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

Leoni, Renata F.; Paiva, Fernando F.; Henning, Erica C.; Nascimento, George Carlos do; Tannús, Alberto; Araújo, Dráulio Barros de; Silva, Afonso C.

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

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dc.contributor.author	Leoni, Renata F.
dc.contributor.author	Paiva, Fernando F.
dc.contributor.author	Henning, Erica C.
dc.contributor.author	Nascimento, George Carlos do
dc.contributor.author	Tannús, Alberto
dc.contributor.author	Araújo, Dráulio Barros de
dc.contributor.author	Silva, Afonso C.
dc.date.accessioned	2017-05-26T14:01:25Z
dc.date.available	2017-05-26T14:01:25Z
dc.date.issued	2011-06-25
dc.description.resumo	Hypertension afflicts 25% of the general population and over 50% of the elderly. In the presentwork, arterial spin labeling MRI was used to non-invasively quantify regional cerebral blood flow (CBF), cerebrovascular resistance and CO2 reactivity in spontaneously hypertensive rats (SHR) and in normotensive Wistar Kyoto rats (WKY), at two different ages (3 months and 10months) and under the effects of two anesthetics, α-chloralose and 2% isoflurane (1.5 MAC). Repeated CBF measurements were highly consistent, differing by less than 10% and 18% within and across animals, respectively. Under α-chloralose, whole brain CBF 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, CBF values increased significantly, and a linear relationship between CBF and PaCO2 levels was observed. In contrast, 2% isoflurane impaired cerebral autoregulation. Whole brain CBF in SHR was significantly higher than inWKYrats at normocapnia (young SHR: 139±25 ml/100 g/min; adult SHR: 104±23 ml/100 g/min; young WKY: 55±9ml/100 g/min; adult WKY: 71±19 ml/100 g/min). CBF values increased significantly with increasing CO2; however, there was a clear saturation of CBF at PaCO2 levels greater than 70 mm Hg in both young and adult rats, regardless of absolute CBF values, suggesting that isoflurane interferes with the vasodilatory mechanisms of CO2. This behavior was observed for both cortical and subcortical structures. Under either anesthetic, CO2 reactivity values in adult SHRwere decreased, confirming that hypertension, when combined with age, increases cerebrovascular resistance and reduces cerebrovascular compliance.	pt_BR
dc.identifier.issn	1053-8119
dc.identifier.uri	https://repositorio.ufrn.br/jspui/handle/123456789/23116
dc.language	eng	pt_BR
dc.rights	Acesso Aberto	pt_BR
dc.subject	Arterial spin labeling	pt_BR
dc.subject	Hypercapnia	pt_BR
dc.subject	Magnetic resonance imaging	pt_BR
dc.subject	Perfusion	pt_BR
dc.subject	Spontaneously hypertensive rat	pt_BR
dc.title	Magnetic resonance imaging quantification of regional cerebral blood flow and cerebrovascular reactivity to carbon dioxide in normotensive and hypertensive rats	pt_BR
dc.type	article	pt_BR