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Beneficial effect of hyperbaric oxygen pretreatment on lipopolysaccharide‐induced shock in rats
Author(s) -
Pedoto Alessia,
Nandi Jyotirmoy,
Yang Zhongjin,
Wang Jingping,
Bosco Gerardo,
Oler Albert,
Hakim Tawfic S,
Camporesi Enrico M
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2003.03865.x
Subject(s) - chemistry , lipopolysaccharide , nitric oxide , saline , myeloperoxidase , nitric oxide synthase , arterial blood , pharmacology , anesthesia , endocrinology , medicine , inflammation , organic chemistry
Summary 1. We investigated the effect of hyperbaric oxygenation (HBO 2 ) pretreatment on the production of exhaled nitric oxide (ENO) and the expression of lung inducible nitric oxide synthase (iNOS) by Escherichia coli lipopolysaccharide (LPS)‐induced shock in an experimental rat model. 2. Rats were randomized into four groups, anaesthetized, mechanically ventilated with room air and infused with normal saline (2 mL/h) through the jugular vein for 5 h. Group 1 (NS) received only normal saline. Group 2 (HBO 2 ‐NS) was pretreated with HBO 2 at 2.8 absolute atmospheres for 2 h and then received normal saline. Group 3 (LPS) received LPS, 20 mg/kg, i.v., bolus. Group 4 (HBO 2 ‐LPS) was pretreated with HBO 2 for 2 h, followed by LPS. 3. Arterial blood gases, blood pressure, blood pH and ENO production were measured every 30 min. Plasma nitrite/nitrate (NO x ) concentrations were assessed at the beginning (baseline) and at the end of the study. Lung myeloperoxidase (MPO) activity, iNOS expression and histological scores were measured for the evaluation of lung injury. 4. Administration of LPS was associated with decreased blood pressure and pH, increased ENO production, plasma NO x concentrations, lung iNOS expression and MPO activity. 5. Pretreatment with HBO 2 significantly alleviated the LPS‐induced hypotension, acidosis and decreased ENO production, plasma NO x concentrations, lung MPO activity and expression of iNOS. Hyperbaric O 2 had no effect on control rats. 6. Our data show that HBO 2 pretreatment has beneficial haemodynamic effects in rats with endotoxin shock. The beneficial effects of HBO 2 may be partially mediated by decreased ENO production via reduced LPS‐induced lung iNOS expression.