Different intervals of ischemic preconditioning on small bowel ischemia-reperfusion injury in rats.

PURPOSE: The purpose of this study was to establish morphologically the best time of vascular occlusion to induce ischemic preconditioning (IPC) for rat small bowel undergoing ischemia and reperfusion injury. METHODS: After approval by the Ethics Committee, 36 EPM-1 young adult Wistar rats from 300-350 g were distributed into 6 groups: sham (S); ischemia and reperfusion (IR), with 50 minutes of cranial mesenteric artery occlusion and 30 minutes of reperfusion; IPC with 1 cycle of 2 minutes (IPC-2), 5 minutes (IPC-5), 10 minutes (IPC-10), or 15 minutes (IPC-15), followed by sustained IR. The animals anesthetized with ketamine (60 mg/kg) and xylazine (10 mg/kg) intramuscular (IM), were maintained on mattress heat, hydrated with saline (80 mL/kg), and injected with 100 IU heparin. Samples of jejunum were stained with hematoxylin and eosin (HE) and classified according to Park et al. Statistical analysis of results was performed using Kruskal-Wallis tests (P < .05). RESULTS: The histological evaluation showed no difference between IR and IPC15 rats (5.2 and 5, respectively; P = .84). Greater jejunal injury was observed with IPC15 (5) compared with other groups (IPC2 = 3, P = .03; IPC5 = 3.2, P = .05; IPC10 = 2.8, P = .02, respectively). There was no difference between groups IPC2 x IPC5 x IPC10. CONCLUSION: Morphologically, IPC with short times promoted greater intestinal protection against the IR lesion in rats.

Remote ischemic preconditioning on neovascularization and follicle viability on ovary autotransplantation in rats.

PURPOSE: Verify the optimum remote vascular occlusion time to reduce ovarian injury in autologous transplants in rats. METHODS: Twenty-four adult female rats were assigned to four groups: GC (control group): bilateral oophorectomy followed by ovary transplant; GIPC (ischemic preconditioning group): remote ischemic preconditioning at the iliac artery for 5, 10, and 15 minutes (GIPC-5, GIPC-20, and GIPC-15) previous to bilateral oophorectomy and ovarian transplantation. The right ovary was fixed in the retroperitoneum. Euthanasia was performed 4 days after the surgical procedure. The follicles were counted and classified as developing versus atretic. The immunohistochemical assay identified vascular factor of endothelial growth (VEGF) in the ovarian stroma and assessed the proliferation capacity by means of the Ki-67 in the ovarian follicles. RESULTS: Every group showed an inflammatory infiltrate, luteous body, and ovarian follicles in several phases of development. The ischemic preconditioning groups displayed greater amounts of viable ovarian follicles and increased vascularization and vasodilatation than the control group. GIPC-15 showed the highest amount of viable follicles compared to the others (P < .05 GIPC-15 vs GC; GIPC-15 vs GIPC-5). More VEGF-labeled cells were observed in GIPC-10 than the control group (P < .05, GIPC-10 vs GC). The proliferation index assessed by Ki-67 marking showed GC: 80%; GIPC-5: 76%; GIPC-10: 67%; and GIPC-15: 64% (P > .05). CONCLUSIONS: The PCI-15 cohort seem to be the most adequate timing to achieve functional support and preservation of a greater number of viable ovarian follicles.