Changes of body fluid and hematology in toad and their rehabilitation following intermittent exposure to simulated high altitude

Three groups of adult male toads were exposed intermittently in a decompression chamber for a daily period of 4 and 8 hours at a time for 6 consecutive days to an altitude of 12,000; 18,000 and 24,000 feet (3658; 5486; 7315 m) respectively. Most of the exposed animals were sacrificed immediately after the last exposure, but only a few animals experiencing 8 hours of exposure were sacrificed after a further 16 hours of exposure at normal atmospheric pressure. Eight hours of daily exposure for 6 days causes a decrease of body fluids and an increase of hematological parameters in all the altitude exposed animals compared with to the changes noted in the animals having 4 hours of daily exposure for 6 days at the same altitude levels. The animals that were exposed to pressures equivalent to altitudes of 12,000 and 18,000 feet daily for 8 hours were found to return nearly to their normal body fluids and hematological balance after 16 hours of exposure to normal atmospheric pressure, whereas the animals exposed for a similar period at an equivalent 24,000 feet failed to get back their normal balance of body fluids and hematology after 16 hours of exposure at normal atmospheric pressure. The present experiment shows that the body weight loss and changes of body fluid and hematological parameters in the toad after exposure to simulated high altitude are due not only to dehydration, but suggest that hypoxia may also have a role.     

Tissue weights and adaptation response of the toad after 96 hours of exposure to simulated high altitude — A body fluid and hematological study

Adult male toads were exposed to simulated high altitude of 24,000 feet for 96 hrs of continuous exposure in a decompression chamber. The animals were sacrificed immediately after the exposure period. Significant increase of the weight of the ventricle and spleen is observed in altitude exposed animals. Red blood cell, hemoglobin concentration, hematocrit ratio and red cell mass are significantly increased in high altitude exposed animals in comparison to control. MCV (mean corpuscular volume) and MCH (mean corpuscular hemoglobin) are decreased in altitude exposed group. Plasma volume, blood volume, extracellular fluid volume, intracellular fluid volume and total body water are decreased significantly after altitude exposure for 96 hrs. These physiological changes are thought to be due to dehydration of this animal at simulated high altitude and it is highly affected after 96 hrs of exposure as evidenced by the significant reduction of total body water and intracellular fluid volume.     

Changes in the activity levels of glutamine synthetase, glutaminase and glycogen synthetase in rats subjected to hypoxic stress

 Exposure to high altitude causes loss of body mass and alterations in metabolic processes, especially carbohydrate and protein metabolism. The present study was conducted to elucidate the role of glutamine synthetase, glutaminase and glycogen synthetase under conditions of chronic intermittent hypoxia. Four groups, each consisting of 12 male albino rats (Wistar strain), were exposed to a simulated altitude of 7620 m in a hypobaric chamber for 6 h per day for 1, 7, 14 and 21 days, respectively. Blood haemoglobin, blood glucose, protein levels in the liver, muscle and plasma, glycogen content, and glutaminase, glutamine synthetase and glycogen synthetase activities in liver and muscle were determined in all groups of exposed and in a group of unexposed animals. Food intake and changes in body mass were also monitored. There was a significant reduction in body mass (28–30%) in hypoxia-exposed groups as compared to controls, with a corresponding decrease in food intake. There was rise in blood haemoglobin and plasma protein in response to acclimatisation. Over a three-fold increase in liver glycogen content was observed following 1 day of hypoxic exposure (4.76±0.78 mg·g⁻¹ wet tissue in normal unexposed rats; 15.82±2.30 mg·g⁻¹ wet tissue in rats exposed to hypoxia for 1 day). This returned to normal in later stages of exposure. However, there was no change in glycogen synthetase activity except for a decrease in the 21-days hypoxia-exposed group. There was a slight increase in muscle glycogen content in the 1-day exposed group which declined significantly by 56.5, 50.6 and 42% following 7, 14, and 21 days of exposure, respectively. Muscle glycogen synthetase activity was also decreased following 21 days of exposure. There was an increase in glutaminase activity in the liver and muscle in the 7-, 14- and 21-day exposed groups. Glutamine synthetase activity was higher in the liver in 7- and 14-day exposed groups; this returned to normal following 21 days of exposure. Glutamine synthetase activity in muscle was significantly higher in the 14-day exposed group (4.32 μmol γ-glutamyl hydroxamate formed·g protein⁻¹·min⁻¹) in comparison to normal (1.53 μmol γ-glutamyl hydroxamate formed·g protein⁻¹·min⁻¹); this parameter had decreased by 40% following 21 days of exposure. These results suggest that since no dramatic changes in the levels of protein were observed in the muscle and liver, there is an alteration in glutaminase and glutamine synthetase activity in order to maintain nitrogen metabolism in the initial phase of hypoxic exposure. Received: 30 March 1998 / Revised: 18 November 1998 / Accepted: 25 November 1998     

