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Characterization of endothelin receptors in the human umbilical artery and vein
Author(s) -
Bogoni G.,
Rizzi A.,
Calo G.,
Campobasso C.,
D'OrleansJuste P.,
Regoli D.
Publication year - 1996
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1996.tb16078.x
Subject(s) - endothelins , umbilical vein , umbilical artery , endothelin receptor , nifedipine , medicine , endothelin 1 , vein , receptor , endocrinology , pharmacology , chemistry , biology , fetus , biochemistry , calcium , in vitro , pregnancy , genetics
1 The aim of the present study was to characterize pharmacologically endothelin receptors that are present in human umbilical vessels. 2 Endothelin‐1 (ET‐1) and endothelin‐2 (ET‐2) are potent stimulants of both the human umbilical artery (pEC 50 7.9 and 7.5) and vein (pEC 50 8.1 and 8.0). Endothelin‐3 (ET‐3) is inactive on the artery but contracts the vein (pEC 50 7.6). IRL1620 is inactive in both vessels. The order of potency of agonists is suggestive of a typical ET A receptor in the artery (ET‐1 =ET‐2 > > ET‐3) and a mixture of ET A and ET B receptors in the vein (ET‐1 = ET‐2 ≥ ET‐3). 3 The selective ET A receptor antagonist, BQ123, competitively inhibits the effect of ET‐1 in the human umbilical artery (pA 2 6.9), while in the vein, only a mixture of BQ123 and BQ788 (a selective ET B antagonist) weakly displaces to the right the cumulative concentration‐response curve to ET‐1. Contractions induced by ET‐3 in the vein are inhibited by BQ788 (pA 2 7.6), but not by BQ123. 4 Inhibition of Ca 2+ channels by nifedipine (0.1 μ m ) is accompanied by a significant decrease of the maximal response to ET‐1 by 40% in the artery and by 30% in the vein. The response of the vein to ET‐3 is almost abolished by nifedipine. 5 The results indicate that: (i) endothelins contract the human isolated umbilical artery via stimulation of an ET A receptor type; (ii) the contraction induced by ET‐1 in the vein is mediated by both ET A and ET B receptors, while ET‐3 stimulates the ET B receptor; (iii) the contribution of Ca 2+ channels to the contraction mediated by the ET B receptor appears to be more important than to that mediated by the ET A receptor.