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Home / Equine Research Bank / Vet Res Commun / The vasomotor effects of 5-hydroxytryptamine on equine basil...
Veterinary research communications1996; 20(1); 61-70; doi: 10.1007/BF00346578

The vasomotor effects of 5-hydroxytryptamine on equine basilar arteries in vitro.

Abstract: The vasomotor effects of 5-hydroxytryptamine (5-HT) on isolated equine basilar arteries were studied. 5-HT induced contractions of equine basilar arteries in a concentration-dependent manner, with a pEC50 value (with 95% confidence limits) of 7.35 (7.08-7.62). Similar results were obtained with endothelium-denuded basilar arteries. Contractions were not competitively inhibited by the 5-HT2 receptor antagonist ketanserin at low concentrations of 5-HT. Conversely, at high concentrations of 5-HT, contractions were inhibited by ketanserin in a concentration-dependent manner, with a pA2 value of 8.91 (8.62-9.20). The 5-HT1 and 5-HT2 receptor antagonist methiothepin shifted the concentration-response curve of 5-HT downwards and to the right in a concentration-dependent manner. In the presence of 10(-6) mol/L ketanserin, however, methiothepin antagonized 5-HT-induced contractions competitively with a pA2 value of 7.95 (7.59-8.31). The 5-HT3 receptor antagonist MDL 72222 had no effect on 5-HT-induced contractions. The findings of this study indicate that 5-HT1 and 5-HT2 receptors are located in equine basilar arterial smooth muscle cells, and that stimulation of these receptors results in contraction.
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Publication Date: 1996-01-01 PubMed ID: 8693702DOI: 10.1007/BF00346578Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates how 5-hydroxytryptamine, or 5-HT affects the contraction of basilar arteries in horses. The compound does induce contractions in a dose-dependent manner and this effect is observed even when the artery lacks an endothelium. Furthermore, the study identifies that these contractions are linked to the activity of 5-HT1 and 5-HT2 receptors.

Understanding the Study and Its Methodology

The study followed several steps including:

  • The research began with the examination of the vasomotor effects of 5-HT on isolated basilar arteries in horses. Vasomotor refers to the actions related to or effecting the diameter of blood vessels. 5-HT is a compound in the body that functions as a neurotransmitter and a smooth muscle stimulant.
  • The contractions that occurred were measured in terms of their pEC50 value. This is the negative logarithm to base 10 of the EC50, the concentration of a drug that gives half-maximal response. This was used to determine the effectiveness of 5-HT in causing contractions of the arteries.
  • Both endothelium-intact and endothelium-denuded arteries were tested to see if there were any changes in their reaction when exposed to 5-HT.
  • The researchers used different receptor antagonists (ketanserin, methiothepin, and MDL 72222) to observe their effects on the contractions caused by 5-HT. Antagonists are substances that block or suppress the activity of certain receptors in the body. Ketanserin is a 5-HT2 receptor antagonist, methiothepin blocks both 5-HT1 and 5-HT2 receptors, and MDL 72222 is a 5-HT3 receptor antagonist.

Findings & Implications

According to the research findings:

  • 5-HT did cause contractions in the equine basilar arteries in a dose-dependent manner.
  • Ketanserin did not inhibit these contractions at low concentrations of 5-HT. However, at higher concentrations, ketanserin did show a concentration-dependent inhibitory effect.
  • Methiothepin shifted the concentration-response curve of 5-HT downwards and to the right, indicating a decrease in the contractions caused by 5-HT. Yet, in the presence of ketanserin, methiothepin competitively antagonized contractions.
  • MDL 72222 had no effect on contractions.
  • A significant conclusion drawn from the results was that the equine basilar arterial smooth muscle cells contained 5-HT1 and 5-HT2 receptors, and the stimulation of these receptors results in contraction.

These results are important in the understanding of the physiological processes governing equine arterial contractions and could be a basis in medical treatment in relevant cases.

Cite This Article

APA
Miyamoto A, Obi T, Nishio A. (1996). The vasomotor effects of 5-hydroxytryptamine on equine basilar arteries in vitro. Vet Res Commun, 20(1), 61-70. https://doi.org/10.1007/BF00346578

Publication

Veterinary research communications
ISSN: 0165-7380
NlmUniqueID: 8100520
Country: Switzerland
Language: English
Volume: 20
Issue: 1
Pages: 61-70

Researcher Affiliations

Miyamoto, A
  • Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, Japan.
Obi, T
    Nishio, A

      MeSH Terms

      • Animals
      • Basilar Artery / drug effects
      • Basilar Artery / physiology
      • Dose-Response Relationship, Drug
      • Horses
      • Ketanserin / pharmacology
      • Methiothepin / pharmacology
      • Muscle Contraction / drug effects
      • Muscle Contraction / physiology
      • Muscle, Smooth, Vascular / drug effects
      • Muscle, Smooth, Vascular / physiology
      • Serotonin / pharmacology
      • Serotonin Antagonists / pharmacology
      • Serotonin Receptor Agonists / pharmacology

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      Citations

      This article has been cited 2 times.
      1. Islam MZ, Sawatari Y, Kojima S, Kiyama Y, Nakamura M, Sasaki K, Otsuka M, Obi T, Shiraishi M, Miyamoto A. Vasomotor effects of 5-hydroxytryptamine, histamine, angiotensin II, acetylcholine, noradrenaline, and bradykinin on the cerebral artery of bottlenose dolphin (Tursiops truncatus). J Vet Med Sci 2020 Oct 20;82(10):1456-1463.
        doi: 10.1292/jvms.20-0351pubmed: 32814751google scholar: lookup
      2. Ootawa T, Wu S, Sekio R, Smith H, Islam MZ, Nguyen HTT, Uno Y, Shiraishi M, Miyamoto A. Habu snakes (Protobothrops flavoviridis) show variation in thoracic aortic vasoreactivity between adjacent Japanese islands. J Vet Med Sci 2024 Feb 8;86(2):202-206.
        doi: 10.1292/jvms.23-0361pubmed: 38104972google scholar: lookup
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