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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During short-lasting hypothermia in rats the activity of isocitrate dehydrogenase (E.C.1.1.1.42) and malic dehydrogenase (E.C.1.1.1.37) was determined in the mitochondrial fraction of liver cells, myocardial cells and skeletal muscle fibres of the femoral muscle and no statistically significant differences were found between the obtained values and those in a control group. On the other hand, the activity of glucose-6-phosphate dehydrogenase (E.C.1.1.1.49) in the cytoplasmic fraction of these tissues was decreased in the hypothermic rats by 46% in the liver, by 50% in the myocardium and by 59% in the skeletal muscle of the thigh. A possible cause of this reduced activity of this enzyme in hypothermia could be changes in the structure of the enzymatic protein, deficiency of the hormone activating the enzyme, that is insulin, and/or inhibition of the pentose-phosphate cycle by fatty acids released in excess.
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PMID:Activity of certain enzymes in the mitochondrial and cytoplasmic fractions of liver cells, myocardium and skeletal muscle of the rat during short-lasting hypothermia. 718 57

Sixteen peptides were injected intracerebroventricularly to test their effects on rectal temperature of rabbits in a thermoneutral environment. In initial tests 5 micrograms alpha-MSH, ACTH(1--24), oxytocin, vasopressin and glucagon altered body temperature while ACTH(1--10), cholecystokinin, contraceptive tetrapeptide, gastrin, insulin, interferon, leupeptin, LHRH, panhibin (somatostatin), and proctolin did not. Bombesin also altered body temperature but in no consistent direction. In further tests on the effective peptides 1.25--5.0 micrograms alpha-MSH and ACTH(1--24) produced dose-related decreases in rectal temperature as great as 1.0 degrees C. The same doses of oxytocin and glucagon produced small, prolonged hyperthermias which did not exceed 0.4 degrees C. Vasopressin caused rapid development of small increases in rectal temperature; temperature returned to normal in 2--3 hr. The results suggest that five of the peptides tested may have roles in central mediation of normal body temperature, hypothermia, hyperthermia and fever.
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PMID:Central administration of peptides alters thermoregulation in the rabbit. 724 7

1. Plasma concentrations of glucose, lactate, amino acids, non-esterified fatty acids, glycerol, ketone bodies, insulin and cortisol were measured in 43 elderly patients with hypothermia. In 15 of these patients forearm arteriovenous differences were also measured. Core temperatures ranged from 25.9 to 35.5 degrees C. 2. The metabolic state was of mobilization of glycogen and triacylglycerol stores, with high plasma concentrations of lactate and lipid metabolites. The plasma concentration of glucose was raised in those with hypothermia of a short duration (less than 6 h). In other patients it was low in those with core temperatures around 30 degrees C, but below this temperature it was variable and often high. Concentrations of other metabolites or hormones were not related to core temperature. 3. Plasma concentrations of cortisol were high and positively correlated with those of lactate and glycerol, suggesting active involvement in stimulation of muscle glycogenolysis and of lipolysis. 4. Plasma concentrations of insulin ranged from very low to very high and appeared to depend on the concentrations of both glucose and alanine. 5. Arteriovenous differences were generally small. There was peripheral release of lactate and of amino acids but no overall peripheral uptake of glucose. In nine out of 15 patients there was a significant peripheral release of glucose.
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PMID:Metabolic aspects of hypothermia in the elderly. 747 42

We present a 66-year-old man with morning fasting hypoglycemia from an unknown cause associated with markedly suppressed levels of insulin. In this patient we examined the diurnal changes of plasma corticotropin-releasing hormone (CRH). ACTH, cortisol, glucose, insulin and body temperature, and the correlations among them. We also discussed an implication of plasma CRH in glucose metabolism by taking these findings together with results from previous studies on plasma CRH in diabetic or hypoglycemic animals and human beings. In this case, the stress induced by severe spontaneous hypoglycemia in the morning fasting state increased CRH in plasma compared to the euglycemia state and simultaneously activated the hypothalamic-pituitary-adrenal system as well as the sympathetic nervous system remarkably. The daily intravenous infusion of glucose brought the fasting hypoglycemia to normal and hypothermia to normothermia in the morning, and improved no or blunt responsiveness of insulin to glucose. On the 50th day of therapy, the i.v. infusion of glucose quickly produced moderate hyperglycemia and an increase in plasma insulin, and inhibited secretions of CRH, ACTH and cortisol. The source of plasma CRH remains obscure. However, the positive correlations of plasma CRH with both plasma ACTH and cortisol and several lines of evidence indicate that CRH in peripheral plasma is derived from both the hypothalamus and extrahypothalamic peripheral tissue and that during stressed conditions, in particular, the CRH increase in plasma is derived mainly from the paraventricular nucleus of the hypothalamus. The role of CRH not only in the systemic circulation but also in the endocrine pancreases for glucose metabolism remains to be clarified.
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PMID:[Peripheral plasma corticotropin-releasing hormone (CRH) in an aged patient with fasting hypoglycemia associated with an insufficient secretion of insulin: an implication of plasma CRH in glucose metabolism]. 755 77

