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Abstract |
DOI (1-100 micrograms/kg i.v.) induced an increase in mean blood pressure in the anaesthetized rat.Similarly, in the pithed rat, DOI (1-100 micrograms/kg i.v.) induced a dose-dependent increase in mean blood pressure, as did 5-HT.However, in contrast to 5-HT, DOI did not change the heart rate in either intact or pithed rats.In the pithed rat, the dose-pressor response curves to both 5-HT and DOI were unaffected by MDL 72222 (5-HT3 receptor antagonist), spiroxatrine or (+/-)-pindolol (5-HT1A receptor antagonists), idazoxan (alpha 2-adrenoceptor blocking agent) and AR-C 239 (alpha 1-adrenoceptor blocking agent).Only the selective 5-HT2 receptor antagonist.LY 53857, significantly and dose dependently shifted to the right the dose-response curves to both 5-HT and DOI.These results indicated that DOI possesses 5-HT2 agonistic properties and that the pressor response induced by DOI in the pithed rat is mediated via 5-HT2 receptors. |
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