neurotensin, somatostatin, pancreatic polypeptide, vasoactive intestinal polypeptide, substance P, Met-enkephalin, bombesin, and β-endorphin. In the majority of the species investigated, immunoreactive epithelial endocrine cells were demonstrated with the antisera to somatostatin, gastrin, enteroglucagon, and neurotensin. Motilin-containing cells were observed in a single species, Ambystoma mexicanum. Of the peptides detected within the mammalian innervation, vasoactive intestinal polypeptide, substance P, Met-enkephalin, and β-endorphin immunoreactive nerve fibres were seen. The distribution of the immunoreactive nerves differed significantly with species. Bombesin immunoreactivity was not seen within the innervation, although a population of endocrine cells was detected within the corpus of several species. No immunoreactivity was observed with the antisera to secretin, gastric inhibitory polypeptide, or pancreatic polypeptide in the species investigated.

Effects of Neuropeptides on Mucociliary Activity

1986 ◽  
Vol 95 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Sven Lindberg ◽  
Jan-Christer Hybbinette ◽  
Ulf Mercke
Keyword(s):  
Substance P ◽  
Vasoactive Intestinal Polypeptide ◽  
Dose Range ◽  
Dependent Manner ◽  
Feeding Artery ◽  
Maximal Increase ◽  
Dose Dependent ◽  
Photoelectric Technique ◽  
Intestinal Polypeptide

The effects of four neuropeptides, vasoactive intestinal polypeptide, enkephalin, bombesin, and substance P, on mucociliary activity in the rabbit maxillary sinus were investigated in vivo. The peptides were administered via the feeding artery (arteria maxillaris), and the resulting effects were registered with a noninvasive photoelectric technique. The peptides were tested in the dose range 0.0001 to 10 μg/kg body weight. The following results were observed: 1) vasoactive intestinal polypeptide and enkephalin did not influence mucociliary activity; 2) bombesin had only a slight accelerating effect on the mucociliary activity at doses of 0.1 to 10 μg/kg; and 3) substance P markedly accelerated the mucociliary activity in a dose-dependent manner in the dose range 0.01 to 10 μg/kg, the maximal increase being about 50%. The effect of substance P was atropine-resistant, and probably acted directly on the mucosa.

Tracheal smooth muscle responses to substance P and neurokinin A in the piglet

1992 ◽  
Vol 72 (3) ◽  
pp. 1090-1095 ◽  
Author(s):  
B. Haxhiu-Poskurica ◽  
M. A. Haxhiu ◽  
G. K. Kumar ◽  
M. J. Miller ◽  
R. J. Martin
Keyword(s):  
Smooth Muscle ◽  
Substance P ◽  
Muscle Contraction ◽  
Muscle Tension ◽  
Age Groups ◽  
Smooth Muscle Contraction ◽  
Tracheal Smooth Muscle ◽  
Neurokinin A ◽  
Dose Dependent Increase ◽  
Dose Dependent

The tachykinins substance P (SP) and neurokinin A (NKA) have been shown to induce airway smooth muscle contraction in mature animals, and the enzyme neutral endopeptidase (NEP) modulates this effect. We evaluated maturation of SP- and NKA-induced tracheal smooth muscle contraction and modulation of their effects by NEP in anesthetized, paralyzed, and artificially ventilated piglets less than 4 days, 2–3 wk, and 10 wk of age. Tracheal smooth muscle tension was measured in vivo from an open tracheal segment by use of a force transducer. Intravenous SP caused a dose-dependent increase in tracheal tension in all three age groups; however, the response in less than 4-day-old piglets was significantly weaker than in 2- to 3- and 10-wk-old piglets. NKA caused a dose-dependent increase in tracheal tension only in 2- to 3- and 10-wk-old piglets. The response of tracheal tension to NKA was weaker than the response to SP in all age groups. Atropine (2 mg/kg) significantly diminished the responses of tracheal tension to SP and NKA, indicating a cholinergic contribution to these responses at all ages. Intravenous thiorphan, a known NEP inhibitor, potentiated the effects of SP only in 2- to 3- and 10-wk-old piglets and did not affect the response of tracheal tension to NKA at any age. Biochemical analyses demonstrated a significant increase in tracheal NEP activity in comparably aged piglets over the first 10 wk of life.(ABSTRACT TRUNCATED AT 250 WORDS)

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