Involvement of nitric oxide in fading of 5-hydroxytryptamine-induced vasocontraction in rat isolated vena portae smooth muscle.
OBJECTIVE
The aim of the present study was to investigate a nitric oxide (NO) involvement in the mediation of a 5-HT-induced vasoconstrictions response in the rat portal vein in vitro.


METHODS
Isolated rat portal vein preparations obtained after dissection were placed in organ baths for isometric force measurement via a strain gauge.


RESULTS
5-hydroxytryptamine (5-HT) in concentrations ranging from 3x10(-8) M to 3x10(-4) M contracted portal vein preparations (EC50= 7x10(-7) M) in a concentration dependent manner. The vasoconstrictions induced by 5-HT was significantly increased in endothelium-denuded vessels. Pre-treatment with N(omega)-nitro-L-arginine methyl Ester (L-NAME 100 microM) enhanced the contractive response to 5-HT either in intact- or denuded endothelium vessels. Whereas, ketanserin (0.1 microM) abolished 5-HT-induced vasoconstrictions (EC50= 4.6x10(-8) M). Furthermore, a non-selective 5-HT receptors agonist, sumatriptan, (1x10(-10 )M - 1x10(-5) M) induced a reduction of spontaneous rhythmic contractions either in endothelium-intact or in endothelium -denuded vessels. However, 5-HT-induced vasoconstriction was unaffected by propranolol (10 microM).


CONCLUSIONS
These findings are consistent with the hypothesis that the vasoconstrictor activity of 5-HT in vascular smooth muscle was mediated by activation of 5-HT1B/D and 5-HT2B receptors subtypes involving the endothelium (NO) dependent mechanism.
Datté
J Y
JY
Laboratoire de Nutrition & Pharmacologie, Département BA-PA, UFR-Biosciences, Cocody Université, Abidjan, Côte d'Ivoire. yaodj@ci.refer.org
Offoumou
M A
MA
D000818:Animals; D004347:Drug Interactions; D066298:In Vitro Techniques; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000502:physiology*; D011169:Portal Vein / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D011921:Rats, Inbred WKY; D044302:Receptor, Serotonin, 5-HT1B / Q000502:physiology; D044346:Receptor, Serotonin, 5-HT1D / Q000502:physiology; D044403:Receptor, Serotonin, 5-HT2B / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D018170:Sumatriptan / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D044302:Receptor, Serotonin, 5-HT1B; D044346:Receptor, Serotonin, 5-HT1D; D044403:Receptor, Serotonin, 5-HT2B; D012702:Serotonin Antagonists; D014662:Vasoconstrictor Agents; D009569:Nitric Oxide; D012701:Serotonin; D018170:Sumatriptan; D007650:Ketanserin; D019331:NG-Nitroarginine Methyl Ester