title: Comparison of vasodilators in human internal mammary artery: ghrelin is a potent physiological antagonist of endothelin-1.
abstract: 1 The potential vasodilator function of the peptide ghrelin, recently identified as the endogenous ligand of the growth hormone secretagogue orphan receptor (GHS-R), was investigated in human endothelium-denuded internal mammary artery. The peptide endothelin-1 (ET-1) is a potent and long-lasting vasoconstrictor. Comparisons were made with established and putative endogenous vasodilators to determine if any could reverse ET-1-induced vasoconstriction in this vessel. 2 Ghrelin (0.1-300 nM) potently dilated 10 nM ET-1-induced constrictions (pD(2) 8.39+/-0.29; E(MAX) 63+/-5.6%; n=9/14, responders/total). 3 ANP (pD(2) 7.75+/-0.14; E(MAX) 106+/-2.0; n=5/5) and CGRP (pD(2) 8.08+/-0.17; E(MAX) 76+/-15% n=5/6) both produced complete reversal of the constrictor response to ET-1 (E(MAX) not significantly different from 100%, P>0.05 one-sample t-test). 4 The following caused partial reversal of the ET-1 response: Adrenomedullin (n=9/9) and two peptides derived from proadrenomedullin, PAMP-12 (n=6/7) and PAMP-20 (n=9/9) (pD(2) values 7.63+/-0.28, 7.97+/-0.23 and 8.51+/-0.29; E(MAX) 58+/-7.3, 54+/-10 and 51+/-7.8% respectively). Unexpectedly, amylin was only 2 fold less potent than CGRP, although there was less than 50% reversal of the ET-1 constriction (pD(2) 7.86+/-0.30; E(MAX) 41+/-5.4%; n=7/9). CNP (n=6/6) also partially reversed constrictions to ET-1 (E(MAX) 53+/-6.3; pD(2) 8.07+/-0.38). 5 BNP (n=4/5) and PGI(2) (n=6/8) were weak vasodilators, since concentration-response curves failed to reach a maximum within the range tested. PGE(2) caused a small dilatation in some vessels (E(MAX) 17+/-2.1%; pD(2) 8.63+/-0.36; n=4/8). 6 We have demonstrated ghrelin to be an effective, endothelium-independent vasodilator of the long-lasting constrictor ET-1 in human arteries producing responses similar to those of adrenomedullin (P>0.05, ANOVA). British Journal of Pharmacology (2002) 136, 1146-1152
authors.affiliation: Clinical Pharmacology Unit, University of Cambridge, Level 6, Centre for Clinical Investigation, Box 110, Addenbrooke's Hospital, UK. kew29@hermes.cam.ac.uk
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Wiley
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Davenport
mesh_terms: D000328:Adult; D000368:Aged; D019332:Endothelin-1 / Q000037:antagonists & inhibitors*; D005260:Female; D054439:Ghrelin; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects* / Q000502:physiology; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D036361:Peptide Hormones / Q000494:pharmacology / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D019332:Endothelin-1; D054439:Ghrelin; D036361:Peptide Hormones; D014665:Vasodilator Agents