title: Nitric oxide mediates protective effect of endothelin receptor antagonism during myocardial ischemia and reperfusion.
abstract: Endothelin (ET) receptor antagonism protects from ischemia-reperfusion injury. We hypothesized that the cardioprotective effect is related to nitric oxide (NO) bioavailability. Buffer-perfused rat and mouse hearts were subjected to ischemia and reperfusion. At the onset of ischemia, the rat hearts received vehicle, the dual endothelin type A/type B (ETA/ETB) receptor antagonist bosentan (10 microM), the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA; 100 microM), the combination of bosentan and L-NMMA or the combination of bosentan, L-NMMA, and the NO substrate L-arginine (1 mM). Hearts from wild-type and endothelial NO synthase (eNOS)-deficient mice received either vehicle or bosentan. Myocardial performance, endothelial function, NO outflow, and eNOS expression were monitored. Bosentan significantly improved myocardial function during reperfusion in rats and in wild-type mice, but not in eNOS-deficient mice. The functional protection afforded by bosentan was inhibited by L-NMMA, whereas it was restored by L-arginine. Myocardial expression of eNOS (immunoblotting) increased significantly in bosentan-treated rat hearts compared with vehicle hearts. Recovery of NO outflow during reperfusion was enhanced in the bosentan-treated rat heart. The endothelium-dependent vasodilator adenosine diphosphate increased coronary flow by 18 +/- 9% at the end of reperfusion in the bosentan group, whereas it reduced coronary flow by 7 +/- 5% in the vehicle group (P < 0.001). The response to the endothelium-independent dilator sodium nitroprusside was not different between the two groups. In conclusion, the dual ETA/ETB receptor antagonist bosentan preserved endothelial and cardiac contractile function during ischemia and reperfusion via a mechanism dependent on endothelial NO production.
authors.affiliation: Department of Cardiology, Karolinska Hospital, 171 76 Stockholm, Sweden. adrian.gonon@medks.ki.se
authors.forename: Adrian T
authors.initials: AT
authors.lastname: Gonon
authors.forename: Deniz
authors.initials: D
authors.lastname: Erbas
authors.forename: Anders
authors.initials: A
authors.lastname: Bröijersén
authors.forename: Guro
authors.initials: G
authors.lastname: Valen
authors.forename: John
authors.initials: J
authors.lastname: Pernow
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D000077300:Bosentan; D002316:Cardiotonic Agents / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D065128:Endothelin Receptor Antagonists; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017202:Myocardial Ischemia / Q000378:metabolism*; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009599:Nitroprusside / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013449:Sulfonamides / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D002316:Cardiotonic Agents; D065128:Endothelin Receptor Antagonists; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D013449:Sulfonamides; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000244:Adenosine Diphosphate; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C496316:Nos3 protein, rat; D000077300:Bosentan