Fever in young lambs: temperature, metabolic and cardiorespiratory responses to a small dose of bacterial pyrogen

Experiments were done on ten lambs ranging in age from 15 to 25 days to define the temperature, metabolic and cardiorespiratory responses to intravenous administration of a small dose of bacterial pyrogen (SAE). Administration of SAE but not normal saline produced a short-lived fever of about 0.7 degrees C. The increase in body-core temperature was preceded by a surge in total body oxygen consumption and the onset of shivering which was influenced by behavioral state (ie, shivering was inhibited during active sleep). The increase in total body oxygen consumption was initially met by an increase in total body oxygen extraction and then by an increase in systemic oxygen delivery. Systemic arterial blood pressure did not change significantly during the febrile response; however, pulmonic arterial blood pressure increased significantly. Thus, our experiments provide new data on oxygen supply and demand during the development of fever and that shivering thermogenesis is inhibited in active sleep following the administration of bacterial pyrogen in young lambs. The influence of active sleep on the overall febrile response, and whether or not there is a shift from shivering thermogenesis to non-shivering thermogenesis remains to be determined.     

Fever in young lambs: hypoxemia alters the febrile response to a small dose of bacterial pyrogen.

Experiments were done on eight young lambs to investigate the effects of hypoxemia on the body temperature, metabolic and cardiovascular responses to intravenous administration of a small dose of bacterial pyrogen (0.3 micrograms lipopolysaccharide extracted from Salmonella Abortus Equi; SAE). Each lamb was anaesthetized with halothane and prepared for sleep staging and measurements of cardiac output, arterial and mixed-venous haemoglobin oxygen saturations, body-core and ear-skin temperatures. Three experiments were done on each lamb, the first being done no sooner than three days after surgery. The first experiment consisted of establishing the thermal neutral environment during normoxemia (ie, environmental temperature at which total body oxygen consumption was minimal while body temperature was maintained) for each lamb. The second and third experiments were done at the lamb's thermoneutral environment as determined on day 1. One experiment was done during normoxemia (ie, control condition, SaO2 approximately 90%) and one experiment was done during hypoxemia (ie, experimental condition, SaO2 approximately 50%). Measurements were made during a control period and during one-minute experimental periods at 10 minute intervals for 120 minutes following administration of 0.3 micrograms of bacterial pyrogen in sterile saline. Administration of SAE produced a short-lived fever of about 0.8 degrees C in the normoxemic lambs, whereas no change in body-core temperature was observed in the hypoxemic lambs. During normoxemia, the increase in body-core temperature was preceded by peripheral vasoconstriction, the onset of shivering, and a surge in total body oxygen consumption. The increase in total body oxygen consumption was met primarily by an increase in total body oxygen extraction during the development of fever. Cardiac index, heart rate, and systemic oxygen transport increased during the peak body-core temperature response. Systemic arterial blood pressure did not change significantly during the febrile response; however, pulmonic arterial blood pressure increased. During hypoxemia, peripheral vasoconstriction and shivering occurred following administration of SAE, but there was no change in total body oxygen consumption or body-core temperature. Thus, our data provide evidence that hypoxemia alters the febrile response of young lambs to bacterial pyrogen. The precise mechanism remains to be determined.     

Effects of Argon on Oxygen Consumption in Humans during Physical Exercise under Hypoxic Conditions

An increase in oxygen consumption was observed in healthy male subjects breathing argon-containing gas mixtures during physical exercise. According to a detailed analysis of the methodology and calculations, this effect exceeded the possible errors in the measurements. It was proposed that argon has a catalytic effect on the kinetics of oxygen consumption as an attempt to explain two of its known effects, i.e., an increase in oxygen consumption in human subjects breathing moderately hypoxic gas mixtures and an increase in the survival rates observed previously for rats in acute hypoxia.     

The central effect of 5-hydroxytryptamine, gamma-amino-butyric acid and carbachol on thermoregulation in the neonatal guinea pig.

5-Hydroxytryptamine (10 microgram), gamma-amino-butyric acid (20 microgram) and carbachol (1 microgram) were injected through the soft skull into the lateral cerebral ventricle of guinea pigs aged 2 to 12 days, at the slightly subneutral ambient temperature of 30 degrees C. 5-Hydroxytryptamine (5-HT) produced no immediate change in oxygen consumption, whereas colonic temperature fell rapidly. One hour after injecting 5-HT, when colonic temperature had decreased by about 0.5 degrees C, oxygen consumption increased and after a lag of 30--40 min was followed by an increase in colonic temperature. Gamma-amino-butyric acid (GABA) increased oxygen consumption and colonic temperature after a latency of 30--60 min. Carbachol was followed by an immediate decrease in colonic temperature and oxygen consumption. Colonic temperature was below the pre-injection level throughout the five-hour period of observation.     

