Endotoxin-induced acute lung injury is enhanced in rats with spontaneous hypertension.
1. Acute lung injury (ALI), or acute respiratory distress syndrome, is a major cause of mortality in endotoxaemia. The present study tested whether the endotoxaemia-induced changes and associated ALI were enhanced in rats with established hypertension and to examine the possible mechanisms involved. 2. Fifty spontaneously hypertensive rats (SHR) and the same number of normotensive Wistar Kyoto (WKY) rats, aged 12-15 weeks, were used. The experiments were performed in conscious, unanaesthetized rats. Endotoxaemia was produced by intravenous lipopolysaccharide (LPS; 10 mg/kg). N(G)-Nitro-L-arginine methyl ester (L-NAME; 10 mg/kg, i.v.), L-N(6)-(1-iminoethyl)-lysine (L-Nil; 5 mg/kg, i.v.) and 3-morpholinosydnonimine (SIN-1; 5 mg/kg, i.v.) were given 5 min before LPS to observe the effects of nitric oxide synthase (NOS) inhibition and nitric oxide (NO) donation. 3. We monitored arterial pressure and heart rate and evaluated ALI by determining the lung weight/bodyweight ratio, lung weight gain, leakage of Evans blue dye, the protein concentration in bronchoalveolar lavage and histopathological examination. Plasma nitrate/nitrite, methyl guanidine, pro-inflammatory cytokines, including tumour necrosis factor-alpha and interleukin-1beta, and lung tissue cGMP were determined. Expression of mRNA for inducible and endothelial NOS was examined using reverse transcription-polymerase chain reaction. 4. Lipopolysaccharide caused systemic hypotension, ALI and increases in plasma nitrate/nitrite, methyl guanidine, pro-inflammatory cytokines and lung cGMP content. The LPS-induced changes were greater in SHR than in WKY rats. Pretreatment with L-NAME or L-Nil attenuated, whereas the NO donor SIN-1 aggravated, the endotoxin-induced changes. 5. In conclusion, rats with genetic hypertension are more susceptible to endotoxaemia and this results in a greater extent of ALI compared with normotensive WKY rats.
Liu
Demeral D
DD
Department of Dentistry, Tzu Chi Hospital and University Hualien, Taiwan.
Hsu
Yung Hsiang
YH
Chen
Hsing I
HI
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D006152:Cyclic GMP / Q000378:metabolism; D019446:Endotoxemia / Q000378:metabolism / Q000473:pathology; D006973:Hypertension / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D053583:Interleukin-1beta / Q000097:blood; D008070:Lipopolysaccharides; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008760:Methylguanidine / Q000097:blood; D009566:Nitrates / Q000097:blood; D052247:Nitric Oxide Synthase Type II / Q000235:genetics; D052250:Nitric Oxide Synthase Type III / Q000235:genetics; D009573:Nitrites / Q000097:blood; D009929:Organ Size / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D009566:Nitrates; D009573:Nitrites; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D008760:Methylguanidine; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat; D006152:Cyclic GMP