Ischemic preconditioning of the rat brain as a method of endothelial protection from ischemic/repercussion injury.

The studies reported here addressed the endothelium-protecting action of local and remote ischemic preconditioning of the brain in rats. Cerebral ischemia lasting 30 min was reproduced by thermocoagulation of the vertebral arteries with simultaneous clamping of the carotid arteries, the procedure being followed by reperfusion via the carotid arteries for 120 min (controls). The early and late phases of ischemic preconditioning and remote preconditioning were reproduced. Brain blood flow was recorded using high-frequency Doppler ultrasonography. The early and late phases of local ischemic preconditioning and the late phase of remote ischemic preconditioning were found to have endothelium-protecting actions apparent as improvements in the recovery of brain blood flow in the post-ischemic period in preconditioned rats, with lower levels of endothelial desquamation and cerebral edema. Blockade of nitric oxide synthesis eliminated the protective effects of both phases of preconditioning.