The importance of glucose for the freezing tolerance/intolerance of the anuran amphibians Rana catesbeiana and Bufo paracnemis

Several species of terrestrially hibernating frogs, turtles and insects have developed mechanisms, such as increased plasma glucose, anti-freeze proteins and antioxidant enzymes that resist to freezing, for survival at subzero temperatures. In the present study, we assessed the importance of glucose to cryoresistance of two anuran amphibians: the frog Rana catesbeiana and the toad Bufo paracnemis. Both animals were exposed to -2 degrees C for measurements of plasma glucose levels, liver and muscle glycogen content, haematocrit and red blood cell volume. Frogs survived cold exposure but toads did not. Blood glucose concentration increased from 40.35 +/- 7.25 to 131.87 +/- 20.72 mg/dl (P < 0.01) when the frogs were transferred from 20 to -2 degrees C. Glucose accumulation in response to cold exposition in the frogs was accompanied by a decrease (P < 0.05) in liver glycogen content from 3.94 +/- 0.42 to 1.33 +/- 0.36 mg/100 mg tissue, indicating that liver carbohydrate reserves were probably the primary carbon source of glucose synthesis whereas muscle carbohydrate seems unimportant. In the toads, the cold-induced hyperglycaemia was less (P < 0.05) pronounced (from 27.25 +/- 1.14 to 73.72 +/- 13.50 mg/dl) and no significant change could be measured in liver or muscle glycogen. Cold exposition had no effect on the haematocrit of the frogs but significantly reduced (P < 0.01) the haematocrit of toads from 20.0 +/- 2.1% to 5.8 +/- 1.7% due to a decreased red blood cell volume (from 1532 +/- 63 to 728 +/- 87 mm3). When toads were injected with glucose, blood glucose increased to levels similar to those of frogs and haematocrit did not change, but this failed to make them cryoresistent. In conclusion, the lack of cold-induced glucose catabolism may not be the only mechanism responsible for the freeze intolerance of Bufo paracnemis, a freeze-intolerant species.     

The whey proteins of the milk of red deer (Cervus elaphus L.). A homologue of bovine beta-lactoglobulin.

Increasing plasma free fatty acids decreased the degree of glycogen depletion, and increased the citrate concentration, in slow-red (soleus) and fast-red (deep portion of vastus lateralis) muscle during exercise (approx. 50% depletion of glycogen, as against 75% in control animals). There was no effect in fast-white muscle (superficial portion of vastus lateralis). Glycogen concentration in the liver decreased by 83% in controls, but only by 23% in animals with increased free fatty acids during exercise. The decreased glycogen depletion may be partly explained by the findings that (a) plasma-insulin concentration was two- to three-fold higher in animals with increased plasma free fatty acids and (b) the exercise-induced increase in plasma glucagon was lessened by increased free fatty acids. Blood glucose was higher in the animals with increased free fatty acids after the exercise. The rats with increased plasma free fatty acids utilized approx. 50% as much carbohydrate as did the controls during the exercise.     

