Increased nitric oxide synthase activity is essential for electromagnetic-pulse-induced blood-retinal barrier breakdown in vivo.
OBJECTIVE
To examine whether electromagnetic pulses (EMPs) affected the permeability of the blood-retinal barrier (BRB), gene expression of occludin and activity of nitric oxide synthase (NOS).


METHODS
Sprague-Dawley (SD) rats were used and randomized into EMP and control groups. Retinas were removed immediately, and 2 h or 24 h after EMP radiation. BRB permeability was analyzed by transmission electron microscopy and Evans Blue staining. Retinal NOS activity and concentrations of nitrite and nitrate were measured. Occludin mRNA and protein levels were detected by RT-PCR and Western blotting.


RESULTS
Exposure of SD rats to EMP resulted in increased BRB permeability, with the greatest decrease in occludin at 24 h. Moreover, this permeability defect was also correlated with significant increases in the formation of NO and induction of NOS activity in SD rats. Furthermore, we found that treatment with NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) blocked BRB breakdown and prevented the increase in NO formation and induction of NOS activity, as well as the decrease in occluding expression.


CONCLUSIONS
Taken together, these results support the view that NOS-dependent NO production is an important factor that contributes to EMP-induced BRB dysfunction, and suggests that NOS induction may play an important role in BRB breakdown.
Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China. lulianj@fmmu.edu.cn
Lianjun
L
Lu
Hui
H
Xu
Xiaowu
X
Wang
Guozhen
G
Guo
D000704:Analysis of Variance; D000818:Animals; D001813:Blood-Retinal Barrier / Q000378:metabolism* / Q000528:radiation effects*; D015153:Blotting, Western; D005070:Evans Blue; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D062793:Occludin; D010539:Permeability / Q000528:radiation effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D008565:Membrane Proteins; D009566:Nitrates; D009573:Nitrites; D062793:Occludin; C568987:Ocln protein, rat; D012333:RNA, Messenger; D005070:Evans Blue; D019001:Nitric Oxide Synthase