Acute remote ischemic preconditioning on a rat cremasteric muscle flap model

A previous study showed, in a rat adipocutaneous flap model, that acute ischemic preconditioning (IP) can be achieved not only by preclamping of the flap pedicle, but also by a brief extremity ischemia prior to flap ischemia. The purpose of this study was to determine whether remote IP is also effective in other tissues such as muscle flaps. Twenty male Wistar rats were divided into three experimental groups. The rat cremaster flap in vivo microscopy model was used for assessment of ischemia/reperfusion injury. In the control group (CG, n = 8), a 2-hr flap ischemia was induced after preparation of the cremaster muscle. In the "classic" IP group (cIP, n = 6), a brief flap ischemia of 10 min was induced by preclamping the pedicle, followed by 30 min of reperfusion. A 10-min ischemia of the contralateral hindlimb was induced in the remote IP group (rIP, n = 6). The limb was then reperfused for 30 min. Flap ischemia and the further experiment were performed as in the CG. In vivo microscopy was performed after 1 hr of flap reperfusion in each animal. A significantly higher red blood cell velocity in the first-order arterioles and capillaries, a higher capillary flow, and a decreased number of leukocytes adhering to the endothelium of the postcapillary venules were observed in both preconditioned groups by comparison to the control group (P < 0.05). The differences within the preconditioned groups were not significant for these parameters. Our data show that ischemic preconditioning and improvement of flap microcirculation can be achieved not only by preclamping of the flap pedicle, but also by induction of an ischemia/reperfusion event in a body area distant from the flap prior to elevation. These findings indicate that remote IP is a systemic phenomenon, leading to an enhancement of flap survival. Our data suggest that remote IP could be performed simultaneously with flap elevation in the clinical setting without prolongation of the operation and without invasive means.