Circulatory limits to oxygen supply during an acute temperature increase in the Chinook salmon (Oncorhynchus tshawytscha)

This study was undertaken to provide a comprehensive set of data relevant to disclosing the physiological effects and possible oxygen transport limitations in the Chinook salmon (Oncorhynchus tshawytscha) during an acute temperature change. Fish were instrumented with a blood flow probe around the ventral aorta and catheters in the dorsal aorta and sinus venosus. Water temperature was progressively increased from 13 degrees C in steps of 4 degrees C up to 25 degrees C. Cardiac output increased from 29 to 56 ml.min(-1).kg(-1) between 13 and 25 degrees C through an increase in heart rate (58 to 105 beats/min). Systemic vascular resistance was reduced, causing a stable dorsal aortic blood pressure, yet central venous blood pressure increased significantly at 25 degrees C. Oxygen consumption rate increased from 3.4 to 8.7 mg.min(-1).kg(-1) during the temperature increase, although there were signs of anaerobic respiration at 25 degrees C in the form of increased blood lactate and decreased pH. Arterial oxygen partial pressure was maintained during the heat stress, although venous oxygen partial pressure (Pv(O(2))) and venous oxygen content were significantly reduced. Cardiac arrhythmias were prominent in three of the largest fish (>4 kg) at 25 degrees C. Given the switch to anaerobic metabolism and the observation of cardiac arrhythmias at 25 degrees C, we propose that the cascade of venous oxygen depletion results in a threshold value for Pv(O(2)) of around 1 kPa. At this point, the oxygen supply to systemic and cardiac tissues is compromised, such that the oxygen-deprived and acidotic myocardium becomes arrhythmic, and blood perfusion through the gills and to the tissues becomes compromised.     

Interactions of temperature and sublethal environmental copper exposure on the energy metabolism of bluegill, Lepomis macrochirus Rafinesque

Copper (0.21 mgl⁻¹) caused a decrease in whole body oxygen consumption in bluegills exposed for 32 days, but no changes occurred during days 3, 4 or 9 of copper exposure. In vitro oxygen consumption of gill and brain, were not significantly altered, whereas liver Q O₂, was slightly elevated which suggests that copper is acting to decrease oxygen consumption of the whole animal at a higher level of integration than these individual tissues. In fish subjected to an increase in temperature as well as sublethal copper exposure, whole body oxygen consumption was higher than controls 5 days after the temperature was increased, indicating a delay in temperature acclimation in the copper exposed fish. This difference was reflected in higher in vitro oxygen consumption in the liver and gill of these fish suggesting the metal was delaying the process of temperature acclimation by at least in part acting directly on the tissues.     

CH-19 Sweet,a Non-Pungent Cultivar of Red Pepper,Increased Body Temperature and Oxygen Consumption in Humans

We investigated the effect of CH-19 Sweet, a nonpungent cultivar of red pepper, on body temperature and oxygen consumption in humans. CH-19 Sweet was given to 11 healthy volunteers, and core body temperature, body surface temperature and oxygen consumption were measured. The control group ingested California-Wandar, which contained neither capsaicin nor capsiate. The core body temperature in the CH-19 Sweet group was significantly higher than that in the control group (P<0.01). The forehead temperature measured by infrared thermography in the CH-19 Sweet group was significantly higher than that in the control group. The body surface temperature was increased for about 20 min after consumption of CH-19 Sweet intake, and the neck temperature was significantly higher (P<0.001) than when the subjects consumed California-Wandar. We also measured respiratory gas by indirect calorimetry while subjects wore a face mask. A significant difference was detected in oxygen consumption between the two groups, and the value was significantly higher in the CH-19 Sweet group (P<0.03). These results suggest that CH-19 Sweet increased thermogenesis and energy consumption.     

Oxygen consumption by developing and diapausing eggs of Eupholidoptera smyrnensis (Orthoptera: Tettigoniidae)

Oxygen consumption by eggs of the Mediterranean bush-cricket Eupholidoptera smyrnesis was manometrically measured at 18, 24, 30 and 33°C. The aim was to study changes in oxygen consumption during embryonic development, and to compare a facultative initial and a facultative penultimate diapause with subitaneous developing eggs and an obligatory final diapause. In developing eggs, oxygen consumption increased as the embryo grew, but remained constant during katatrepsis. A comparison of the different diapauses revealed that in the initial diapause, oxygen consumption was lower than that of the corresponding embryonic stage in subitaneous eggs; the temperature dependence of oxygen consumption was also low. In contrast, in penultimate and in final diapause, oxygen consumption remained at the same high level as in developing embryos of the same size, and the temperature dependence of oxygen consumption was high. The results suggest that it is energetically profitable to the embryo to spend the hot season in a facultative initial and/or penultimate diapause.     

