The role of ischemic preconditioning at the gracilis muscle of rats in the early phase of reperfusion injury.
OBJECTIVE
Verify the role of ischemic preconditioning (IPC) in ischemia and reperfusion injury on gracilis muscle of rats.


METHODS
Wistar rats (n=30) were distributed in three groups, I/R and IPC groups were subdivided concerning ischemia time. A near-amputation model of the posterior limb was produced by a hip joint level incision, preserving the vascular bundle and the femur bone and ischemia was induced for 2 h and 4 h, G-I 2 h/R (n=6) and G-I 4 h/R (n=6), followed by 1 h of vascular reperfusion. The preconditioned groups, G-PCI 2 h (n=6) and G-PCI 4 h (n=6), were preceded by 3 cycles of 5 min of ischemia followed by 5 min of vascular reperfusion before sustained ischemia. In the Control Group, C-G (n=6) animals were subjected to regional approach. The analysis was done with Light Microscopy (LM).


RESULTS
The levels of fibril fragmentation were progressive in the G-I 2 h/R (67% of muscle preservation) and in the G-I 4 h/R (0% of muscle preservation). However in the group of the precondition the lesion degree being in level similar to the group controls in the G-I 2 h/R (100% of muscle preservation) while at G-I 4 h/r occur less protection (67% of muscle preservation). The degree of tissue inflammatory reaction was worst at G-I 4 h/R (0% without inflammation signals) than at G-I 2 h/R (50% without inflammation signals); while in the precondition group G-IPC-2 h (83% without inflammation signals) was better than the G-IPC-4 h (67% without inflammation signals). The vascular stasis was absent only in 17% of the G-I 4 h/R and in 33% of the G-I 2 h/R. In precondition group, however, the vascular stasis was absent in 33% at G-IPC 2 h and absent in 50% at G-IPC 4 h.


CONCLUSIONS
The IPC showed, in an earlier phase, a beneficial role at I/R derived injury on gracilis muscle of rats, as proven for the largest preservation of the fibers muscular, smaller inflammatory reaction and smaller vascular stasis.
Federal University of São Paulo, UNIFESP, EPM, São Paulo, Brazil. rswebster@turbo.com.br
Ronaldo Scholze
RS
Webster
Edna Frasson Souza
EF
Montero
Djalma José
DJ
Fagundes
Cláudio Galleano
CG
Zettler
José
J
Coiro
D000818:Animals; D007249:Inflammation / Q000503:physiopathology; D019194:Ischemic Preconditioning; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*; D013848:Thigh