Rats infused centrally with bombesin become hypothermic at normal ambient temperatures when acutely deprived of food, but not while allowed unrestrained access to food. Ad lib-fed rats, tested at normal ambient temperatures, become hypothermic after receiving intracerebroventricular (ICV) bombesin when they have ventromedial hypothalamic lesions or when administered insulin or 2-deoxy-D-glucose peripherally. All of these conditions have been linked to reductions of sympathetic nervous system activity to brown adipose tissue (BAT), a major thermogenic mechanism of many homeotherms. A between group design was used to examine the effects of ICV bombesin infusions on the response to peripheral injections of a) the sympathetic ganglionic blocker chlorisondamine (2.5 mg/kg, IP) in ad lib-fed rats, b) the nonspecific beta-agonist isoproterenol (30 mg/kg, IP) in food-deprived rats, and c) the combination of isoproterenol and chlorisondamine in ad lib-fed rats. Ad lib-fed rats receiving ICV bombesin (100 ng/5 microliters), in combination with peripheral chlorisondamine injection, became hypothermic 60 min postbombesin administration (-2.84 +/- 0.33 degrees C), while ad lib-fed rats receiving ICV bombesin infusion and peripheral injections of saline did not (-0.08 +/- 0.37 degrees C). Isoproterenol blocked hyperthermia in ad lib-fed rats injected with chlorisondamine and ICV bombesin. Food-derived rats receiving ICV bombesin infusion and peripheral saline injection exhibited hypothermia 60 min postbombesin administration (-2.51 +/- 0.29 degrees C). Peripheral injections of isoproterenol prevented bombesin-induced hypothermia in food-deprived rats. These data suggest that bombesin induces hypothermia at normal ambient temperatures when the sympathetic nervous system drive to BAT cannot be (or is not) activated.
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PMID:Bombesin-induced hypothermia in rats tested at normal ambient temperatures: contribution of the sympathetic nervous system. 760 92

The effect of centrally administered bombesin on core temperature was investigated in rats which had been chronically fitted with a cannula in the third cerebral ventricle and with an intraperitoneal temperature-monitoring radiotransmitter. Intracerebroventricularly administered bombesin (0.01, 0.1 or 1 microgram) resulted in hypothermia, the duration and depth of the effect being a function of the dose. The use of telemetry minimized experimental interventions in this study; the results demonstrate that the hypothermic response to bombesin is not dependent upon exposure to a low ambient temperature, food restriction or insulin treatment as suggested by previous studies involving measurement of core temperature by a rectal probe.
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PMID:Effect of bombesin on core temperature in rats: studies involving radiotelemetry. 801 60

As shown in our previous study, hypothermia provokes a variety of hormonal changes including inhibition of insulin secretion and increase in blood serum glucagon level. According to Therminarias et al. the administration of exogenous insulin to dogs subjected to hypothermia causes a calorigenic effect by enhancing oxygen consumption and rising the intensity of shivering thermogenesis. The study was aimed at establishing whether exogenous insulin administered to rats subjected to brief hypothermia and having the shivering thermogenesis blocked by thiobutabarbital anesthesia can influence rectal temperature, the levels of some hormones and energy metabolism. The results obtained suggest that 1) insulin administration causes an increase in the energy charge potential (ECP) both in the liver and in skeletal muscle of the rat, indicating the domination of anabolic processes both in normothermic and hypothermic conditions, 2) there is a negative correlation between the levels of insulin and free fatty acids and the activity of isocitric dehydrogenase in rat liver mitochondria, and 3) the administration of insulin at a dose provoking metabolic response both in normothermic and hypothermic conditions was ineffective in provoking temperature response, indicating the existence of a functional dissociation between the various effects of the same dose of exogenous insulin.
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PMID:[Effect of insulin on temperature and metabolic responses in rats during normothermia and hypothermia]. 805 Mar 87

