Effects of hemoglobin on heme oxygenase gene expression and viability of cultured smooth muscle cells.
Ferrous Hb contributes to cerebral vasospasm after subarachnoid hemorrhage, although the mechanisms involved are uncertain. The hypothesis that cytotoxic effects of ferrous Hb on smooth muscle cells contribute to vasospasm was assessed. Cultured rat basilar artery smooth muscle cells were exposed to pure Hb, dog erythrocyte hemolysate, or Hb breakdown products; and heme oxygenase (HO-1 and HO-2) and ferritin mRNA and protein were measured. Cytotoxicity was assessed by lactate dehydrogenase release and fluorescence assays. Pure Hb or hemolysate caused dose- and time-dependent increases in HO-1 mRNA and protein. Hemin was the component of Hb that increased HO-1 mRNA. Cycloheximide inhibited the increase in HO-1 mRNA in response to hemin. Ferritin protein heavy chain but not mRNA increased upon exposure of cells to Hb. Hemin and ferric but not ferrous Hb were toxic to smooth muscle cells. Toxicity was increased by exposure to Hb plus tin protoporphyrin IX. In conclusion, exposure of smooth muscle cells to Hb induces HO-1 mRNA and protein through pathways that involve new protein synthesis. Hemin is the component of Hb that induces HO-1. Hemin and ferric but not ferrous Hb are toxic.
Marton
L S
LS
Section of Neurosurgery, Department of Surgery, Pritzker School of Medicine, University of Chicago Medical Center, Chicago, Illinois 60637, USA.
Wang
X
X
Kowalczuk
A
A
Zhang
Z D
ZD
Windmeyer
E
E
Macdonald
R L
RL
D000818:Animals; D001488:Basilar Artery / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005293:Ferritins / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051547:Heme Oxygenase-1; D006427:Hemin / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism* / Q000494:pharmacology; D006461:Hemolysis; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis; D008665:Metalloporphyrins / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011524:Protoporphyrins / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020301:Vasospasm, Intracranial / Q000209:etiology / Q000378:metabolism*
D006454:Hemoglobins; D008665:Metalloporphyrins; D011500:Protein Synthesis Inhibitors; D011524:Protoporphyrins; D012333:RNA, Messenger; D006427:Hemin; D005293:Ferritins; D003513:Cycloheximide; C032628:tin protoporphyrin IX; D007770:L-Lactate Dehydrogenase; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1