Regional cerebral blood flow and BOLD responses in conscious and anesthetized rats under basal and hypercapnic conditions: Implications for functional MRI studies
Regional cerebral blood flow and BOLD responses in conscious and anesthetized rats under basal and hypercapnic conditions: Implications for functional MRI studies
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DOI：
10.1097/01.wcb.0000054755.93668.20
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发表时间：
2003-04-01
影响因子：
6.3
通讯作者：
Duong, TQ
中科院分区：
文献类型：
--
作者：
Sicard, K;Shen, Q;Duong, TQ
麻醉剂广泛用于磁共振成像 (MRI) 研究以避免运动伪影，相对于清醒状态，麻醉剂可能对脑血流量 (CBF) 和脑血管耦合产生深远影响。使用连续动脉自旋标记技术和平面回波成像采集技术，在基础和高碳酸血症条件下，对清醒和麻醉（2%异氟烷）大鼠进行定量CBF和组织氧合（血氧水平依赖性[BOLD]）测量。所有基础血气均在生理范围内。清醒状态下血压、呼吸和心率均在生理范围内，但麻醉状态下则降低（P < 0.05）。区域 CBF 不均匀，在清醒和麻醉条件下，全脑 CBF 值分别为 0.86 +/- 0.25 和 1.27 +/- 0.29 mL (.) g(-1) (.) min(-1)。令人惊讶的是，与清醒状态相比，异氟烷麻醉条件下的 CBF 明显更高（不同大脑条件下为 20% 至 70%）（P < 0.01）。高碳酸血症降低 pH 值，增加 PCO2 和 PO2 在 5% CO2 挑战期间，在清醒和麻醉条件下，CBF 分别增加 51±11% 和 25±4%，BOLD 增加 7.3 +/- 0.7% 和 5.4 +/- 0.4%。在 10% CO2 挑战期间，CBF 增加了 158 +/- 28% 和 47 +/- 11%，BOLD 增加了 12.5 +/- 0.9% 和 7.2 +/- 0.5%。由于清醒状态下 CBF 和 BOLD 反应明显较高，而血气分析无统计学差异，因此得出结论，麻醉剂抑制了脑血管反应性。这项研究还表明，灌注和基于灌注的功能性 MRI 可以在清醒的动物中进行。
Anesthetics, widely used in magnetic resonance imaging (MRI) studies to avoid movement artifacts, could have profound effects on cerebral blood flow (CBF) and cerebrovascular coupling relative to the awake condition. Quantitative CBF and tissue oxygenation (blood oxygen level-dependent [BOLD]) were measured, using the continuous arterial-spinlabeling technique with echo-planar- imaging acquisition, in awake and anesthetized (2% isoflurane) rats under basal and hypercapnic conditions. All basal blood gases were within physiologic ranges. Blood pressure, respiration, and heart rates were within physiologic ranges in the awake condition but were depressed under anesthesia (P < 0.05). Regional CBF was heterogeneous with whole-brain CBF values of 0.86 +/- 0.25 and 1.27 +/- 0.29 mL (.) g(-1) (.) min(-1) under awake and anesthetized conditions, respectively. Surprisingly, CBF was markedly higher (20% to 70% across different brain conditions) under isoflurane-anesthetized condition compared with the awake state (P < 0.01). Hypercapnia decreased pH, and increased PCO2 and PO2 During 5% CO2 challenge, under awake and anesthetized conditions, respectively, CBF increased 51 11% and 25 4%, and BOLD increased 7.3 +/- 0.7% and 5.4 +/- 0.4%. During 10% CO2 challenge, CBF increased 158 +/- 28% and 47 +/- 11%, and BOLD increased 12.5 +/- 0.9% and 7.2 +/- 0.5%. Since CBF and BOLD responses were substantially higher under awake condition whereas blood gases were not statistically different, it was concluded that cerebrovascular reactivity was suppressed by anesthetics. This study also shows that perfusion and perfusion-based functional MRI can be performed in awake animals.