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Uptake of 5‐hydroxytryptamine by equine digital vein endothelial cells: inhibition by amines found in the equine caecum

Uptake of 5‐hydroxytryptamine by equine digital vein endothelial cells: inhibition by amines... Summary Reasons for performing study: 5‐hydroxytryptamine (5‐HT; serotonin) is a potent vasoconstrictor of equine digital blood vessels and has been implicated in the pathogenesis of acute laminitis. Objectives: The aims of this study were firstly to examine whether cells of the digital blood vessel wall exhibited an active uptake mechanism for 5‐HT and to characterise its efficiency; and secondly, to study the potential inhibitory effect on this process of other amines, produced in the equine caecum. Methods: Confluent monolayers of equine digital vein endothelial cells (EDVEC) and equine digital vein smooth muscle cells (EDVSMC) were incubated with (3H)5‐HT (0.1–250 μmol/l) and the total and active uptake calculated. Equine pulmonary vein endothelial cells (EPVEC) were used as a positive control. Results: Both EDVEC and EDVSMC showed uptake of (3H)5‐HT by nonfaci litated diffusion; however, only EDVEC showed evidence of saturable facilitated uptake mechanism, with a Km of 41.6 ± 9.3 μmol/l, which was significantly higher than that of EPVEC (9.9 ± 2.1 μmol/l). All 6 caecally‐derived amines examined (tyramine, spermine, isoamylamine, tryptamine, phenylethylamine and isobutylamine) inhibited the total uptake of (3H)5‐HT in a concentration‐dependent manner, tyramine having the lowest IC50 (3.7 × 10−6 mol/l). Conclusions: These data suggest that facilitated uptake into the endothelium could play a role in moderating the vasoconstrictor response to 5‐HT in the equine digital circulation. Potential clinical relevance: The vasoconstrictor action of 5‐HT could be potentiated by gut‐derived amines, providing a feasible link between GI disturbances and the pathophysiology of laminits. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Equine Veterinary Journal Wiley

Uptake of 5‐hydroxytryptamine by equine digital vein endothelial cells: inhibition by amines found in the equine caecum

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References (43)

Publisher
Wiley
Copyright
2003 EVJ Ltd
ISSN
0425-1644
eISSN
2042-3306
DOI
10.2746/042516403776114171
Publisher site
See Article on Publisher Site

Abstract

Summary Reasons for performing study: 5‐hydroxytryptamine (5‐HT; serotonin) is a potent vasoconstrictor of equine digital blood vessels and has been implicated in the pathogenesis of acute laminitis. Objectives: The aims of this study were firstly to examine whether cells of the digital blood vessel wall exhibited an active uptake mechanism for 5‐HT and to characterise its efficiency; and secondly, to study the potential inhibitory effect on this process of other amines, produced in the equine caecum. Methods: Confluent monolayers of equine digital vein endothelial cells (EDVEC) and equine digital vein smooth muscle cells (EDVSMC) were incubated with (3H)5‐HT (0.1–250 μmol/l) and the total and active uptake calculated. Equine pulmonary vein endothelial cells (EPVEC) were used as a positive control. Results: Both EDVEC and EDVSMC showed uptake of (3H)5‐HT by nonfaci litated diffusion; however, only EDVEC showed evidence of saturable facilitated uptake mechanism, with a Km of 41.6 ± 9.3 μmol/l, which was significantly higher than that of EPVEC (9.9 ± 2.1 μmol/l). All 6 caecally‐derived amines examined (tyramine, spermine, isoamylamine, tryptamine, phenylethylamine and isobutylamine) inhibited the total uptake of (3H)5‐HT in a concentration‐dependent manner, tyramine having the lowest IC50 (3.7 × 10−6 mol/l). Conclusions: These data suggest that facilitated uptake into the endothelium could play a role in moderating the vasoconstrictor response to 5‐HT in the equine digital circulation. Potential clinical relevance: The vasoconstrictor action of 5‐HT could be potentiated by gut‐derived amines, providing a feasible link between GI disturbances and the pathophysiology of laminits.

Journal

Equine Veterinary Journal – Wiley

Published: Mar 1, 2003

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