Role of nitric oxide in the control of burn perfusion

Vascular changes following deep skin burns are characterised by vasoconstriction and progressive ischemia. Nitric oxide (NO) has been shown to be a potent regulator of vascular smooth muscle tone and tissue perfusion. We assessed the importance of NO on post-burn skin perfusion in rats using laser Doppler. The present results show that neither the NO-synthase inhibitor, NG-nitro- -arginine ( -NNA) (n=6) nor the NO precursor, -arginine, significantly influenced skin perfusion in nonburned skin compared to saline-treated animals. In the area of full-thickness skin burn, neither -arginine (n=6) nor -NNA (n=6) had significant influence on post-burn perfusion compared to saline-treated controls (n=6). Administration of -NNA (n=6) significantly impaired skin perfusion in the area adjacent to the contact burn representing a partial-thickness burn, while the NO precursor, -arginine (n=6) had no significant effect on burn perfusion as compared to saline-treated controls (n=6). In conclusion, impairment of perfusion in a full thickness burn following administration of NO-synthase inhibitor suggests that nitric oxide is involved in the mechanisms responsible for maintaining adequate circulation post-burn. The lack of additional improvement of perfusion in response to -arginine may suggest that NO synthesis in response to the thermal trauma is already at a peak.