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J Thorac Cardiovasc Surg 2007;133:13-20
© 2007 The American Association for Thoracic Surgery
Cardiopulmonary Support and Physiology |
a Department of Anesthesia, University of Toronto, St. Michaels Hospital, Seneca College, Toronto, Ontario, Canada
b Department of Physiology, University of Toronto, St. Michaels Hospital, Seneca College, Toronto, Ontario, Canada
c Division of Cardiology, University of Toronto, St. Michaels Hospital, Seneca College, Toronto, Ontario, Canada
d Biotechnology Centre for Applied Research and Training, Seneca College, Toronto, Ontario, Canada.
Presented in part at the Society of Cardiovascular Anesthesiologists Meeting, Miami, Fla, April 29, 2003.
Received for publication October 19, 2005; revisions received May 17, 2006; accepted for publication June 13, 2006. * Address for reprints: C David Mazer, MD, Professor, Department of Anesthesia, University of Toronto, St Michaels Hospital, 30 Bond St, Toronto, Ontario, M5B 1W8 Canada (Email: mazerd{at}smh.toronto.on.ca).
OBJECTIVE: Hemodilution and endothelial nitric oxide synthase genetic polymorphism may contribute to cerebral and renal injury after cardiopulmonary bypass. This study tested the hypothesis that cardiopulmonary bypass and anemia stimulate an increase in cerebral and renal endothelial nitric oxide synthase gene expression in an experimental model of cardiopulmonary bypass.
METHODS: Anesthetized rats underwent a sham procedure without cardiopulmonary bypass (sham, n = 5), normothermic bypass for 1 hour (CPB, n = 7), or bypass plus hemodilutional anemia (CPB anemia, n = 9). After 24 hours of recovery, RNA was extracted from the cerebral cortex, renal cortex, and renal medulla. Quantitative reverse transcriptase polymerase chain reaction was used to assess endothelial nitric oxide synthase messenger RNA levels in brain and kidney tissues.
RESULTS: The hemoglobin concentration of anemic CPB rats was significantly lower than that of nonanemic rats on bypass (64 ± 5 vs 99 ± 8 g · L1, P < .001). Cerebral cortical endothelial nitric oxide synthase messenger RNA levels were increased after cardiopulmonary bypass relative to those of the sham group (11.2 ± 4.2 vs 6.3 ± 1.5 fg, P = .031), without a further increase in anemic rats. Renal medullary endothelial nitric oxide synthase messenger RNA levels were significantly higher in the CPB anemia group than in the sham and CPB groups (7.1 ± 4.4 fg vs 1.8 ± 0.4 fg vs 3.0 ± 0.6 fg, P < .001). Renal cortical endothelial nitric oxide synthase messenger RNA levels did not change significantly.
CONCLUSIONS: Normothermic cardiopulmonary bypass was associated with higher endothelial nitric oxide synthase messenger RNA levels in kidney and brain than was the sham procedure 24 hours after cardiopulmonary bypass. Anemia accentuated the increase in renal medullary, but not cerebral cortical, endothelial nitric oxide synthase expression. These data provide an approach for exploring potential mechanisms by which endothelial nitric oxide synthase may contribute to renal and cerebral dysfunction after cardiopulmonary bypass and anemia.
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G. M. T. Hare, A. K. Y. Tsui, A. T. McLaren, T. E. Ragoonanan, J. Yu, and C. D. Mazer Anemia and Cerebral Outcomes: Many Questions, Fewer Answers Anesth. Analg., October 1, 2008; 107(4): 1356 - 1370. [Abstract] [Full Text] [PDF] |
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