Endothelin-1 release from lamb ductus arteriosus: relevance to postnatal closure of the vessel.
Our previous investigations have shown that endothelin-1 (ET-1) is a singularly potent constrictor of the ductus arteriosus and that a cytochrome P-450 system located in the sarcolemma is crucial for the contractile response of the vessel to oxygen. We have now studied the release of ET-1 from isolated ductus arteriosus preparations of near-term fetal lambs. Preparations produced measurable amounts of ET-1 under basal conditions (about 0.04 pg/100 mg wet weight.min) both in the presence and absence of the endothelium. Anisomycin (10(-4) M) reduced this release by 50%, while thrombin (1 U/mL) doubled the release. Treatment with a CO mixture (CO/O2 ratio, 0.27) inhibited ET-1 release from intact and endothelium-denuded preparations. We propose that oxygen triggers closure of the ductus arteriosus at birth by causing a conformational change in a specific cytochrome P-450, which, in turn, provides the signal for the synthesis of the constrictor ET-1.
Coceani
F
F
Research Institute, Hospital for Sick Children, Toronto, Ont., Canada.
Kelsey
L
L
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004373:Ductus Arteriosus / Q000254:growth & development / Q000378:metabolism*; D016232:Endothelins / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D011247:Pregnancy; D011487:Protein Conformation; D012756:Sheep
D016232:Endothelins; D007457:Iodine Radioisotopes; D000841:Anisomycin; D003577:Cytochrome P-450 Enzyme System