In vivo tissue specific modulation of rat insulin receptor gene expression in an experimental model of mineralocorticoid excess

Insulin receptor (IR) gene expression at the mRNA level was investigated in hindlimb skeletal muscle, epididymal adipose tissue and in the liver of rats exposed to prolonged in vivo administration of deoxycorticosterone acetate (DOCA). Following treatment, plasma insulin levels were reduced while glucose levels increased compared to values in control rats. DOCA-treated animals showed an increase in blood pressure and a reduction in body weight. This treatment also induced hypokalemia and decreased plasma protein levels. Sodium levels were unaffected. Moreover, no differences in DNA and protein content or in the indicator of cell size (protein/DNA) were observed in the skeletal muscle or adipose tissue of animals. In contrast, there was a clear increase in the protein and DNA contents of the liver with no change in the indicator of cell size. Northern blot assays revealed 2 major IR mRNA species of approximately 9.5 and 7.5 Kb in the 3 tissues from control animals. DOCA treatment induced no change in the levels of either RNA species in skeletal muscle. However, a decrease of approximately 22% was detected in the levels of both species in adipose tissue whereas the liver showed an increase of 64%. These results provide the first evidence for an in vivo tissue-specific modulation of IR mRNA levels under experimental conditions of mineralocorticoid excess.     

The influence of postnatal nutritional deprivation on the phospholipid content of developing rat lung.

It has been previously reported that fasting may result in decreased lung surfactant production. In order to investigate this relationship and the role of nutrition in lung phospholipid synthesis, 21-day-old rats were exposed for 60 h to one of five dietary regimens: standard rat chow (controls), fasting, pure glucose, pure fat, or pure protein. After the period of fasting there was a 33% decrease in lung protein content, but there was no change in DNA content. Exposure to any of the experimental diets resulted in a decrease in tissue total phospholipid and phosphatidylcholine content per lung, but not per unit lung protein. Similarly lung lavage phospholipid and phosphatidylcholine content was decreased by 25% after fasting when expressed per lung or per unit DNA, but not per unit protein. Pulmonary cholinephosphotransferase (EC 2.7.8.2) activity was decreased in the fasted animals and those fed the protein diet, but not in the glucose or fat-fed animals. The activities of acetyl-CoA carboxylase (EC 6.4.1.2) and microsomal fatty acid elongation were decreased in all the experimental groups except for the glucose-fed group. It is concluded that fasting results in a decrease in lung cell size but not in lung cell number. Total phospholipid and phosphatidylcholine content in lung tissue and lung lavage is decreased per cell but not per unit cell mass.     

Stimulation of anaerobic metabolism in rats at high altitude hypoxia--adrenergic effects dependent on dietary states

1. Plasma lactate and pyruvate were increased more markedly in fed rats than in fasted rats exposed to an 8000 m altitude. 2. The increase in plasma lactate and pyruvate was enhanced and inhibited by the alpha 1-adrenergic antagonist prazosin and the beta-blocker propranolol, respectively, in fasted rats exposed to an 8000 m altitude. Blood glucose was not changed by adrenergic blockades under the same conditions. 3. Prazosin and propranolol showed no effect on glycolytic metabolites in plasma in fed rats submitted to an 8000 m altitude. Blood glucose of fed rats was increased by alpha 1-blockade during severe hypoxia. 4. In fasted rats whose energy metabolism depends on oxidation mainly, alpha 1- and beta-adrenergic receptors can participate in the stimulation of respiration and the glycogen degradation, respectively, during an exposure to severe hypoxia. In fed rats energy metabolism depends on glycolysis, which utilizes blood glucose as the substrate preferentially during hypoxia.     

Purification and characterization of two lectins from Aloe arborescens Mill.

Two lectins have been isolated from leaves of Aloe arborescens Mill by salt precipitation, pH-dependent fractionation and gel filtration. One lectin (P-2) has a molecular weight of approximately 18,000, consists of two subunits (alphabeta) and contains more than 18% by weight of neutral carbohydrate. The smaller subunit (alpha) has a molecular weight of approximately 7,500 and the larger subunit (beta) a molecular weight of approximately 10,500. The other lectin (S-1) has a molecular weight of approximately 24,000, consists of two subunits (gamma2) with a molecular weight of approximately 12,000 and contains more than 50% by weight of neutral carbohydrate. An interesting feature of the amino acid compositions of these lectins is the high proportion of acidic amino acids, such as aspartic acid and glutamic acid, and the low proportion of methionine and histidine. S-1 has a strong hemagglutinating activity. On the other hand, P-2 has not only hemagglutinating activity but also mitogenic activity on lymphocytes, precipitate-forming reactivity with serum proteins, one of which is alpha2-macroglobulin, and complement C3 activating activity via the alternate pathway.     

