C57B6 mice were subjected to 50 % proximal SBR or a sham procedure. Photoacoustic microscopy (PAM) was used to measure blood flow and sO2 on postoperative days (PODs) 1, 3, and 7. Ileal tissue was harvested 6 h postoperatively and on PODs 1 and 2, and HIF1¦Á, HIF2¦Á, and VEGF mRNA expression were assessed via RT-PCR. A p value of less than 0.05 was considered significant.
Following SBR, reduction in intestinal blood flow persists for 24 h and is followed with hyperemia by POD 3. The immediate reduction in venous sO2 and increased tissue oxygen utilization continued through POD 7. Enhanced expression of HIF1¦Á was demonstrated 6 h following SBR.
Massive SBR results in an immediate relative hypoxic state within the remnant bowel with early enhanced expression of HIF1¦Á. On POD 7, increased tissue oxygen extraction and elevated blood flow persist in the adapting intestine.