A study of the mechanisms involved in the responses of vascular smooth muscle to 5-hydroxytryptamine
A study of the mechanisms involved in the responses of vascular smooth muscle to 5-hydroxytryptamine
In the present study, the mechanism involved in 5-HT-evoked contraction of the rabbit mesenteric artery, a small resistance vessel was investigated. In addition, the nature of the endothelium-dependent contractions induced by 5-HT in submaximally contracted preparations of the rabbit basilar artery, a cerebral artery, were also investigated.
In strips of the mesenteric artery which had been permeabilized with staphylococcus aureus α-toxin and bathed in a calcium-free intracellular solution, noradrenaline, caffeine and Ins 1,4,5P3 but not 5-HT induced transient contractions if preparations were first incubated in a calcium-containing solution. This suggests although significant intracellular calcium stores are present in this artery, that intracellular release does not play an important role in contractions to 5-HT.
However, 5-HT contracted α-toxin-permeabilized mesenteric artery preparations in the presence of raised, constant [Ca2+]i, suggesting that a component of the contractile response to 5-HT reflects an increase in myofilament calcium sensitivity. The protein kinase C inhibitor 1-(5-isoquinoline sulphonyl)-O-2-methylpiperazine (H-7) inhibited this response suggesting that protein kinase C may be involved.
Contractions to 5-HT in non-permeabilized rings of the mesenteric artery were greatly enhanced if preparations were pre-stimulated by 25.2mM KCI which, by itself, caused only a very small contraction. The responses were mimicked by the 5-HT1 agonist, 5-CT, and weakly antagonised by the 5-HT2 antagonist, ketanserin suggesting that 5-HT contracts the mesenteric artery by activating 5-HT1-like receptors. The 5-HT1D agonist sumatriptan also contracted the artery indicating that the receptor may be similar to the 5-HT1D receptor subtype.
University of Southampton
1994
Seager, Joanna Mary
(1994)
A study of the mechanisms involved in the responses of vascular smooth muscle to 5-hydroxytryptamine.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In the present study, the mechanism involved in 5-HT-evoked contraction of the rabbit mesenteric artery, a small resistance vessel was investigated. In addition, the nature of the endothelium-dependent contractions induced by 5-HT in submaximally contracted preparations of the rabbit basilar artery, a cerebral artery, were also investigated.
In strips of the mesenteric artery which had been permeabilized with staphylococcus aureus α-toxin and bathed in a calcium-free intracellular solution, noradrenaline, caffeine and Ins 1,4,5P3 but not 5-HT induced transient contractions if preparations were first incubated in a calcium-containing solution. This suggests although significant intracellular calcium stores are present in this artery, that intracellular release does not play an important role in contractions to 5-HT.
However, 5-HT contracted α-toxin-permeabilized mesenteric artery preparations in the presence of raised, constant [Ca2+]i, suggesting that a component of the contractile response to 5-HT reflects an increase in myofilament calcium sensitivity. The protein kinase C inhibitor 1-(5-isoquinoline sulphonyl)-O-2-methylpiperazine (H-7) inhibited this response suggesting that protein kinase C may be involved.
Contractions to 5-HT in non-permeabilized rings of the mesenteric artery were greatly enhanced if preparations were pre-stimulated by 25.2mM KCI which, by itself, caused only a very small contraction. The responses were mimicked by the 5-HT1 agonist, 5-CT, and weakly antagonised by the 5-HT2 antagonist, ketanserin suggesting that 5-HT contracts the mesenteric artery by activating 5-HT1-like receptors. The 5-HT1D agonist sumatriptan also contracted the artery indicating that the receptor may be similar to the 5-HT1D receptor subtype.
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Published date: 1994
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Local EPrints ID: 458454
URI: http://eprints.soton.ac.uk/id/eprint/458454
PURE UUID: 0ef5da55-ffdd-477c-9d29-42608118ffc0
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Date deposited: 04 Jul 2022 16:49
Last modified: 04 Jul 2022 16:49
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Author:
Joanna Mary Seager
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