ABSTRACT
Nitric oxide synthases (NOSs) that catalyzed the conversion of L-arginine to nitric oxide and L-citrulline play a role in ischemic-reperfusion injury. The purpose of this study was to observe the expression patterns of nNOS, iNOS and eNOS in the rat tibialis anterior and soleus muscles after multiple cyclic episodes of ischemic preconditioning (IP). Nine weeks old male SD rats were divided into control and IP groups. The IP group was further divided into 3 groups based on cycle of IP. For IP, left commom iliac artery was occluded 3, 6 and 10 times for 5 minutes ischemia followed by 5 minutes reperfusion using rodent vascular clamps. The animals were sacrificed at 0, 3, 6, 24 and 72 hours of reperfusion and the left tibialis anterior and soleus muscles were removed. The expression of nNOS, iNOS and eNOS were examined with immunohistochemical methods and Western blot analysis. IP increased the expression of nNOS, compared with the control. In the tibialis anterior muscle, the levels of nNOS in the 3IP and 6IP were higher than that in 10IP. IP increased the expression of iNOS, compared with the control, and the levels of iNOS in tibialis anterior muscle were higher than that in soleus muscle. The level of iNOS in the 10IP was higher than those in the 3IP and 6IP. IP increased the expression of eNOS, compared with the control, and the level of eNOS in soleus muscle were higher than that in tibialis anterior muscle. At 0 and 3 hours after reperfusion, the level of eNOS in 6IP and 10IP were higer than that in 3IP. In summary, these results suggest that the ischemic preconditioning increases the expression of nNOS, iNOS and eNOS, and 10 times of ischemic preconditioning may induce ischemic injury through upregulation of iNOS. And tibialis anterior muscle is more susceptabile to ischemic injury than soleus muscle.