Vasoconstrictor activity of novel endothelin peptide, ET-1(1 - 31), in human mammary and coronary arteries in vitro.
1. The ability of the putative chymase product of big endothelin-1 (big ET-1), ET-1(1 - 31), to constrict isolated endothelium-denuded preparations of human coronary and internal mammary artery was determined. 2. pD2 values in coronary and mammary artery respectively were 8.21+/-0.12 (n=14) and 8.55+/-0.11 (n=12) for ET-1, 6.74+/-0.11 (n=16) and 7.10+/-0.08 (n=16) for ET-1(1 - 31) and 6.92+/-0.10 (n=15) and 7.23+/-0.11 (n=12) for big ET-1. ET-1(1 - 31) was significantly less potent than ET-1 (P<0.001, Student's t-test) and equipotent with big ET-1. 3. Vasoconstrictor responses to 100 - 700 nM ET-1(1 - 31) were significantly (P<0.05, Student's paired t-test) attenuated by the ET(A) antagonist PD156707 (100 nM). 4. There was no effect of the ECE inhibitor PD159790 (30 microM), the ECE/NEP inhibitor phosphoramidon (100 microM) or the serine protease inhibitor chymostatin (100 microM) on ET-1(1 - 31) responses in either artery. 5. Radioimmunoassay detected significant levels of mature ET in the bathing medium of coronary (1.6+/-0.5 nM, n=14) and mammary (2.1+/-0.6 nM, n=14) arteries, suggesting that conversion of ET-1(1 - 31) to ET-1 contributed to the observed vasoconstriction. 6. ET-1(1 - 31) competed for specific [(125)I]-ET-1 binding to ET(A) and ET(B) receptors in human left ventricle with a pooled K(D) of 71.6+/-7.0 nM (n=3). 7. Therefore, in human arteries the novel peptide ET-1(1 - 31) mediated vasoconstriction via activation of the ET(A) receptor. The conversion of ET-1(1 - 31) to ET-1, by an as yet unidentified protease, must contribute wholly or partly to the observed constrictor response. Chymase generated ET-1(1 - 31) may therefore represent an alternative precursor for ET-1 production in the human vasculature.
Maguire
J J
JJ
Clinical Pharmacology Unit, University of Cambridge, Level 6 Centre for Clinical Investigation, Box 110 Addenbrooke's Hospital, Cambridge CB2 2QQ. jjm1003@medschl.cam.ac.uk
Kuc
R E
RE
Davenport
A P
AP
D000328:Adult; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D001667:Binding, Competitive; D053818:Chymases; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004149:Dioxoles / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism / Q000494:pharmacology; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins / Q000378:metabolism / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology; D005260:Female; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects* / Q000502:physiology; D008666:Metalloendopeptidases; D008875:Middle Aged; D011498:Protein Precursors / Q000378:metabolism / Q000494:pharmacology*; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D004149:Dioxoles; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D016232:Endothelins; D007457:Iodine Radioisotopes; C093321:PD 156707; D011498:Protein Precursors; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D014662:Vasoconstrictor Agents; D012697:Serine Endopeptidases; D053818:Chymases; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D000072396:Endothelin-Converting Enzymes