Wei H M, Chen W Y, Sinha A K, Weiss H R
Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway 08854.
J Cereb Blood Flow Metab. 1993 Mar;13(2):269-75. doi: 10.1038/jcbfm.1993.33.
This study evaluated the hypothesis that the sympathetic nervous system was one of the factors increasing the heterogeneity of cerebrocortical venous O2 saturation and this heterogeneity would be greater during hypoxia when cervical sympathetic activity was elevated. Thirty-two male Long-Evans rats were either sham operated (n = 16) or received bilateral cervical sympathectomy (n = 16). One-half of the animals (n = 8) in each treatment were challenged by hypoxia (8% O2 in N2). Cerebral blood flow was determined in five brain regions with [14C]iodoantipyrine. Oxygen saturation was measured microspectrophotometrically in small cerebrocortical arteries and veins. The degree of hypoxic hyperemia was not significantly different between sham-operated and sympathectomized rats. Cortical venous O2 saturations, indicating the balance between O2 supply and consumption, were significantly more heterogeneous in the sham-operated group under both normoxic and hypoxic conditions. The coefficient of variation (CV = 100 x SD/mean) for the normoxic sham-operated animals was 24.9% and the average venous O2 saturation was 53.8%. During hypoxia, venous O2 saturation was significantly decreased to 43.1% without a change in CV (24.5%). Sympathectomy significantly reduced this heterogeneity through a reduction in the number of low O2 saturation veins (CV = 13.2%) under normoxic conditions and the effect was similar under hypoxic conditions (CV = 15.3%). In both sham-operated and sympathectomized groups, hypoxia elicited a significantly higher cerebrocortical O2 consumption. Thus, bilateral cervical sympathectomy improved the O2 supply in selective cerebrocortical regions with high O2 extraction. However, the effect of sympathetic innervation on the heterogeneity of cerebrocortical venous O2 saturation was not potentiated by hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)
交感神经系统是增加大脑皮质静脉血氧饱和度异质性的因素之一，并且当颈交感神经活动增强时，这种异质性在缺氧期间会更大。32只雄性Long-Evans大鼠，一半进行假手术（n = 16），另一半接受双侧颈交感神经切除术（n = 16）。每种处理中的一半动物（n = 8）接受缺氧刺激（氮气中8%氧气）。用[14C]碘安替比林测定五个脑区的脑血流量。用显微分光光度法测量大脑皮质小动脉和静脉中的血氧饱和度。假手术组和交感神经切除组之间的缺氧性充血程度无显著差异。在常氧和缺氧条件下，假手术组中表明氧气供应与消耗平衡的皮质静脉血氧饱和度的异质性明显更大。常氧假手术动物的变异系数（CV = 100×标准差/平均值）为24.9%，平均静脉血氧饱和度为53.8%。缺氧期间，静脉血氧饱和度显著降至43.1%，而CV无变化（24.5%）。交感神经切除术通过减少常氧条件下低血氧饱和度静脉的数量显著降低了这种异质性（CV = 13.2%），缺氧条件下效果相似（CV = 15.3%）。在假手术组和交感神经切除组中，缺氧均引起大脑皮质氧气消耗显著增加。因此，双侧颈交感神经切除术改善了具有高氧提取率的选择性大脑皮质区域的氧气供应。然而，缺氧并未增强交感神经支配对大脑皮质静脉血氧饱和度异质性的影响。（摘要截断于250字）
