Oxyhemoglobin-induced cytotoxicity and arachidonic acid release in cultured bovine endothelial cells.
OBJECTIVE
An impairment of endothelial function is associated with vasospasm after subarachnoid hemorrhage. Oxyhemoglobin is considered to be a critical trigger in the pathogenesis of vasospasm. The present studies examined the direct effects of oxyhemoglobin on cultured endothelial cells from bovine carotid artery.


METHODS
Confluent endothelial cells were treated with oxyhemoglobin, and the following were studied: 1) cell morphology, 2) cell density, and 3) the release of radiolabel from [3H]arachidonic acid-treated cells.


RESULTS
Endothelial cells exposed to oxyhemoglobin exhibited detachment vacuoles, and cell density was significantly decreased in time- and dose-dependent manners. Superoxide dismutase, a free radical scavenger, provided partial protection against the cytotoxic effects of oxyhemoglobin. The release of radiolabel from [3H]arachidonic acid-treated cells was increased by oxyhemoglobin in time- and dose-dependent manners. Treatment with an inhibitor of phospholipase A2 or a calcium chelator inhibited the effects of oxyhemoglobin on arachidonic acid release and cellular viability.


CONCLUSIONS
Oxyhemoglobin exerts a direct cytotoxic effect on cultured endothelial cells, and this effect is associated with increased release from [3H]arachidonic acid-labeled cells. Phospholipase A2 and free radicals appear to participate in the pathogenesis of endothelial cell damage. Oxyhemoglobin-induced compromise of endothelial cells may contribute to cerebrovascular pathology.
Department of Neurological Surgery, University of Virginia, Charlottesville.
K
K
Takenaka
N F
NF
Kassell
P L
PL
Foley
K S
KS
Lee
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002417:Cattle; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D003603:Cytotoxins / Q000633:toxicity; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid; D004730:Endothelium, Vascular / Q000187:drug effects*; D002546:Ischemic Attack, Transient / Q000503:physiopathology; D010108:Oxyhemoglobins / Q000037:antagonists & inhibitors / Q000633:toxicity*; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D013482:Superoxide Dismutase / Q000494:pharmacology; D014316:Tritium; D014841:von Willebrand Factor / Q000032:analysis
D003603:Cytotoxins; D010108:Oxyhemoglobins; D014841:von Willebrand Factor; D014316:Tritium; D016718:Arachidonic Acid; D004533:Egtazic Acid; D013482:Superoxide Dismutase; D010741:Phospholipases A; D054467:Phospholipases A2