Dependence of oxygen delivery on blood flow in rat brain: A 7 tesla nuclear magnetic resonance study
Dependence of oxygen delivery on blood flow in rat brain: A 7 tesla nuclear magnetic resonance study
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DOI：
10.1097/00004647-200003000-00007
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发表时间：
2000-03-01
影响因子：
6.3
通讯作者：
Rothman, D
中科院分区：
文献类型：
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作者：
Hyder, F;Kennan, RP;Rothman, D
采用磁共振成像（MRI）和光谱学（MRS）技术，在7 T磁场强度下，测定不同水平皮层活动的成年大鼠感觉运动皮层CBF和cmor2的变化。维持吗啡麻醉的大鼠，戊巴比妥和尼古丁分别产生低活性和高活性状态的过渡。在硫酸吗啡基础麻醉条件下，CBF为0.75 +/- 0.09 mL g（-1）。cmo_2为3.15±0.18 μ mol g(-1).min（-1）。戊巴比妥钠分别使CBF和cmo_2降低66% +/- 16%和61% +/- 6%（即“失活”）。相比之下，烟碱酒石酸氢分别使CBF和cmor2增加41% +/- 5%和30% +/- 3%（即“激活”）。氯氯蔗糖麻醉大鼠的静息CBF和cmor2值为0.40 +/- 0.09 mt g（-1）。Min（-1）和1.51±0.06 μ mol g（-1）。分别min(1)。前爪刺激后，CBF和ccro2分别比静息时（即“激活”）增加34% +/- 10%和26% +/- 12%。CBF和cmor2的增量变化，当从各自的控制条件中以“失活”和“激活”的百分比变化来表示时，在整个范围内与全局和局部扰动检查是线性的（R-2 = 0,997）。最近的一个模型支持了体内脑氧输送的紧密相关性，该模型假设毛细血管床的有效氧扩散系数D的变化与cmor2和CBF的改变有关。理论上，这种假设的毛细管床的功能特征可以通过D相对于CBF变化的分数变化的比率来评估，以欧姆表示。根据这里提供的体内数据，欧姆的计算值为0.81 +/- 0.23，这反过来对应于一个假设，即毛细管床的有效氧扩散率不是恒定的，而可能以类似于“失活”和“激活”的方式变化以满足局部需氧量的要求。
Magnetic resonance imaging (MRI) and spectroscopy (MRS) were used at a magnetic field strength of 7 T to measure CBF and CMRO2 in the sensorimotor cortex of mature rats at different levels of cortical activity. In rats maintained on morphine anesthesia, transitions to lower activity and higher activity states were produced by administration of pentobarbital and nicotine, respectively. Under basal conditions of morphine sulfate anesthesia, CBF was 0.75 +/- 0.09 mL g(-1).min(-1) and CMRO2 was 3.15 +/- 0.18 mu mol g(-1).min(-1). Administration of sodium pentobarbital reduced CBF and CMRO2 by 66% +/- 16% and 61% +/- 6%, respectively (i.e., "deactivation"). In contrast, administration of nicotine hydrogen tartrate increased CBF and CMRO2 by 41% +/- 5% and 30% +/- 3%, respectively (i.e., "activation"). The resting values of CBF and CMRO2 for alpha-chloralose anesthetized rats were 0.40 +/- 0.09 mt g(-1).min(-1) and 1.51 +/- 0.06 mu mol g(-1).min(-1), respectively. Upon forepaw stimulation, CBF and CMRO2 were focally increased by 34% +/- 10% and 26% +/- 12%, respectively, above the resting nonanesthetized values (i.e., "activation"). Incremental changes in CBF and CMRO2, when expressed as a percentage change for "deactivation" and "activation" from the respective control conditions, were linear (R-2 = 0,997) Over the entire range examined with the global and local perturbations. This tight correlation for cerebral oxygen delivery in vivo is supported by a recent model where the consequence of a changing effective diffusivity of the capillary bed for oxygen, D, has been hypothetically shown to be linked to alterations in CMRO2 and CBF. This assumed functional characteristic of the capillary bed can be theoretically assessed by the ratio of fractional changes in D with respect to changes in CBF, signified by Ohm. A value 0.81 +/- 0.23 was calculated for Ohm with the in vivo data presented here, which in turn corresponds to a supposition that the effective oxygen diffusivity of the capillary bed is not constant but presumably varies to meet local requirements in oxygen demand in a similar manner with both "deactivation" and "activation."