nitroarginine and Burns

Burn injuries trigger a pronounced inflammatory response in the burned skin, resulting in oedema formation and impaired circulation. This response involves activation of the nitric oxide (NO) synthetic pathway, which could play a key role in the complex hemodynamic and hemostatic changes occurring as a result of a burn trauma. The results presented in full-thickness skin burns of rats show that the NO-precursor, L-arginine (n = 10), inhibit burn-induced plasma extravasation as compared to saline-treated burned controls (n = 10) (p<0.001) to a level not significantly different from nonburned animals. Administration of the NO-synthase inhibitor. NG-nitro-L-arginine (L-NNA) (n = 10), did not significantly influence burn extravasation compared to burned controls. Accumulated urine volume 90 min post-burn increased ten-fold in burned animals treated with L-arginine compared to saline-treated burned controls (p<0.001) and nonburned animals (p<0.001), while L-NNA had no significant effect on diuresis. A significantly increased proteinuria occurred in L-arginine treated burned animals as compared to burned controls and nonburned controls (p<0.001), whereas L-NNA did not significantly influence the leakage of protein in the urine. Activation of NO synthesis significantly suppresses burn edema and strongly increases diuresis along with increased proteinuria.

Topics: Albumins; Animals; Arginine; Burns; Diuresis; Edema; Enzyme Inhibitors; Evans Blue; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Proteinuria; Rats; Rats, Sprague-Dawley; Spectrophotometry; Urine

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-L-arginine (L-NNA) (n = 6) nor the NO precursor, L-arginine, significantly influenced skin perfusion in nonburned skin compared to saline-treated animals. In the area of full-thickness skin burn, neither L-arginine (n = 6) nor L-NNA (n = 6) had significant influence on post-burn perfusion compared to saline-treated controls (n = 6). Administration of L-NNA (n = 6) significantly impaired skin perfusion in the area adjacent to the contact burn representing a partial-thickness burn, while the NO precursor, L-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 L-arginine may suggest that NO synthesis in response to the thermal trauma is already at a peak.

Topics: Animals; Arginine; Burns; Enzyme Inhibitors; Laser-Doppler Flowmetry; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Sprague-Dawley; Skin

To investigate cytoprotection against mucosal injuries of the stomach in patients with diabetes, we investigated gastric mucosal blood flow (GMBF), its response to a burn stress, and the involvement of nitric oxide (NO) in streptozotocin (STZ) diabetic rats. GMBF was measured by laser-Doppler velocimetry (LDV) and by the hydrogen gas clearance technique (HGC). The steady-state GMBF of STZ rats decreased according to the duration of diabetes, and insulin treatment blocked this decrease. Burn stress caused a rapid decrease in the GMBF. Reduction of the GMBF and gastric mucosal leakage of Evans blue (EB) after the burn stress were greater in the STZ rats than in the controls, but insulin treatment completely blocked this increase in EB leakage in the STZ rats. There was a significant negative correlation between the percent GMBF 3 h after the burn stress and EB leakage at the same time point. In the controls and the insulin-treated STZ rats, N-nitro-L-arginine (L-NNA), an NO synthase inhibitor, enhanced the decrease in postburn GMBF and EB leakage, but was without effect in the STZ rats. These results suggest that NO may be involved in the regulation of GMBF, and that persistent hyperglycemia may impair this regulation. These findings suggest that patients with diabetes have reduced cytoprotection against a variety of gastric mucosal injuries.

Topics: Animals; Burns; Capillary Permeability; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Gastric Mucosa; Insulin; Male; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Rats; Rats, Wistar; Regional Blood Flow; Streptozocin; Stress, Physiological; Time Factors