The protective role of nitric oxide and nitric oxide synthases in whole-body hyperthermia-induced hepatic injury in rats.
OBJECTIVE
The present study was designed to elucidate the role of endothelial nitric oxide (NO) synthase (eNOS), inducible NOS (iNOS)-derived NO and heat-shock protein (Hsp70) in a rat model of whole-body hyperthermia (WBH)-induced liver injury.


METHODS
Real-time polymerase chain reaction, immunohistochemistry and western blot were used to observe the mRNA and protein expression of eNOS, iNOS and Hsp70. Rats were exposed to hyperthermia by immersion for 60 min at a conscious state in a water bath maintained at 41°C. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were used to assess liver injury 15 h after the hyperthermia challenge. Nitrosative and oxidative mediators, particularly NO and hydroxyl radical were measured.


RESULTS
Plasma AST, ALT, hydroxyl radical, and NO were significantly increased after WBH. There were 4.14 ± 0.42, 2.82 ± 0.34 and 2.91 ± 0.16-fold increases in the mRNA expression of eNOS, iNOS and Hsp70. Immunohistochemistry and western blot showed up-regulation of eNOS, iNOS and Hsp70 protein. An eNOS inhibitor (N(ω)-nitro-L-arginine methyl ester (L-NAME)), or an iNOS inhibitor (aminoguanidine (AG)), significantly aggravated the liver injury. On the contrary, administration of NO precursor, L-arginine (L-ARG), attenuated the liver injury. Hsp70 inhibitor quercetin reduced Hsp70, while aggravating the WBH-induced hepatic changes.


CONCLUSIONS
WBH induces increases in eNOS, iNOS and Hsp70 expression with increase in NO release. The deleterious effects of L-NAME and AG and the protective effects of L-ARG and Hsp70 inhibitor on the liver function and pathology suggest that NO and heat shock protein play a beneficial role in the WBH-induced hepatic injury.
Division of Gastroenterology, Department of Internal Medicine, Cheng Hsin General Hospital, Taipei, Taiwan.
Chao-Fuh
CF
Chen
David
D
Wang
Fur-Jiang
FJ
Leu
Hsing I
HI
Chen
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006979:Hyperthermia, Induced / Q000009:adverse effects*; D008107:Liver Diseases / Q000209:etiology / Q000378:metabolism*; D008297:Male; D008760:Methylguanidine / Q000097:blood; D009566:Nitrates / Q000097:blood; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009573:Nitrites / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley
D018840:HSP70 Heat-Shock Proteins; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D008760:Methylguanidine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase