Participation of H1-receptors in histamine-induced contraction and relaxation of horse coronary artery in vitro.
Abstract: The mechanisms of histamine-induced contraction and relaxation were investigated in rings isolated from a middle part of the left descending coronary arteries of horses. Intact and endothelium-denuded preparations were compared. Rings of horse coronary arteries contracted in response to histamine in a concentration dependent manner, but some of them relaxed with lower concentrations and contracted with higher concentrations. Removal of the endothelium abolished the relaxation and potentiated the contraction. The pD2 values were 4.70 +/- 0.08 in the rings with intact endothelium and 4.95 +/- 0.08 in endothelium-denuded rings. Histamine-induced contractions in intact and denuded preparations were not affected by an H2-antagonist, cimetidine, but were inhibited by an H1-antagonist, diphenhydramine in non-competitive manner in the rings with endothelium and in competitive manner in denuded rings. After precontraction with PGF2 alpha or norepinephrine, histamine relaxed preparations with intact endothelium (pD2 value, 7.80 +/- 0.11), although histamine-induced relaxations were not observed in denuded preparations. The relaxation was competitively inhibited by diphenhydramine. Relaxing response was significantly attenuated by methylene blue, quinacrine, L-nitro-arginine, gossypol and AA861 but not by indomethacin. These results suggest that the histamine-induced contraction and relaxation in horse coronary arteries are mediated mainly by H1-receptors in the smooth muscle and endothelium, respectively, and H1-receptor activation of endothelial cells may liberate vasodilator substances.
Publication Date: 1991-10-01 PubMed ID: 1684296DOI: 10.1292/jvms.53.789Google Scholar: Lookup
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- Journal Article
Summary
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This study looks into the behavior of histamine on horse coronary arteries in the lab, focusing mainly on its effect on H1-receptors resulting in contraction and relaxation of said arteries. The study demonstrates that histamine impacts the H1-receptors on both the smooth muscle and the endothelium, and may trigger the release of vasodilator substances.
Objective and Methodology
- The study focuses on discovering the functions of histamine on horse coronary arteries. Specifically, it investigates the contraction and relaxation caused by histamine in these arteries.
- Rings were isolated from the middle part of the left descending coronary arteries of horses and were subjected to varying concentrations of histamine. Both intact and endothelium-denuded preparations were compared.
Histamine’s Direct Effect
- When subjected to increasing concentrations of histamine, the rings of horse coronary arteries contracted. However, it was observed that lower concentrations triggered a relaxation response, and higher concentrations caused contraction.
- When the endothelium was removed, the relaxation effect was abolished and the contraction effect was potentiated.
Role of H1 and H2 Antagonists
- Histamine-induced contractions were not affected by an H2-antagonist (cimetidine), but were inhibited by an H1-antagonist (diphenhydramine). This suggests the significant role of H1-receptors in the contraction and relaxation effects.
- This inhibition by diphenhydramine was non-competitive in the rings with endothelium, while in the denuded rings it was competitive.
Effect of Precontraction and Relaxation
- When the rings were precontracted with PGF2 alpha or norepinephrine, exposure to histamine relaxed the preparations with an intact endothelium. This did not occur in the endothelium-denuded rings.
- This relaxation was competitively inhibited by diphenhydramine.
- Several substances such as methylene blue, quinacrine, L-nitro-arginine, gossypol and AA861 significantly reduced the relaxing effect, but indomethacin did not.
Conclusions
- Based on these results, the study suggests that histamine-induced contraction and relaxation in horse coronary arteries are predominantly influenced by H1-receptors.
- These H1-receptors are found in both the smooth muscle and endothelium cells of the arteries.
- Activation of H1-receptors in endothelial cells may release vasodilator substances which contribute to the observed relaxation effect.
Cite This Article
APA
Obi T, Miyamoto A, Matumoto M, Ishiguro S, Nishio A.
(1991).
Participation of H1-receptors in histamine-induced contraction and relaxation of horse coronary artery in vitro.
J Vet Med Sci, 53(5), 789-795.
https://doi.org/10.1292/jvms.53.789 Publication
Researcher Affiliations
- Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, Japan.
MeSH Terms
- Animals
- Coronary Vessels / drug effects
- Coronary Vessels / physiology
- Culture Techniques
- Endothelium, Vascular / drug effects
- Endothelium, Vascular / physiology
- Histamine / pharmacology
- Histamine H1 Antagonists / pharmacology
- Histamine H2 Antagonists / pharmacology
- Horses / physiology
- Muscle Contraction / drug effects
- Muscle Contraction / physiology
- Muscle Relaxation / drug effects
- Muscle Relaxation / physiology
- Muscle, Smooth, Vascular / drug effects
- Muscle, Smooth, Vascular / physiology
- Receptors, Histamine H1 / physiology
Citations
This article has been cited 2 times.- Xiong Y, Chen D, Lv B, Liu F, Yao Q, Tang Z, Lin Y. Effects of ginsenoside Re on rat jejunal contractility.. J Nat Med 2014 Jul;68(3):530-8.
- Miyamoto A, Nishio A. Vasomotor effects of histamine on bovine and equine basilar arteries in vitro.. Vet Res Commun 1994;18(6):447-56.
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