RESUMEN
<p><b>OBJECTIVE</b>To investigate the changes of nitric oxide concentration in the distal portion of a random pattern skin flap and the influence of the exogenous L-arginine on the survival of the random pattern skin flap.</p><p><b>METHODS</b>A random pattern skin flap (7 cm x 2 cm) was cranially designed and elevated on the back of a Wistar rat. An image analysis technology was used to evaluate the survival rate of the skin flap, while a biochemistry method was used to test the concentrations of the NO in the tissue.</p><p><b>RESULTS</b>The survival area of the flap in the L-arginine-treated group was significantly enlarged (63.83 +/- 5.13)% (P < 0.01) in seven days postoperatively, compared with the control group (43.26 +/- 2.86)%. The NO concentration in the tissue was no statistic difference between all of the groups immediately after the operation (P > 0.05). But, the NO concentration in the control was decreasing at the beginning and then increasing slightly to reach the high level in 12 hours after the operation. It was thereafter slumped down to the baseline in 72 hours after the surgery. Although the changes in the L-arginine-treated group were quite similar to the control excepting of the extent, the NO concentration was kept in a higher level in the sequential time after the operation (P < 0.01, P < 0.01, P < 0.05 and P < 0.01).</p><p><b>CONCLUSIONS</b>The NO concentration in skin flap tissue after the elevation was going up slightly for a short time. The exogenous L-arginine could promote the NO concentration in the random pattern skin flap to protect it from ischemic injury.</p>