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출혈성 Shock에 관한 연구

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 Experimental studies on hemorrhagic shock 
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[영문] Part Ⅰ. Hemorrhagic Shock and Cardiac Catecholamines It is generally known that vasoconstriction is a prominent feature of the early stage of hemorrhagic shock in experimental animals, and that this is a protective mechanism mediated through the sympathetic nervous system to maintain a blood supply to vital organs. Freeman et al.(1938), however, pointed out that, although animals with intact sympathetic nervous system were able to compensate more readily to acute hemorrhage than completely sympathectomized animals, the mortality rate was greater in intact than in sympathectemized animals if the hemorrhagic hypotension was prolonged. This concept was supported by many other workers (Gope, 1911; Pillcher et al., 1914; Bayliss, 1923). Furthermore, it has also been shown that the adrenergic blocking agent such as dibenamine can protect from the lethal effects of hemorrhagic hypotension (Wiggers et al., 1950;Levy et al., 1954; Lillehei et al., 1964). These observations lead to the proposal that decrease in sympathetic nervous system response might be pertinent for a decrease in mortality following hemorrhagic shock. In contrast to the above reports, Chien and Hitzig (1960) determined the amount of blood withdrawal which produced death in 50% of intact and sympathectomized dogs and concluded that the presence of the sympathetic nervous system increased the tolerance to hemorrhage shock. Although there is controversial reports concerning the effects of sympathetic nervous system on hemorrhagic shock, it is obvious that the adrenergic neurotransmitter, i.e. catecholamines play an important role in the lethal effects of hemorrhage. In addition, Park(1961) demonstrated that myocardial catecholamines were significantly reduced during hemorrhagic hypotension. Coleman and Glaviano(1963) also showed that catecholamines in the heart, spleen, brain, and liver were markedly decreased during relationship between the endogenous tissue catecholamines and hemorrhagic shock. The present experiment, therefore, was designed to explore the role of cardiac catecholamines in the mortality of hemorrhagic shock. Healthy albino male rabbits, weighing approximately 2.0kg, were anesthetized with urethane (0.4g/kg) given intravenously. A carotid artery was exposed and was directly connected to a mercury manometer for continuous recording of changes in arterial blood pressure on smoked drum. The other carotid artery was also exposed in order to withdraw blood. Endotracheal intubation was employed so that a free air-way maintained at all times and heparin (3.0-5.0mg/kg) was injected intravenously to prevent blood coagulation. Initial 10.0ml of blood per kg of animal weight was rapidly withdrawn and thereafter 2.0ml/kg of blood was withdrawn at an interval of 10 minutes until the animal died. 1. Following the initial bleeding of 10.0ml/kg in normal rabbits, the mean arterial pressure was rapidly dropped to 60mmHg from 110mmHg. Thereafter, the blood pressure was gradually reduced until death. The average survival time and total bleeding volume for these animals were 84 minutes and 28.0ml/kg, respectively. Examination of the cardiac catecholamines soon after death revealed average 1.18μg/g, which is significantly smaller than that of normal(1.68μg/kg). 2. The injection of norepinephrine (2.0mg/kg) markedly elevated the concentration of myocardial catecholamines in rabbits. At the end of one hour after injection of norepinephrine, the animals were subjected to hemorrhagic shock by the procedure described previously. The average survival time for these animals was 62minutes, indicating that pretreatment of norepinephrine hasten the death due to hemorrhagic shock. The average bleeding volume was 18.0ml/kg and the cardiac catecholamine concentration was 1.21μg/g which is not significantly different from the control animals. 3. The intraperitoneal injection of reserpine (3.0mg/kg) depletes almost completely the cardiac catecholamines of rabbits within 24 hours. At the end of 24 hours after the injection of reserpine, the animals were subjected to hemorrhagic shock. The total bleeding volume taken until death was 30.0ml/kg. The average survival time for those rabbits was 101 minutes which is significantly longer than that observed in control animals.
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2. Thesis / Dissertation (학위논문) > 1. College of Medicine (의과대학) > Ph.D. (박사)
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