Jackman Katherine, Iadecola Costantino
Brain and Mind Research Institute, Weill Cornell Medical College , New York, New York.
Antioxid Redox Signal. 2015 Jan 10;22(2):149-60. doi: 10.1089/ars.2013.5669.
The brain has high energetic requirements and is therefore highly dependent on adequate cerebral blood supply. To compensate for dangerous fluctuations in cerebral perfusion, the circulation of the brain has evolved intrinsic safeguarding measures.
The vascular network of the brain incorporates a high degree of redundancy, allowing the redirection and redistribution of blood flow in the event of vascular occlusion. Furthermore, active responses such as cerebral autoregulation, which acts to maintain constant cerebral blood flow in response to changing blood pressure, and functional hyperemia, which couples blood supply with synaptic activity, allow the brain to maintain adequate cerebral perfusion in the face of varying supply or demand. In the presence of stroke risk factors, such as hypertension and diabetes, these protective processes are impaired and the susceptibility of the brain to ischemic injury is increased. One potential mechanism for the increased injury is that collateral flow arising from the normally perfused brain and supplying blood flow to the ischemic region is suppressed, resulting in more severe ischemia.
Approaches to support collateral flow may ameliorate the outcome of focal cerebral ischemia by rescuing cerebral perfusion in potentially viable regions of the ischemic territory.
大脑对能量需求很高，因此高度依赖充足的脑供血。为了补偿脑灌注的危险波动，脑循环进化出了内在的保护机制。
脑的血管网络具有高度冗余性，在血管闭塞时允许血流重新定向和重新分配。此外，诸如脑自动调节（其作用是在血压变化时维持恒定的脑血流量）和功能性充血（将血液供应与突触活动相耦合）等主动反应，使大脑能够在供应或需求变化的情况下维持充足的脑灌注。在存在高血压和糖尿病等中风危险因素的情况下，这些保护过程会受到损害，大脑对缺血性损伤的易感性会增加。损伤增加的一个潜在机制是，由正常灌注的脑产生并向缺血区域供血的侧支血流受到抑制，导致更严重的缺血。
支持侧支血流的方法可能通过挽救缺血区域潜在存活区域的脑灌注来改善局灶性脑缺血的结果。
