| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Akira School of Medicine, Hamamatsu University School of Medicine, Instructor, 医学部, 助手 (30322142)
IWAMOTO Tatsuaki University Hospirtaly, Hamamatsu University School of Medicine, Instructor, 医学部・附属病院, 助手 (70303568)
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| Research Abstract |
Nitric oxide (NO) donors have been shown to be protective against hemorrhagic shock (HS). Sixty min afterHS (MAP : 40 mmHg), the animals were treated with saline or S-niotroso-N-acetylpenicillamine (SNAP) ; 5 μg/kg/10 min followed by 5 μg/kg/h (SNAP-Gr). After another 60 min, the shed blood was reinfused. Reactivities to noradrenalin (NA), changes in hemodynamics, the plasma catecholamines, and NO derivatives were determined. In Cont-Gr, 3 dogs died at 90, 98, and 102 min after HS.In Cont-Gr, % changes of systolic ABP to 1 and 2.5 μg/kg of NA after the recovery from HS decreased from 23.7±4.1 % (before HS) to 6.5±0.6 and from 50.1±7.7 % (before HS) to 14.5±2.6, respectively (p<0.01). In SNAP-Gr, reactivity to NA was maintained. At 120 min after HS (HS-120), MAP and CO in SNAP-Gr increased but not in Cont-Gr. Plasma CA levels in SNAP-Gr were suppressed compared to those of Cont-Gr. In conclusion, a small dose of SNAP during HS improved the mortality of the dogs. This might have been due
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in part to the remaining vascular hyporeactivity.
Then, we evaluated the effects of inspiratory oxygen concentration on a model of HS in rats. Twenty-eight male rats, randomly divided into four groups according to the ventilation method and oxygen concentration : mechanical ventilation with pure oxygen (M100) ; mechanical ventilation with air (M21) ; spontaneous respiration with pure oxygen (S100) ; and spontaneous respiration with air (S21). MAP was maintained at 40-50 mmHg for 2h. After the HS, the blood remaining in the reservoir was reinfused. Then survival rate and MAP were monitored for 2h. During HS, the survival rate of the S21 group was lower than that of the M100 and S100 groups (p<.05). Before HS, MAP of M100 and S100 groups were significantly higherthan those of M21 and S21 groups (p<.05). In the M100 and M21 groups, MAP at 2 hr after reinfusion were significantly lower than the baseline value (p<.05). Before HS, reactivity to NE of the M21 group was significantly higher than that of the other groups (p<.05). In the M21 group, reactivity to NE after HS was significantly lower than it was before HS (p<.05). Respiration with oxygen is needed in hemorrhagic shock studies that discuss survival rate. Mechanical ventilation disturbed the compensatory hyperventilation. We must also pay attention to the effects of mechanical ventilation on the circulatory. Less
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