Endothelin-converting enzyme and its in vitro and in vivo inhibition.
We investigated endothelin (ET)-converting enzyme and its localization in the vasculature. The membrane and cytosol fractions of cultured endothelial cells of bovine carotid artery contain phosphoramidon-sensitive ET-converting enzymes, and their molecular weights are about 100 and 540 kDa, respectively. The specific conversion of big ET-1 by these enzymes proceeds at pH 7.0 +/- 0.5, and it is inhibited by EDTA, o-phenanthroline, and phosphoramidon. Big ET-3 is converted by the membrane enzyme at a rate about one-tenth that of big ET-1, but it is not converted by the cytosol enzyme. Big ET-1 (but not ET-1)-induced hypertension in rats was remarkably suppressed by pretreatment with phosphoramidon, and big ET-1 (but not ET-1)-induced contraction of isolated coronary arteries, either with or without the endothelium, was substantially suppressed by phosphoramidon. These results suggest an essential role of phosphoramidon-sensitive enzyme(s) in the vascular conversion of big ET-1, and the existence of such enzymes also in nonendothelial cells. We found three converting enzymes operating at different optimal pH values in noncultured vascular smooth muscle cells; two pepstatin-sensitive, cytosolic acid proteinases and a phosphoramidon-sensitive neutral enzyme(s) in the membrane and cytosol. All of these findings strongly suggest the importance of phosphoramidon-sensitive neutral enzymes in the vascular conversion of big ET-1.
Yano
M
M
Biochemistry, Central Research Laboratory, Banyu Pharmaceutical Co., Ltd., Tokyo, Japan.
Okada
K
K
Takada
J
J
Hioki
Y
Y
Matsuyama
K
K
Fukuroda
T
T
Noguchi
K
K
Nishikibe
M
M
Ikemoto
F
F
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries / Q000201:enzymology; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D019332:Endothelin-1; D000072396:Endothelin-Converting Enzymes; D016232:Endothelins / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000201:enzymology; D006020:Glycopeptides / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008666:Metalloendopeptidases; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011498:Protein Precursors / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D013552:Swine
D019332:Endothelin-1; D016232:Endothelins; D006020:Glycopeptides; D011498:Protein Precursors; D016282:Aspartic Acid Endopeptidases; D008666:Metalloendopeptidases; D000072396:Endothelin-Converting Enzymes; C008890:phosphoramidon