EFFECTS OF ERGOTAMINE AND DIHYDROERGOTAMINE ON 5-HYDROXYTRYPTAMINE-2ARECEPTORS IN THE ISOLATED RAT AORTA

Citation
Ho. Kalkman et F. Schneider, EFFECTS OF ERGOTAMINE AND DIHYDROERGOTAMINE ON 5-HYDROXYTRYPTAMINE-2ARECEPTORS IN THE ISOLATED RAT AORTA, Pharmacology, 53(6), 1996, pp. 351-355
Citations number
22
Categorie Soggetti
Pharmacology & Pharmacy
Journal title
ISSN journal
00317012
Volume
53
Issue
6
Year of publication
1996
Pages
351 - 355
Database
ISI
SICI code
0031-7012(1996)53:6<351:EOEADO>2.0.ZU;2-G
Abstract
Ergotamine contracted isolated rat aorta rings with an intrinsic activ ity of 50% of that of 5-hydroxytryptamine (5-HT, 0.1 mmol/l). Dihydroe rgotamine did not contract the tissue, but insurmountably blocked cont raction in response to ergotamine and 5-HT. The 5-HT2A receptor antago nist, ketanserin (0.1 mu mol/l), inhibited ergotamine (pK(B) 8.0) and 5-HT (pK(B) 8.1) induced contractions. These results indicate that in the rat aorta ergotamine is a partial 5-HT2A receptor agonist, whilst dihydroergotamine is an insurmountable 5-HT2A receptor antagonist. The present data could explain why ergotamine displays more cardiovascula r and uterotonic side effects than dihydroergotamine.