OBJECTIVETo observe the change of nitric oxide (NO) levels in the blood and the morphological change of the muscles in the limbs of rats during the (IR) injury and after being intervened by L-arginine (L-Arg) and L-nitroarginine (L-NNA).

METHODSSixty-six male Sprague-Dawley (SD) rats were used an d grouped into the normal controls, the sham injury controls, the IR injury group and the intervention groups (L-Arg group and L-NNA group). After 6 hours of ischemia, followed by reperfusion for 3, 12 or 24 hours, the samples in the IR injury group were obtained. The rats in the intervention groups were given L-Ar g (100 mmol/L) and L-NNA (10 mmol/L), respectively, through the abdominal cavity. Then the anterior tibial muscle in the right limb was obtained for histological examination, the anterior tibial muscle in the left limb for ultrastructure observation and the blood for assay of NO in all the rats. NO was assayed by indirect measurement of NO(2)(-)/NO(3)(-) with Griess method.

RESULTSThere was no significant difference of NO between the normal controls and the sham injury controls (P>0.05). But NO significantly decreased in the IR injury group (P<0.01), and further decreased with reperfusion (P<0.01) and reached the lowest point at 12 hours after reperfusion. The level of NO in the L-Arg group was significantly higher than that in the IR injury group ( P<0.01), but was not significantly different from that in the controls (P>0.05). In the L-NNA group, NO decreased to the undetectable level (P<0.01). Histological examination and ultrastructure observation showed the muscles were normal in the control groups. After 6 hours of ischemia, the skeletal muscles displayed injuries, and they were most severely injure d after 12 hours of reperfusion. In the L-Arg group, the skeletal muscles were less injured, while in the L-NNA group, the injury was similar to that in the I R injury group.

CONCLUSIONSWhen the limbs of the rats sustain IR, NO in the blood decreases. Meanwhile, the muscles in the limbs are injured. When L-Arg is given, NO in the blood is restored and the muscles are protected. When L-NNA completely inhibits NO, no protection of the muscles is shown.