SYMPATHETIC-NERVES REDUCE CEREBRAL BLOOD-FLOW DURING HYPOXIA IN AWAKE RABBITS
SYMPATHETIC-NERVES REDUCE CEREBRAL BLOOD-FLOW DURING HYPOXIA IN AWAKE RABBITS
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DOI：
10.1152/ajpheart.1984.247.3.h446
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发表时间：
1984-01-01
影响因子：
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通讯作者：
BUSIJA, DW
中科院分区：
文献类型：
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作者：
BUSIJA, DW
以清醒兔为实验对象，观察了常氧和低氧复合失血性低血压时交感神经对脑血流量的影响。切除一侧颈上神经节，另一侧行假手术。5只兔暴露于常氧[动脉血氧分压(PaO2)·gtoreq]。78 mm Hg]或低氧(PaO2·ltoreq.39毫米汞柱)。每组用15微米微球测量脑血流量(BF)3次：正常血压[平均动脉压(MAP)80~86 mm Hg]、中度低血压(MAP 62~65 mm Hg)和重度低血压(MAP 49~50 mm Hg)。常氧状态下，流向大脑的血流量为70.+-。8(SE)毫升.cntdo.Min-1.cntdo.100g~(-1)，降压时无下降。交感神经在常氧状态下对脑血流量无影响。缺氧时，流向大脑的血流量为243.+-。21毫升.cntdot。Min-1.cntdo.正常血压时为100g-1，随动脉压降低而下降。在正常血压期间，流向失神经大脑的血流量高于健侧(13。+-。4%)，中度低血压(11.+-)。5%)和严重低血压(12.+-)。4%)。同样，去神经皮质灰质的血流量在正常血压期间更高(19。+-。4%)，中度低血压(16.+-)。6%)和严重低血压(17.+-)。6%)，与神经支配侧比较。重度低血压时，失神经小脑的血流量高于神经支配侧(27.0±-)。17%)。交感神经的反射激活减少了脑血流量，但不是常氧，交感神经的作用不依赖于大脑和皮质灰质的动脉压水平，但在小脑低血压时表现得更大。清醒兔在低氧状态下大脑自我调节功能丧失。
Effects of sympathetic nerves on cerebral blood flow (CBF) during normoxia or hypoxia combined with hemorrhagic hypotension were examined in awake rabbits. One superior cervical ganglion was excised and sham surgery was performed on the other side. Five rabbits each were exposed to normoxia [arterial O2 tension (PaO2) .gtoreq. 78 mm Hg] or hypoxia (PaO2 .ltoreq. 39 mm Hg). Cerebral blood flow (BF) was measured with 15-.mu.m microspheres 3 times in each group: normotension [mean arterial pressure (MAP) 80-86 mm Hg]; moderate hypotension (MAP 62-65 mm Hg) and severe hypotension (MAP 49-50 mm Hg). During normoxia, blood flow to cerebrum was 70 .+-. 8 (SE) ml .cntdot. min-1 .cntdot. 100 g-1 during normotension and did not decrease during hypotension. Sympathetic nerves had no effect on CBF during normoxia. During hypoxia, blood flow to cerebrum was 243 .+-. 21 ml .cntdot. min-1 .cntdot. 100 g-1 during normotension and fell as arterial pressure was lowered. Blood flow to denervated cerebrum was higher than on the intact side during normotension (13 .+-. 4%), moderate hypotension (11 .+-. 5%) and severe hypotension (12 .+-. 4%). Similarly, blood flow to denervated cortical gray matter was higher during normotension (19 .+-. 4%), moderate hypotension (16 .+-. 6%) and severe hypotension (17 .+-. 6%) when compared with the innervated side. Blood flow to denervated cerebellum was higher than the innervated side during severe hypotension (27 .+-. 17%). Reflex activation of sympathetic nerves reduces CBF during hypoxia but not normoxia, and sympathetic effects are not dependent on levels of arterial pressure in cerebrum and cortical gray matter, but appear to be greater during hypotension in cerebellum. Cerebral autoregulation is abolished during hypoxia in awake rabbits.