Magnetic resonance imaging quantification of regional cerebral blood flow and cerebrovascular reactivity to carbon dioxide in normotensive and hypertensive rats

Autor(es)

Leoni, Renata F. ^{[1, 2]} ; Paiva, Fernando F. ^{[1, 3]} ; Henning, Erica C. ^[4] ; Nascimento, George C. ^[1] ; Tannus, Alberto ^[3] ; de Araujo, Draulio B. ^{[2, 5]} ; Silva, Afonso C. ^[1]

Afiliação do(s) autor(es)

^[1] Natl Inst Neurol Disorders & Stroke, Cerebral Microcirculat Unit, Lab Funct & Mol Imaging, NIH, Bethesda, MD 20892 - USA

^[2] Univ Sao Paulo, Dept Math & Phys, FFCLRP, BR-14040901 Ribeirao Preto, SP - Brazil

^[3] Univ Sao Paulo, CIERMag Ctr Imagens & Espectroscopia Vivo Ressona, Inst Phys Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[4] Natl Inst Neurol Disorders & Stroke, Sect Stroke Diagnost & Therapeut, Bethesda, MD 20892 - USA

^[5] Univ Fed Rio Grande do Norte, Hosp Univ Oliofre Lopes, BR-59012300 Natal, RN - Brazil

• Tipo de documento: Artigo Científico
• Fonte: NeuroImage; v. 58, n. 1, p. 75-81, SEP 1 2011.
• Citações Web of Science: 30

Resumo

Hypertension afflicts 25% of the general population and over 50% of the elderly. In the present work, arterial spin labeling MRI was used to non-invasively quantify regional cerebral blood flow (CBE), cerebrovascular resistance and CO(2) reactivity in spontaneously hypertensive rats (SHR) and in normotensive Wistar Kyoto rats (WKY), at two different ages (3 months and 10 months) and under the effects of two anesthetics, alpha-chloralose and 2% isoflurane (1.5 MAC). Repeated CBE measurements were highly consistent, differing by less than 10% and 18% within and across animals, respectively. Under alpha-chloralose, whole brain CBE at normocapnia did not differ between groups (young WKY: 61 3 ml/100 g/min; adult WKY: 62 +/- 4 ml/100 g/min; young SHR: 70 +/- 9 ml/100 g/min: adult SHR: 69 8 ml/100 g/min), indicating normal cerebral autoregulation in SHR. At hypercapnia, CBE values increased significantly, and a linear relationship between CBE and PaCO(2) levels was observed. In contrast, 2% isoflurane impaired cerebral autoregulation. Whole brain CBE in SHR was significantly higher than in WKY rats at normocapnia (young SHR: 139 +/- 25 ml/100 g/min; adult SHR: 104 +/- 23 ml/100 g/min; young WKY: 55 +/- 9 ml/100 g/min; adult WKY: 71 +/- 19 ml/100 g/min). CBE values increased significantly with increasing CO(2): however, there was a clear saturation of CBF at PaCO(2) levels greater than 70 mm Hg in both young and adult rats, regardless of absolute CBE values, suggesting that isoflurane interferes with the vasoclilatory mechanisms of CO(2). This behavior was observed for both cortical and subcortical structures. Under either anesthetic, CO(2) reactivity values in adult SHR were decreased, confirming that hypertension, when combined with age, increases cerebrovascular resistance and reduces cerebrovascular compliance. Published by Elsevier Inc. (AU)

• Processo FAPESP: 05/56663-1 - Centro de imagens e espectroscopia in vivo por ressonância magnética para estudo de modelos animais
• Beneficiário: Alberto Tannús
• Linha de fomento: Auxílio à Pesquisa - Programa CINAPCE - Temático
• Processo FAPESP: 06/05706-5 - Avaliação da resposta hemodinâmica em pacientes com estenose carotídea sob estado de hipercapnia
• Beneficiário: Renata Ferranti Leoni
• Linha de fomento: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 03/13399-7 - Desenvolvimento de metodologias para fmri com contrastes obtidos por bold e perfusao asl: abordagem com pulsos adiabaticos.
• Beneficiário: Fernando Fernandes Paiva
• Linha de fomento: Bolsas no Brasil - Doutorado