Nitric oxide-mediated modulation of the endothelin-1 signalling pathway in the human cardiovascular system.
1. We studied the ability of nitric oxide (NO) to physiologically antagonize endothelin-1 (ET-1) induced constrictions in human internal mammary artery (IMA). We also investigated the hypothesis that NO interacts directly with ET-receptor binding in human heart and aorta. 2. ET-1 potently contracted IMA (EC(50) 6.86 nM, 95% CI: 3.5 - 13.4 nM; n=12). The constrictor response to 10 nM ET-1 was fully reversed by the NO-donor diethylamine NONOate (DEA/NO; EC(50) 2.0 microM, 95% CI: 0.8 - 4.8 microM; n=5). The guanylate cyclase inhibitor ODQ (100 microM) reduced the response to DEA/NO but did not abolish it (E(MAX) 50.9+/-8.5% in the presence of ODQ; 113.0+/-8.4%, control). 3. The increase in cyclic GMP by 30 microM DEA/NO was abolished in the presence of 100 microM ODQ (n=6). 4. In saturation binding experiments the NO-donor Diethyltriamine NONOate (DETA/NO; 1 mM) caused a 90% reduction in maximum binding of [(125)I]-ET-1 in human heart, without affecting the affinity. This reduction in binding was abolished by haemoglobin. Pre-incubating either the radiolabel or the tissue with NO-donors did not reduce binding. A similar effect was observed in aortic smooth muscle. 5. We have shown that DEA/NO is able to reverse ET-1-induced contractions in the human vasculature. The binding studies suggest a direct interaction between NO and the ET receptor or receptor-ligand complex in human ventricular and aortic tissue. NO is released continuously in vivo, thus this apparent modification of ET-receptor binding may provide an additional mechanism by which NO counter-balances the effects of ET.
Wiley
K E
KE
Clinical Pharmacology Unit, University of Cambridge, Level 6, Centre for Clinical Investigation, Box 110, Addenbrooke's Hospital, Cambridge, CB2 2QQ. kew29@hermes.cam.ac.uk
Davenport
A P
AP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D006152:Cyclic GMP / Q000378:metabolism; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D005260:Female; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects; D013058:Mass Spectrometry; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009206:Myocardium / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D011869:Radioligand Assay; D017466:Receptors, Endothelin / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects; D016276:Ventricular Function
D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D008024:Ligands; D020030:Nitric Oxide Donors; D017466:Receptors, Endothelin; D009569:Nitric Oxide; D006162:Guanylate Cyclase; D006152:Cyclic GMP