Carbohydrate metabolism and insulin status have been studied in 89 patients with congenital heart valve defects operated on in conditions of profound perfusion-free hypothermic protection. It has been established that anesthesia, hypothermia, and surgical trauma are accompanied by hyperinsulinemia, which had nothing to do with the introduction of exogenic hormone. Insulin effect is attenuated and insulin resistance develops, which leads to a drop not only in glucose consumption but also in the consumption of glycolysis products. Single insulin injection during induction to anesthesia at a dose of 0.5 U/kg was insufficient for normalization of carbohydrate homeostasis. Glycolysis activation with a considerable increase in blood pyruvate level has been observed, which decreases lactate/pyruvate coefficient informative value at different stages of surgical treatment of heart valve defects.
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PMID:[Characteristics of carbohydrate metabolism regulation during correction of congenital heart defects and hypothermic protection without perfusion]. 808 Jan 21

The aim of the study was to estimate the effect of hypothermia on (125J)-iodoinsulin binding to liver plasma membranes. Rat liver membranes were prepared from control, normothermic rats (Tr = 35.6 +/- 0.3 degrees C) and hypothermic rats (Tr = 26.5 +/- 0.9 degrees C) and purified according to Havrankowa. In addition, serum insulin and glucagon levels by means of RIA and glucose concentration using the glucose oxidase method were measured. Scatchard analysis was used to determine the kinetic parameters of the hormone receptor interaction. The data showed no significant differences in the affinity of the binding sites but indicated a decrease in receptor concentrations in liver plasma membranes from hypothermic rats. In contrast to changes in serum insulin level which was decreased by about 50% in hypothermic rats blood glucose concentrations did not significantly differ between the hypothermic and normothermic ones. Our results show that in hypothermic rats the hormonal adaptation operates on the level of the number of liver receptors whereas the insulin receptor affinity remains unaffected.
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PMID:Effect of hypothermia on the insulin--receptor interaction in liver plasma membranes. 812 87

Advances in myocardial preservation have led to improved patient survival after open heart operations. However, few studies have detailed the nature of national or regional patterns of cardioplegia use. To determine the regional pattern, all open heart surgery programs in Missouri were surveyed. During 1 year, it was found that cardioplegia was administered to 8,382 patients by 61 cardiothoracic surgeons at ten academic affiliated hospitals and 16 nonteaching hospitals. All cardioplegic solutions were hospital produced. Of 13 crystalloid solutions, 11 differed from one another and eight were intracellular formulations. Of 28 multidose blood-based cardioplegic solutions, there were 23 different mixtures. Most crystalloid (69%) and blood-based (89%) solutions differed substantially from commonly reported formulations. The incidences of the various additives to crystalloid solutions were as follows: bicarbonate, 92%; glucose, 69%; lidocaine, 54%; mannitol, 46%; magnesium, 31%; calcium, 23%; methylprednisolone, 15%; heparin, 8%; and acetate, 8%. Of the common blood-based cardioplegic solution additives, the following incidences were observed: glucose, 79%; bicarbonate, 43%; trishydroxyaminomethane, 36%; acetate, 29%; magnesium, 29%; procaine (or lidocaine), 25%; citrate-phosphate-dextrose, 18%; mannitol/albumin, 14%; nitroglycerin, 11%; glutamate/aspartate, 11%; calcium, 7%; insulin, 3%; and methylprednisolone, 3%. No calcium channel blocker or high-energy phosphate additives were reported. We conclude that many different cardioplegic admixtures that have not been tested experimentally are used routinely in clinical practice, presumably with acceptable results. Because the salutary effects of induced cardiac arrest and hypothermia may mask suboptimal solutions, further study of customized cardioplegia should be considered, particularly with regard to high-risk patients.
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PMID:Lack of cardioplegia uniformity in clinical myocardial preservation. 814 36


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