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Oxyhemoglobin-induced cytotoxicity and arachidonic acid release in cultured bovine endothelial cells
K Takenaka1, N F Kassell, P L Foley
1Department of Neurological Surgery, University of Virginia, Charlottesville.
Background And Purpose:
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.