CH-19 sweet, a non-pungent cultivar of red pepper, increased body temperature and oxygen consumption in humans.

We investigated the effect of CH-19 Sweet, a non-pungent cultivar of red pepper, on body temperature and oxygen consumption in humans. CH-19 Sweet was given to 11 healthy volunteers, and core body temperature, body surface temperature and oxygen consumption were measured. The control group ingested California-Wandar, which contained neither capsaicin nor capsiate. The core body temperature in the CH-19 Sweet group was significantly higher than that in the control group (P<0.01). The forehead temperature measured by infrared thermography in the CH-19 Sweet group was significantly higher than that in the control group. The body surface temperature was increased for about 20 min after consumption of CH-19 Sweet intake, and the neck temperature was significantly higher (P<0.001) than when the subjects consumed California-Wandar. We also measured respiratory gas by indirect calorimetry while subjects wore a face mask. A significant difference was detected in oxygen consumption between the two groups, and the value was significantly higher in the CH-19 Sweet group (P<0.03). These results suggest that CH-19 Sweet increased thermogenesis and energy consumption.     

The effects of temperature on the energetics of rectal fluid transport

Injections of fluid into the recta of isolated abdomens of the Pyrenean grasshopper Oedipoda germanica pyrenaica resulted in an immediate and sustained stimulation of oxygen consumption. The net increase in oxygen consumption was linearly related to the amount of fluid absorbed by the rectum. Rates of fluid absorption were temperature independent but the aerobic cost of fluid uptake increased 3.7-fold between 15 and 25°C. Overall rectal fluid absorption was estimated to account for 4% of the daily resting rate of oxygen consumption.     

The effect of extrinsic and intrinsic factors on oxygen consumption by the southern rock lobster, Jasus edwardsii

The oxygen consumption rate of the southern rock lobster, Jasus edwardsii, was evaluated in response to body weight, temperature, activity, handling, diurnal rhythm, feeding and oxygen saturation level. There was a positive relationship between standard oxygen consumption (M(O(2))) and both body weight and water temperature. The relationship between total oxygen consumption and wet whole body weight was described by the equation: LogM(O(2))=0.595log W-0.396 (r(2)=0.83). The relationship between weight-specific oxygen consumption and temperature was described by the equation: LogM(O(2))=0.047T-2.25 (r(2)=0.94). Activity had a significant influence on the oxygen consumption rate, causing a three-fold increase above the standard rate at the temperature of acclimation (13 degrees C). However, at temperatures approaching the upper and lower extremes, lobsters had a decreased ability to increase their oxygen consumption rates during activity. Lobsters took 4.5-5 h to return to standard oxygen consumption rates after a period of emersion and handling. A strong diurnal rhythm to oxygen consumption was recorded. J. edwardsii displayed a classic postprandial increase in oxygen consumption. A peak (1.72 times standard M(O(2))) occurred 10-13 h after feeding with an increase above standard M(O(2)) being maintained for 42 h. In its rested state J. edwardsii was an oxygen regulator down to a critical oxygen tension of 58 Torr, whilst activity resulted in the critical oxygen tension increasing to 93 Torr.     

Effect of Temperature on the Rate of Oxygen Consumption during the Second Half of Embryonic and Early Postembryonic Development of European Pond Turtle <Emphasis Type="Italic">Emys orbicularis</Emphasis> (Reptilia: Emydidae)

Oxygen consumption by eggs of European pond turtle was determined at two constant incubation temperatures of 25 and 28°C during the second half of embryogenesis. During development at both temperatures, the rate of oxygen consumption initially increased to remain constant during the last quarter of embryogenesis. The difference between the rates of oxygen consumption at these temperatures decreased during the studied period. The coefficient Q₁₀ for the rate of oxygen consumption decreased from 9 to 1.7. At an incubation temperature of 28°C, the changes in the rate of oxygen consumption in response to a short-term temperature decrease to 25°C or increase to 30°C depended on the developmental stage and were most pronounced at the beginning of the studied period. During late embryonic and first 2.5 months of postembryonic development, the rate of oxygen consumption did not significantly differ after such temperature changes. The regulatory mechanisms formed during embryonic development are proposed to maintain the level of oxygen consumption during temperature changes.     