Changes in metabolite concentration in the plasma, liver and muscle of feed restricted Japanese quail exposed to cold.

Quail fed ad libitum and 50% ad libitum were cold exposed for several weeks, during time control quail remained at 21 degrees C. The concentration of plasma glucose, FFA, and uric acid, tissue glycogen and carcass fat content was measured at the end of the cold exposure period. Quail fed ad libitum showed no significant change in the levels of plasma and tissue metabolites, or the carcass fat content, following cold exposure. The feed consumption by the cold exposed quail increased, and the mean body weight showed little variation from that of the controls. Feed restricted quail which were cold exposed lost significantly more weight, and had a lower ranked fat content than their controls. Whereas feed restriction caused a lowering of the liver glycogen concentration in both treatment groups, muscle glycogen levels were higher than in quail fed ad libitum. However, cold exposure was not accompanied by a change in muscle and liver glycogen levels in feed restricted quail. Feed restricted quail at 21 degrees C were hypoglycaemic and hyperlipaemic compared to quail fed ad libitum, but cold exposed feed restricted quail had a much higher plasma glucose concentration than the controls. The ranked carcass fat content was inversely related to plasma FFA level in both control and cold exposed feed restricted quail. It is suggested that both a glycolytic and lipid mobilizing response to cold is obtained in quail whose body reserves are not spared from catabolism by adequate dietary nutrient absorption, and the possibility of gluconeogenesis from precursors produced by proteolysis is indicated.     

Dopamine-containing substantia nigra units are unresponsive to changes in plasma glucose levels induced by dietary factors, glucose infusions or insulin administration in freely moving cats

Dopamine-containing neurons in the pars compacta of the substantia nigra showed no significant change in activity during 48 hours of food deprivation in cats that were maintained on either a high carbohydrate diet or a low carbohydrate-high protein diet. Plasma glucose levels declined significantly during this time period in the high carbohydrate diet group, and increased slightly in the low carbohydrate-high protein diet group. In addition, there was no significant change in the activity of dopaminergic neurons in food deprived cats during feeding behavior, during which glucose levels were restored to normal. Intravenous infusion of glucose in freely moving cats, which elevated plasma glucose levels from 82 to 719 mg/100 ml and midbrain glucose from 4.3 to 12.2 mumoles/g, was also without effect on the activity of dopaminergic neurons. Insulin administration to cats maintained on a diet of standard cat chow and fasted for 18 hours decreased plasma and brain glucose to 32.8 mg/100 ml and 2.1 mumoles/g, respectively, but, again, there was no significant change in nigral unit activity. These data demonstrate that central dopaminergic neurons are unresponsive to fluctuations in brain and plasma glucose, and argue against a role for central dopamine systems in the regulation of feeding behavior and energy metabolism.     

Human Immune Circadian System in Prolonged Mild Hypoxia during Simulated Flights

An impairment of immunity is reported after long‐haul flights, and the mild hypobaric hypoxia caused by pressurization in the passenger airline cabin may contribute to it. In this controlled crossover study, the effects of two levels of hypoxia, equivalent to 8000 and 12,000 feet above sea level, on the rhythm of CD3, CD4, and CD8 lymphocytes and plasma concentrations of the immunoglobulins A, G, and M were assessed. Fourteen healthy male volunteers, aged 23 to 39 years, spent 8.5 h in a hypobaric chamber (08:00 to 16:30 h), simulating an altitude condition at 8,000 feet. This was followed by an additional 8.5 h study four weeks later simulating altitude conditions at 12,000 feet. The variables were assayed every 2 h over two 24 h cycles (control and hypoxic‐exposure cycles). No significant effect of hypoxia on the studied circadian immune profiles were found. Therefore, the authors conclude that mild hypobaric hypoxia does not seem to be responsible for any quantitative changes during long‐haul flights in the immune assays commonly used in routine clinical medicine practice.     

