Dirnagl U, Pulsinelli W
Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York.
J Cereb Blood Flow Metab. 1990 May;10(3):327-36. doi: 10.1038/jcbfm.1990.61.
The relationship between systemic arterial pressure (SAP) and neocortical microcirculatory blood-flow (CBF) in areas of focal cerebral ischemia was studied in 15 spontaneously hypertensive rats (SHRs) anesthetized with halothane (0.5%). Ischemia was induced by ipsilateral middle cerebral artery/common carotid artery occlusion and CBF was monitored continuously in the ischemic territory using laser-Doppler flowmetry during manipulation of SAP with I-norepinephrine (hypertension) or nitroprusside (hypotension). In eight SHRs not subjected to focal ischemia, we demonstrated that 0.5% halothane and the surgical manipulations did not impair autoregulation. Autoregulation was partly preserved in ischemic brain tissue with a CBF of greater than 30% of preocclusion values. In areas where ischemic CBF was less than 30% of preocclusion values, autoregulation was completely lost. Changes in SAP had a greater influence on CBF in tissue areas where CBF ranged from 15 to 30% of baseline (9% change in CBF with each 10% change in SAP) than in areas where CBF was less than 15% of baseline (6% change in CBF with each 10% change in SAP). These findings demonstrate that the relationship between CBF and SAP in areas of focal ischemia is highly dependent on the severity of ischemia. Autoregulation is lost in a gradual manner until CBF falls below 30% of normal. In areas without autoregulation, the slope of the CBF/SAP relationship is inversely related to the degree of ischemia.
在15只使用0.5%氟烷麻醉的自发性高血压大鼠（SHR）中，研究了局灶性脑缺血区域全身动脉压（SAP）与新皮质微循环血流量（CBF）之间的关系。通过同侧大脑中动脉/颈总动脉闭塞诱导缺血，并在使用去甲肾上腺素（高血压）或硝普钠（低血压）操纵SAP期间，使用激光多普勒血流仪连续监测缺血区域的CBF。在8只未发生局灶性缺血的SHR中，我们证明0.5%氟烷和手术操作不会损害自动调节功能。当缺血脑组织的CBF大于闭塞前值的30%时，自动调节功能部分保留。在缺血CBF小于闭塞前值30%的区域，自动调节功能完全丧失。与CBF小于基线15%的区域相比，CBF在基线的15%至30%之间变化时（每10%的SAP变化导致CBF变化9%），SAP的变化对组织区域CBF的影响更大（每10%的SAP变化导致CBF变化6%）。这些发现表明，局灶性缺血区域CBF与SAP之间的关系高度依赖于缺血的严重程度。自动调节功能逐渐丧失，直到CBF降至正常的30%以下。在没有自动调节功能的区域，CBF/SAP关系的斜率与缺血程度呈负相关。
