EFFECTS OF ERGOTAMINE ON ISOLATED HUMAN VESSELS

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 252  (2) , 241-252
Abstract
In isolated human mesenteric and crural veins, ergotamine induced long-lasting contractions. These contractions were resistant to repeated wash-out and were not affected by .alpha.-adrenoceptor blockade but could be abolished by removal of extracellular Ca or by the presence of the Ca blocker nifedipine. In contrast to its effect on human mesenteric and crural veins, ergotamine had no contractile effect, but a marked relaxant effect on mesenteric arteries mediated via blockade of .alpha.-receptors. The ergotamine-induced contraction was not affected by indomethacin (0.28-2.8 .mu.M) nor was it influenced by serotonin (5-HT). In both mesenteric and crural veins the ergotamine-induced contraction was diminished by the 5-HT blocking agent, methysergide. In veins development of tachyphylaxis to 5-HT was demonstrated. Ergotamine has a direct contractile effect on isolated human mesenteric and crural veins. These effects are dependent on unhindered influx of extracellular Ca and are at least partly mediated via 5-HT receptors. In mesenteric arteries ergotamine acted as an .alpha.-adrenoceptor blocker and had no contractant effect.