急性低氧暴露小鼠外周血代谢组变化分析

目的：探讨急性低氧对小鼠外周血代谢组的影响。方法：将14只小鼠随机分为正常组和低氧组。用基础饲料喂养2周后,将低氧组减压至6000m模拟高度停留8h,实验结束后,采集静脉血制备血浆待测。在核磁共振波谱仪进行^1H NMR检测,采用模式识别分析方法处理数据。结果：与正常组相比,低氧组乳酸含量明显增加,肉碱水平明显降低;脂类、丙氨酸、丙酮酸、谷氨酰胺、胆碱、牛磺酸和葡萄糖含量升高,缬氨酸、肛羟丁酸、谷氨酸、甘油、甘氨酸和丝氨酸含量下降。结论：急性低氧暴露使小鼠血浆碳水化合物、脂肪代谢和氨基酸代谢谱发生变化,表明低氧后能量代谢以及相关物质含量发生改变。     

Adipocytes utilize sucrose as an energy source—Effect of different carbohydrates on adipocyte differentiation

Adipose tissue is a complex and heterogenic tissue exhibiting high variability and appears to have multiple functions, especially in metabolic regulation. Change in carbohydrate source is reported to have a profound effect in the regular functioning of adipocytes. Here, we analyzed the role of two monosaccharides namely, glucose (5.2 and 25 nM), galactose (25 mM), and two disaccharides namely, lactose and sucrose (both at 25 mM) in the adipocyte differentiation process and its utilization by adipocytes as an energy source. The change in cell morphology, adipocyte-specific gene expression, and protein levels were analyzed at three different time points: 2, 6, and 48 hr. Oil Red O staining at Day 8 of differentiation showed that no other carbohydrates were able to increase lipid content as better as 25 mM glucose. Gene expression pattern was altered by the change in glucose concentration and sucrose was able to mimic the effect of glucose even though, the lipid synthesis was solely promoted by high glucose levels. Galactose and lactose did not show any effect in promoting adipocyte differentiation. The expression of PPAR γ was high in the presence of sucrose and galactose, possibly of adipogenic cocktail in enhancing the expression rather than the effect of carbohydrate. Acarbose, a potent glucosidase inhibitor was able to inhibit the lipid content in adipocytes grown with sucrose as a carbohydrate source and shows the possibility of its direct utilization. Lactate production by cells upon differentiation also proved the possible uptake of glucose after sucrose cleavage.     

Alterations in plasma-volume-corrected blood components of marathon runners and concomitant relationship to performance

The study was undertaken to determine the effects of running a marathon on concentration of various blood components resulting from phenomena other than fluid loss, and these were related to performance times. Twenty male marathon runners ranging from 20 to 50 years of age participated in the study. Blood samples were collected before and after the subjects ran in a marathon. Blood samples were analyzed for sodium, potassium, glucose, lactate dehydrogenase, creatinine, creatine phosphokinase, triglycerides, cholesterol, hematocrit, hemoglobin, protein, white blood cell number, uric acid, carbon dioxide, and iron. All of the blood parameters increased significantly in concentration with the exceptions of glucose and carbon dioxide which decreased. After accounting for plasma-volume loss (COR), there remained significant increases in blood serum lactate dehydrogenase, creatinine, creatine phosphokinase, uric acid, iron, and whole-blood white blood cell number. Significant decreases in COR serum sodium, protein, glucose, and carbon dioxide were found. Lactate dehydrogenase and creatine phosphokinase concentration changes support the concept of acute damage to muscle tissue resulting from marathon running. No strong relationship between performance time and other measured variables was found. COR measures were more representative of marathon induced blood changes from physiological dynamics other than plasma volume change than presently reported findings.     

Human immune circadian system in prolonged mild hypoxia during simulated flights

An impairment of immunity is reported after long-haul flights, and the mild hypobaric hypoxia caused by pressurization in the passenger airline cabin may contribute to it. In this controlled crossover study, the effects of two levels of hypoxia, equivalent to 8000 and 12,000 feet above sea level, on the rhythm of CD3, CD4, and CD8 lymphocytes and plasma concentrations of the immunoglobulins A, G, and M were assessed. Fourteen healthy male volunteers, aged 23 to 39 years, spent 8.5 h in a hypobaric chamber (08:00 to 16:30 h), simulating an altitude condition at 8,000 feet. This was followed by an additional 8.5 h study four weeks later simulating altitude conditions at 12,000 feet. The variables were assayed every 2 h over two 24 h cycles (control and hypoxic-exposure cycles). No significant effect of hypoxia on the studied circadian immune profiles were found. Therefore, the authors conclude that mild hypobaric hypoxia does not seem to be responsible for any quantitative changes during long-haul flights in the immune assays commonly used in routine clinical medicine practice.     

