Mechanism of oxyhemoglobin-induced release of endothelin-1 from cultured vascular endothelial cells and smooth-muscle cells.
Release of endothelin-1 from cultured endothelial cells can be induced with oxyhemoglobin (oxyHb). The present study was conducted to explore whether oxyHb affects the release of endothelin-1 and the induction of endothelin-1 messenger ribonucleic acid (mRNA) and to examine the mechanism whereby oxyHb induces endothelin-1 production in cultured vascular smooth-muscle cells as well as in cultured endothelial cells. Oxyhemoglobin produces concentration-dependent (0.1 to 10 microM) and time-dependent (0 to 24 hours) increases in immunoreactive endothelin-1 in conditioned medium from bovine arterial endothelial cells. Oxyhemoglobin induces immunoreactive endothelin-1 in rat aortic smooth-muscle cells in the same fashion, although the rate is 30-fold less than that of endothelial cells. This promoting effect is much higher than that of other stimulators such as thrombin and phorbol 12-myristate 13-acetate. Northern blot analysis of total RNA from endothelial cells also showed endothelin-1 mRNA induction. Staurosporine, a protein kinase C (PKC) inhibitor, inhibited oxyHb-induced endothelin-1 production in both vascular endothelial and smooth-muscle cells, whereas an increase of intracellular cyclic adenosine monophosphate (cAMP) by forskolin or an addition of 8-bromo-cAMP only inhibited this effect in smooth-muscle cells. These findings suggest that oxyHb-induced endothelin-1 production in endothelial cells is regulated by PKC, and in smooth-muscle cells by both PKC and the cAMP-dependent pathway. The production of endothelin, the most potent vasoconstrictor, in both vascular endothelial and smooth-muscle cells by oxyHb may have significance in the pathogenesis of cerebral vasospasm.
Kasuya
H
H
Section of Neurosurgery, University of Chicago, Illinois.
Weir
B K
BK
White
D M
DM
Stefansson
K
K
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002417:Cattle; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016232:Endothelins / Q000235:genetics / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008706:Methemoglobin / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010108:Oxyhemoglobins / Q000494:pharmacology / Q000502:physiology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012313:RNA / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012016:Reference Values; D019311:Staurosporine; D013917:Thrombin / Q000494:pharmacology
D000470:Alkaloids; D016232:Endothelins; D010108:Oxyhemoglobins; D012333:RNA, Messenger; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D012313:RNA; D008706:Methemoglobin; D011493:Protein Kinase C; D013917:Thrombin; D019311:Staurosporine