1P251 Supersensitivity to the 5-HT of the collateralized vascular bed in rabbit hindlinib was mediated by not only 5-HT2A receptor but also 5-HT1B receptor

• Published in: Journal of Pharmacological Sciences 2003, Vol.91 (suppl.1), p.150-150
• Main Authors: Chikaomi Yamada, Atsuto Ogata, Kazuo Miyazaki, Mayuko Toba, Akira Mizuno, Mayumi Furuya
• Format: Article
• Language: Japanese
• ISSN: 1347-8613

It has been reported that newly developed collateral vessels are more sensitive to 5-HT than normal vessels, and the 5-HT induced constriction is mediated by 5-HT2A receptor. However, not only 5-HT2A receptors but also another subtype, 5-HTIB receptors are expressed in the vascular smooth muscles. In the present study, we investigated the contribution of 5-HT1B receptor to the supersensitivity against 5-HT in the collateral vessels using a rabbit model of femoral artery ligation. The constriction of the collateral vessels was evaluated by the measurement of iliac arterial blood flow. A selective 5-HT1B agonist, sumatriptan (1-300μg/kg, i. v. ) reduced the collateralized iliac blood flow in a dose dependent manner, which was completely inhibited by the pretreatment with a selective 5-HT1B antagonist, GR127935 (0.3 mg/kg, i, v. ). 5-HT (0.1-30p g/kg, i. a. ) itself also decreased the collateralized iliac blood flow in a dose dependent manner. A 5-HT2A antagonist, ketanserin (0.1 mg/kg, i. v. ) inhibited the collateralized iliac blood flow reduction, when 5-HT was administered at a high-dose (30μg/kg). On the other hand, GR127935 antagonized the collateralized iliac blood flow reduction, when 5-HT was administered at lower-doses (0.1-10μg/kg). These data suggested that not only by 5-HT2A receptor, but also 5-HTIB receptor participate in the supersensitivity to 5-HT in the collateralized limbs.