卵形鲳鲹胚胎及早期仔鱼耗氧量的研究

运用SKW-3微量呼吸仪对卵形鲳鲹(Trachinotus ovatus)胚胎和早期仔鱼的耗氧量进行测定,研究温度、盐度及pH的变化对胚胎耗氧量和Cu²⁺、Cd²⁺等重金属离子对早期仔鱼的耗氧量的影响。结果表明:在(25±0.5)℃条件下,卵形鲳鲹胚胎和早期仔鱼的耗氧量均随着发育时间的延长总体上呈上升的趋势,胚胎耗氧量在出膜前达到最大值,其中以原肠期和出膜期耗氧量变化最为显著。胚胎耗氧量随着温度、盐度、pH的增大而逐渐升高,在水温25℃、盐度35和pH为8时耗氧量到达最大值,随后逐渐减小。随着Cu²⁺浓度的升高,早期仔鱼耗氧量呈先增大后减小,在0.01mg·L^-1时耗氧率最大:胚胎耗氧量随着Cd²⁺浓度的升高而逐渐降低。     

The effects of temperature changes on the oxygen consumption of juvenile Chinese shrimp Fenneropenaeus chinensis Osbeck

The effects of temperature changes on oxygen consumption of Chinese shrimp (Fenneropenaeus chinensis Osbeck) were studied. The response of oxygen consumption to a temperature rise was conformed to partial metabolic compensation. No compensatory response was observed at lower temperature. A sudden temperature increase by 12 °C resulted an overshoot in oxygen consumption in shrimp adapted to 19 °C, while a sudden decrease by 12 °C in shrimp adapted to 19 °C resulted in an undershoot in oxygen consumption. The shrimp adapted to 31 °C responded with an undershoot in oxygen consumption when a sudden temperature drop by 12 °C occurred. But overshoot in oxygen consumption did not occur when the shrimps were transferred back from 19 to 31 °C. The amplitude of oxygen consumption was reduced in shrimp during the process of acclimation to the temperature diel fluctuation. After the shrimp had adapted to the temperature fluctuation, the daily mean oxygen consumption of shrimp at diel temperature fluctuation from 24 to 30 °C was significantly lower than those adapted to the constant temperature at 27 °C (P<0.05). The decrease in metabolic rate may account for the increase in the growth rate of shrimp at a diel fluctuating thermal regime.     

Design, operation, and modeling of a membrane photobioreactor to study the growth of the Cyanobacterium Arthrospira platensis in space conditions

A membrane photobioreactor was designed, implemented and used to grow the cyanobacterium Arthrospira platensis PCC 8005 in batch mode. Growth was followed directly by monitoring optical density and indirectly by measuring pressure increase due to the oxygen produced and separated from the liquid phase by diffusion through a hydrophobic membrane, and pH increase due to carbon consumption. When the pressure attained an upper limit, valves opened automatically, and the oxygen in the gas chamber was flushed out with nitrogen. As expected, two growth phases were observed, a short exponential phase followed by a linear phase, indicating limitation by light transfer. Growth rate during the second phase was measured easily and accurately, and consistency of optical density, pressure and pH data values was checked using a model of the system. Pressure measurement was found best suited to monitoring and measuring growth rate in space in terms of accuracy, precision and reliability.     

Kinetics of Low-Temperature Oxidation of Enzymatic Lignin from Pine Wood (Pinus silvestris) in an Aqueous Alkaline Medium

The kinetics of oxidation of the enzymatic lignin from pine wood (brown rotted wood) by oxygen in an aqueous alkaline medium at 90–160°C was investigated. It was established that the vanillin yield increased gradually with the temperature increase in this range from 3.4 to 5.6 wt % with respect to lignin. The observed activation energy of the process of oxygen consumption varies in the range 6–19 kJ/mol depending on the process conditions. The process order with respect to oxygen pressure calculated from the rates of O₂ consumption during the first two hours of oxidation at 90–120°C is 1.02 ± 0.05. The low value of activation energy of the process as well as the first order in oxygen indicates a diffusion-controlled process under these conditions. The kinetic data demonstrate that the role of degenerate chain branching processes increases with the increase in the degree of oxidation as a result of decomposition of the hydroperoxides formed. The hydroperoxide decomposition during oxidation in quantity of more than 16 mol % with respect to the initial lignin was registered using a volumetric method based on the oxygen release. The main causes and features determining the monotonically increasing function of the dependence of the selectivity of lignin oxidation to aromatic aldehydes on temperature were discussed.

