Increase of metabolic activity and disruption of normal contractile protein distribution by bilirubin oxidation products in vascular smooth-muscle cells.
OBJECTIVE
Cerebral vasospasm is a common cause of morbidity and death following aneurysmal subarachnoid hemorrhage (SAH). Previous research has shown that bilirubin oxidation products (BOXes) are present in the cerebral spinal fluid in patients with SAH-induced cerebral vasospasm and can contribute to vasoconstriction and vasospasm in vitro and in vivo. The events leading to cerebral vasospasm are not understood; however, one component of the occlusion may be due to vascular remodeling. In this study the authors have investigated the actions of BOXes, okadaic acid ([OA], a phosphatase inhibitor), and phorbol-12 myristate-13 acetate ([PMA], a protein kinase activator) on vascular smooth-muscle cell (VSMC) morphology and metabolism.


METHODS
Immunohistochemical analysis was performed to assess VSMC morphology and alpha-smooth-muscle actin (alphaSMA) distribution following the application of BOXes, OA, or PMA. Changes in the level of lactate dehydrogenase (LDH) release and oxidative metabolism were also measured. The BOXes, OA, or PMA caused VSMCs to change their shape and exhibit altered alphaSMA distribution. These treatments increased LDH release (p < 0.05), which is an index of increased cell stress. Oxidative metabolism significantly increased at low and high doses of BOXes, that is, 143 +/- 8.5% and 180 +/- 11.8%, respectively (p < 0.0001). Both PMA and OA also caused a significant increase in metabolism.


CONCLUSIONS
The authors concluded that BOXes, OA, and PMA alter VSMC morphology and metabolic activity, events that have been observed during vascular remodeling. Although the mechanism remains unclear, the results indicate that BOXes may play a role in the vascular remodeling that occurs following aneurysmal SAH.
Lyons
Melissa A
MA
Department of Neurology, College of Medicine, University of Cincinnati, Ohio 45267, USA.
Shukla
Rakesh
R
Zhang
Kejun
K
Pyne
Gail J
GJ
Singh
Meha
M
Biehle
Susan J
SJ
Clark
Joseph F
JF
D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003285:Contractile Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D047908:Intracellular Signaling Peptides and Proteins; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000473:pathology; D019319:Okadaic Acid / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D013345:Subarachnoid Hemorrhage / Q000150:complications; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000031:analogs & derivatives* / Q000378:metabolism; D020301:Vasospasm, Intracranial / Q000209:etiology / Q000378:metabolism* / Q000473:pathology*; D000097847:Protein Phosphatase Inhibitory Proteins
D002352:Carrier Proteins; D003285:Contractile Proteins; D047908:Intracellular Signaling Peptides and Proteins; D007770:L-Lactate Dehydrogenase; D019319:Okadaic Acid; D044925:Oxidoreductases Acting on CH-CH Group Donors; D011506:Proteins; D013755:Tetradecanoylphorbol Acetate; C021042:protein phosphatase inhibitor-1; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins; C016658:phorbolol myristate acetate; C042401:bilirubin oxidase