The Effect of Inducible Nitric Oxide Synthase on Multiterritory Perforator Flap Survival in Rats.

Inducible nitric oxide synthase (iNOS) plays an important role in vasodilation, angiogenesis, and ischemia-reperfusion injury. We investigated the effects of iNOS on the survival and choke vessels of multiterritory perforator flaps in rats.  In this study, 84 rats were divided into two groups of 42 rats each and subjected to multiterritory perforator flap operations. Rats in group A received daily intraperitoneal doses of 100 mg per kg of aminoguanidine (AG) and rats in group B received daily intraperitoneal injections of the same volume of saline solution. On postoperative day 7, the surviving flap area was calculated as a percentage of the total flap dimensions using DP2-BSW software. The diameter and density of microvessels in the second choke zone of the flap were calculated from histology studies. The nitric oxide (NO) content was measured using NO concentration assay kits, and the levels of vascular endothelial growth factor (VEGF) and iNOS were assessed using western blotting. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were measured using test kits. Laser Doppler imaging was used to evaluate flap perfusion in the second choke zone for 7 days after surgery.  The flap survival area, diameter and density of microvessels, iNOS and VEGF levels, NO content, blood perfusion, and MDA content were significantly higher in the control group compared with the AG group, whereas SOD activity was significantly lower in the control group.  iNOS has a beneficial effect on the survival of multiterritory perforator flaps.