     

Gas Exchange of Algae: II. Effects of Oxygen, Helium, and Argon on the Photosynthesis of Chlorella pyrenoidosa

Changes in the oxygen partial pressure of air over the range of 8 to 258 mm of Hg did not adversely affect the photosynthetic capacity of Chlorella pyrenoidosa. Gas exchange and growth measurements remained constant for 3-week periods and were similar to air controls (oxygen pressure of 160 mm of Hg). Oxygen partial pressures of 532 and 745 mm of Hg had an adverse effect on algal metabolism. Carbon dioxide consumption was 24% lower in the gas mixture containing oxygen at a pressure 532 mm of Hg than in the air control, and the growth rate was slightly reduced. Oxygen at a partial pressure of 745 mm of Hg decreased the photosynthetic rate 39% and the growth rate 37% over the corresponding rates in air. The lowered metabolic rates remained constant during 14 days of measurements, and the effect was reversible after this time. Substitution of helium or argon for the nitrogen in air had no effect on oxygen production, carbon dioxide consumption, or growth rate for 3-week periods. All measurements were made at a total pressure of 760 mm of Hg, and all gas mixtures were enriched with 2% carbon dioxide. Thus, the physiological functioning and reliability of a photosynthetic gas exchanger should not be adversely affected by: (i) oxygen partial pressures ranging from 8 to 258 mm of Hg; (ii) the use of pure oxygen at reduced total pressure (155 to 258 mm of Hg) unless pressure per se affects photosynthesis, or (iii) the inclusion of helium or argon in the gas environment (up to a partial pressure of 595 mm of Hg).     

Biphasic oxygen kinetics of cellular respiration and linear oxygen dependence of antimycin A inhibited oxygen consumption

Oxygen kinetics in fibroblasts was biphasic. This was quantitatively explained by a major mitochondrial hyperbolic component in the low-oxygen range and a linear increase of rotenone-and antimycin A-inhibited oxygen consumption in the high-oxygen range. This suggests an increased production of reactive oxygen species and oxidative stress at elevated, air-level oxygen concentrations. The high oxygen affinity of mitochondrial respiration provides the basis for the maintenance of a high aerobic scope at physiological low-oxygen levels, whereas further pronounced depression of oxygen pressure induces energetic stress under hypoxia.     

Effects of substance P on intestinal circulation and oxygen consumption

The effects of intra-arterial administration of substance P upon intestinal blood flow, oxygen consumption, intestinal motor activity, and distribution of blood flow to the compartments of the gut wall were measured in anesthetized dogs. Blood flow to the segment of distal ileum was measured with an electromagnetic blood flow meter and A-VO2 was measured spectrophotometrically. Oxygen uptake was calculated as the product of A-VO2 and total blood flow. The clearance of 86Rb was measured to estimate the density of the perfused intestinal capillaries. Changes in blood flow distribution were estimated from the distribution of radiolabeled microspheres. Motor activity was monitored from changes in intraluminal pressure. Substance P induced a dose-related increase in intestinal blood flow, oxygen consumption, and intestinal motor activity. A significant increase in 86Rb clearance and increase in blood flow to the muscles was also observed. The results of these studies indicate that substance P relaxes intestinal arterioles and precapillary sphincters thereby inducing intestinal hyperemia and increased oxygen consumption. These changes, at least in part, might be due to the increased intestinal motility with enhanced metabolic demands of the muscularis for oxygen.     

The respiratory metabolism of a lizard (Lacerta vivipara) in supercooled and frozen states

We investigated the respiratory metabolism of the overwintering lizard Lacerta vivipara while in either supercooled or frozen states. With a variable pressure and volume microrespirometer and a chromatograph, we show that the oxygen consumption of the supercooled animals showed a nonlinear relationship with temperature and an aerobic metabolism demand between 0.5 and -1.5 degrees C. A significant increase in the respiratory quotient (RQ) values indicated an increasing contribution by the anaerobic pathways with decreasing temperature. In the frozen state, two phases are easily detectable and are probably linked to the ice formation within the body. During the first 5-6 h, the animals showed an oxygen consumption of 3.52 +/- 0.28 microl. g(-1). h(-1) and a RQ value of 0.52 +/- 0.09. In contrast, after ice equilibrium, oxygen consumption decreased sharply (0.55 +/- 0.09 microl. g(-1). h(-1)) and the RQ values increased (2.49 +/- 0.65). The present study confirms the fact that supercooled invertebrates and vertebrates respond differently to subzero temperatures, in terms of aerobic metabolism, and it shows that aerobic metabolism persists under freezing conditions.