Abstract 2487: Ischemia/Reperfusion Injury Impairs Myogenic Tone of Cerebral Vessels in both Ischemic and Nonischemic Hemispheres: Differential Role of Oxidative Stress.
Cerebrovascular autoregulation and reactivity are critical to maintain constant perfusion during ischemic brain injury. It is known that ischemia/ reperfusion (I/R) injury and resulting oxidative stress impair vessel reactivity in ischemic hemisphere. Yet the behavior of vessels in nonischemic hemisphere is still unexplored.
Hypothesis: I/R injury impairs myogenic tone of vessels in both ischemic and nonischemic hemispheres via increased peroxynitrite (ONOO-) generation.
Methods: Middle cerebral arteries (MCA) isolated from age matched male Wistar rats (n=6) subjected to 30 min MCA occlusion (MCAO)/45 min reperfusion, or MCAO followed by treatment with ONOO- scavenger FeTPPs (20mg/kg) at reperfusion were pressurized in arteriograph chamber. In another set of animals, MCA isolated from control Wistar rats were exposed to ex vivo oxygen-glucose deprivation (OGD) then their myogenic tones across the pressure range were determined.
Results: I/R injury impaired myogenic tone of vessels in both ischemic and nonischemic sides albeit to a different degree. Interestingly FeTPPs restored myogenic tone of vessels from ischemic side only (Table). Vessels exposed to ex vivo and in vivo hypoxia experienced loss of myogenic tone. The reduction of myogenic tone % by OGD is similar to I/R injury.
Conclusion: Our ex vivo model of hypoxia is a valuable method to assess the ischemic insult on vessel reactivity. Increased ONOO- production is one of the underlying mechanisms of loss of tone under I/R injury in ischemic hemisphere, but the impairment of myogenic tone in nonischemic hemisphere involves other mechanisms. Understanding how I/R alters myogenic tone and ultimately cerebral perfusion in both ischemic and nonischemic hemispheres is vital in improving current preventive and therapeutic strategies for acute stroke. +p<0.001, *p< 0.05 vs Sham, # p<0.001 vs ischemic MCA ,**p<0.01 vs nonischemic MCA
- © 2012 by American Heart Association, Inc.