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Abstract
Ischemia reperfusion injury is an area which has received considerable attention in the past decade because of its direct clinical relevance. (1) A number of drugs appear to mimic ischemic preconditioning. This phenomenon “pharmacological preconditioning” has been demonstrated with nicorandil,opioid receptor agonists and volatile anaesthetics.(2) A variety of mechanisms have been discussed to explain the beneficial role of pharmacological preconditioning; however, the exact underlying mechanisms of protection are still unknown.(2) During the short preconditioning period of ischemia; several trigger substances are released (adenosine, bradykinin, norepinephrine, opioids). By activation of membrane- bound receptors, these substances activate a complex intracellular signaling cascade, which converges on mitochondrial end-effectors . Activation of this pathway protects the cells against both necrosis and apoptosis during a subsequent more prolonged ischemic episode.
Several studies have documented that anesthetics including isoflurane and propofol have a pharmacological preconditioning effect in the heart , brain , kidney , lung , cultured rat smooth muscles and human endothelial cells. (4-9) However ,the effect of isoflurane and propofol on skeletal muscle ischemia reperfusion injury induced by the use of arterial tourniquet is not clear. The study was carried out in Menoufiya University Hospital on 60 adult patients undergoing lower limb operations involving the use of a pneumatic tourniquet. All patients were thoroughly evaluated and investigated to ensure that they were ASA I or II physical status after informed consent were obtained from all patients.