不同强度运动结合白藜芦醇对老年肥胖大鼠RBP4的影响

目的：探讨不同强度运动结合白藜芦醇对老年肥胖大鼠内脏脂肪组织视黄醇结合蛋白4（RBP4） mRNA蛋白表达及血浆RBP4浓度的影响。方法：选择鼠龄3周的雄性SD大鼠80只,随机分为对照组和实验组：对照组（C）饲喂6.0%脂肪的普通饲料（n=12）;实验组分3个阶段饲喂36%~40%高脂饲料（n=68）。建立老年肥胖大鼠模型,选取24只建模成功的肥胖大鼠随机分为4组（n=6）：肥胖对照组（CO）、白藜芦醇组（RO）、低强度运动+白藜芦醇组（LRO）、中强度运动+白藜芦醇组（MRO）。LRO组和MRO组的运动强度分别为（12 m/min×15 min）和（15 m/min×15 min）,每天运动60 min;补充白藜芦醇各组52.5 mg/kg·d灌胃1次,对照组采用等量的纯净水灌胃,持续干预8周。8周后采血和肾周、睾周、血管及内脏脂肪组织,检测血糖和血浆RBP4浓度、计算胰岛素敏感性（ISI）,检测RBP4 mRNA和蛋白表达。结果：与正常组比较,模型组大鼠RBP4 mRNA和蛋白表达、血浆浓度及血糖指标明显升高（P<0.05,P<0.01）,ISI明显降低（P<0.05）;与模型组比较,RO、LRO组和MRO组大鼠RBP4 mRNA和蛋白表达、血浆浓度及血糖指标明显降低（P<0.05,P<0.01）,ISI明显升高（P<0.05）;RO、LRO组和MRO组之间比较,MRO组大鼠RBP4 mRNA和蛋白表达、血浆浓度及血糖指标明显降低,ISI明显升高,但无显著差异。结论：不同强度运动结合白藜芦醇能降低老年肥胖大鼠内脏脂肪组织RBP4 mRNA和蛋白表达及血浆RBP4浓度,受运动强度影响较小。     

Effects of pyrazidol on resistance of animals to hypobaric hypoxia]

The influence of monoamine oxidase type A inhibitor pyrazidol on rats sensitivity to hypobaric hypoxia was investigated. Preliminary pyrazidol administration shows evident protective effect under hypoxia. It increases animals survival at the altitude of 12,000 m above the sea level, prevents lungs affection and erythrocyte membrane destabilization at the altitude of 9,000 m during 3 hours. Plasma total peroxidase activity, extraerythrocyte hemoglobin concentration and free iron content were used as the indexes of erythrocyte membrane stability reflecting the organism state under stress effects.     

Differential regulation of glucose transporter gene expression in adipose tissue or septic rats.

To understand the molecular mechanisms responsible for the sepsis-induced enhanced glucose uptake, we have examined the levels of GLUT4 and GLUT1 mRNA and protein in the adipose tissue of septic animals. Rats were challenged with a nonlethal septic insult where euglycemia was maintained and hexose uptake in adipose tissue was markedly elevated. Northern blot analysis of total RNA isolated from epididymal fat pads indicated differential regulation of the mRNA content for the two transporters: GLUT1 mRNA was increased 2.6 to 4.6-fold, while GLUT4 mRNA was decreased by 2.5 to 2.9-fold. Despite the difference in mRNA levels, both GLUT1 and GLUT4 protein were down regulated in plasma membranes (40% and 25%, respectively) and microsomal membranes (42% and 25%, respectively) of the septic animals. The increased glucose uptake cannot be explained by the membrane content of GLUT1 and GLUT4 protein. Thus, during hypermetabolic sepsis, increased glucose utilization by adipose tissue is dependent on alternative processes.