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Article: Metoprolol reduces cerebral tissue oxygen tension after acute hemodilution in rats

TitleMetoprolol reduces cerebral tissue oxygen tension after acute hemodilution in rats
Authors
Issue Date2009
Citation
Anesthesiology, 2009, v. 111, n. 5, p. 988-1000 How to Cite?
AbstractBACKGROUND:: Perioperative β-blockade and anemia are independent predictors of increased stroke and mortality by undefined mechanisms. This study investigated the effect of β-blockade on cerebral tissue oxygen delivery in an experimental model of blood loss and fluid resuscitation (hemodilution). METHODS:: Anesthetized rats were treated with metoprolol (3 mg • kg) or saline before undergoing hemodilution with pentastarch (1:1 blood volume exchange, 30 ml • kg). Outcomes included cardiac output, cerebral blood flow, and brain (PBrO2) and kidney (PKO2) tissue oxygen tension. Hypoxia inducible factor-1α (HIF-1α) protein levels were assessed by Western blot. Systemic catecholamines, erythropoietin, and angiotensin II levels were measured. RESULTS:: Hemodilution increased heart rate, stroke volume, cardiac output (60%), and cerebral blood flow (50%), thereby maintaining PBrO2 despite an approximately 50% reduction in blood oxygen content (P < 0.05 for all). By contrast, PKO2 decreased (50%) under the same conditions (P < 0.05). β-blockade reduced baseline heart rate (20%) and abolished the compensatory increase in cardiac output after hemodilution (P < 0.05). This attenuated the cerebral blood flow response and reduced PBrO2 (50%), without further decreasing PKO2. Cerebral HIF-1α protein levels were increased in β-blocked hemodiluted rats relative to hemodiluted controls (P < 0.05). Systemic catecholamine and erythropoietin levels increased comparably after hemodilution in both groups, whereas angiotensin II levels increased only after β-blockade and hemodilution. CONCLUSIONS:: Cerebral tissue oxygen tension is preferentially maintained during hemodilution, relative to the kidney, despite elevated systemic catecholamines. Acute β-blockade impaired the compensatory cardiac output response to hemodilution, resulting in a reduction in cerebral tissue oxygen tension and increased expression of HIF-1α. © 2009 the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.
Persistent Identifierhttp://hdl.handle.net/10722/205729
ISSN
2015 Impact Factor: 5.264
2015 SCImago Journal Rankings: 2.162

 

DC FieldValueLanguage
dc.contributor.authorRagoonanan, Tenille E.-
dc.contributor.authorBeattie, William Scott-
dc.contributor.authorMazer, Cynthia David-
dc.contributor.authorTsui, Albert K Y-
dc.contributor.authorLeong-Poi, Howard-
dc.contributor.authorWilson, David F.-
dc.contributor.authorTait, Gordon A.-
dc.contributor.authorYu, Julie-
dc.contributor.authorLiu, Elaine-
dc.contributor.authorNoronha, Melissa-
dc.contributor.authorDattani, Neil D.-
dc.contributor.authorMitsakakis, Nicholas-
dc.contributor.authorHaré, Gregory M T-
dc.date.accessioned2014-10-06T08:02:16Z-
dc.date.available2014-10-06T08:02:16Z-
dc.date.issued2009-
dc.identifier.citationAnesthesiology, 2009, v. 111, n. 5, p. 988-1000-
dc.identifier.issn0003-3022-
dc.identifier.urihttp://hdl.handle.net/10722/205729-
dc.description.abstractBACKGROUND:: Perioperative β-blockade and anemia are independent predictors of increased stroke and mortality by undefined mechanisms. This study investigated the effect of β-blockade on cerebral tissue oxygen delivery in an experimental model of blood loss and fluid resuscitation (hemodilution). METHODS:: Anesthetized rats were treated with metoprolol (3 mg • kg) or saline before undergoing hemodilution with pentastarch (1:1 blood volume exchange, 30 ml • kg). Outcomes included cardiac output, cerebral blood flow, and brain (PBrO2) and kidney (PKO2) tissue oxygen tension. Hypoxia inducible factor-1α (HIF-1α) protein levels were assessed by Western blot. Systemic catecholamines, erythropoietin, and angiotensin II levels were measured. RESULTS:: Hemodilution increased heart rate, stroke volume, cardiac output (60%), and cerebral blood flow (50%), thereby maintaining PBrO2 despite an approximately 50% reduction in blood oxygen content (P < 0.05 for all). By contrast, PKO2 decreased (50%) under the same conditions (P < 0.05). β-blockade reduced baseline heart rate (20%) and abolished the compensatory increase in cardiac output after hemodilution (P < 0.05). This attenuated the cerebral blood flow response and reduced PBrO2 (50%), without further decreasing PKO2. Cerebral HIF-1α protein levels were increased in β-blocked hemodiluted rats relative to hemodiluted controls (P < 0.05). Systemic catecholamine and erythropoietin levels increased comparably after hemodilution in both groups, whereas angiotensin II levels increased only after β-blockade and hemodilution. CONCLUSIONS:: Cerebral tissue oxygen tension is preferentially maintained during hemodilution, relative to the kidney, despite elevated systemic catecholamines. Acute β-blockade impaired the compensatory cardiac output response to hemodilution, resulting in a reduction in cerebral tissue oxygen tension and increased expression of HIF-1α. © 2009 the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.-
dc.languageeng-
dc.relation.ispartofAnesthesiology-
dc.titleMetoprolol reduces cerebral tissue oxygen tension after acute hemodilution in rats-
dc.typeArticle-
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1097/ALN.0b013e3181b87f0e-
dc.identifier.pmid19809291-
dc.identifier.scopuseid_2-s2.0-70449585638-
dc.identifier.volume111-
dc.identifier.issue5-
dc.identifier.spage988-
dc.identifier.epage1000-
dc.identifier.eissn1528-1175-

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