Effects of starvation on oxygen consumption, ammonia excretion and biochemical composition of the hepatopancreas on adult males of the False Southern King crab Paralomis granulosa (Crustacea, Decapoda)

Adults of the False Southern King crab, Paralomis granulosa, were starved between 0 and 12 days to evaluate the impact of fasting on the oxygen consumption, nitrogen excretion, O/N ratio and changes on biochemical composition of the hepatopancreas. During the experiment, no mortalities were recorded; physiological changes were detected after 6 days of fasting with an increase of nitrogen excretion (p<0.05). After 9 days of starvation, the crabs showed a maximum decrease in the lipid content (4.3+/-1.2%, p<0.05), accompanied by an increase in oxygen consumption (53.1+/-10.9 microg O2 h(-1) g(-1)). The lowest O/N ratio was detected after 6 days (6.4+/-4.8) and the highest after 12 days of fasting (38.1+/-20.4), indicating that initially crabs utilized proteins as source of energy , followed by lipids. Moreover, after 12 days, there was a significant increase in the hepatosomatic index (HI) and total lipid content (9.7+/-1.0%, p<0.05), which could be associated with the re-absorption of other tissues to the hepatopancreas. Our results provide new information on this species that shows a different pattern of adaptation for each period of starvation and a good correlation between physiological and biochemical parameters. The ability to withstand and recover from periods of nutritional stress is an important adaptation for survival of any organism that must sporadically endure periods of limited food supply.     

Metabolic responses of the white shrimp, Penaeus vannamei, to ambient ammonia

Juvenile shrimp were individually exposed during 24 h to 0.007 (control), 0.36, 1.07, and 2.14 mmol/l total ammonia-N at 28 degrees C and 39 ppt salinity. After 22 h of ammonia-N exposure, oxygen consumption was measured for 2 h, and then hemolymph, hepatopancreas, and muscle tissues were sampled. Oxygen consumption, and levels of lactate and glycogen in the hepatopancreas increased significantly at the highest ammonia-N concentration. Concentration of oxyhemocyanin, acylglycerol, and cholesterol in hemolymph, and lactate in muscle decreased significantly in the group exposed to the highest ammonia levels. The changes observed in hemolymph and tissue metabolic fuels suggest a reduced use of carbohydrate through anaerobic metabolism and an increase in the use of lipids to satisfy the metabolic demand.     

Effect of temperature on the myoglobin-facilitated transport of oxygen in skeletal muscle.

An analysis of thermal effects on the facilitative transport of oxygen in skeletal muscle fibers is presented. Steady-state mass and energy transport balances are written and solved analytically or numerically using a finite-difference procedure. It is shown that no significant spatial thermal gradients exist due to internal reactions or bulk conduction effects across a muscle fiber. At typical muscle conditions, it is predicted that increased global temperature reduces the fraction of oxygenated myoglobin, increases local oxygen concentrations, and increases the percentage of oxygen flux attributed to oxy-myoglobin. The maximum supportable oxygen consumption rate, mO2max, is defined as the highest consumption rate sustainable without developing anoxic regions at the center of the fiber. By considering only temperature sensitive effects within fibers, mO2max is found to increase slightly with temperature at low temperatures. This increase is due to thermal effects on the diffusion coefficients as opposed to effects associated with the kinetics of the myoglobin-oxygen reaction. If the simulations include the temperature effect associated with oxygen solubility in blood plasma, mO2max decreases with temperature. A sensitivity analysis was performed by varying the values of relevant parameters. The maximum consumption rate was least affected by parameters associated with the kinetic and equilibrium constants and most affected by the diffusion coefficients and the concentration of myoglobin.     

Metabolic responses of the white shrimp, Penaeus vannamei, to ambient ammonia

Juvenile shrimp were individually exposed during 24 h to 0.007 (control), 0.36, 1.07, and 2.14 mmol/l total ammonia-N at 28°C and 39 ppt salinity. After 22 h of ammonia-N exposure, oxygen consumption was measured for 2 h, and then hemolymph, hepatopancreas, and muscle tissues were sampled. Oxygen consumption, and levels of lactate and glycogen in the hepatopancreas increased significantly at the highest ammonia-N concentration. Concentration of oxyhemocyanin, acylglycerol, and cholesterol in hemolymph, and lactate in muscle decreased significantly in the group exposed to the highest ammonia levels. The changes observed in hemolymph and tissue metabolic fuels suggest a reduced use of carbohydrate through anaerobic metabolism and an increase in the use of lipids to satisfy the metabolic demand.     

Respiratory responses and blood sugar level of the crab, Barytelphusa cunicularis (Westwood), exposed to mercury, copper and zinc.

Barytelphusa cunicularis (Westwood), a freshwater crab was exposed to mercuric chloride, copper sulphate and zinc sulphate from 0 to 12 hr and the oxygen consumption of the animal was measured in order to study the stress caused by these heavy metals. Normal oxygen consumption was affected by the three heavy metals. Similarly, crabs exposed to sublethal concentrations of the same pollutants for 24, 48, 72 and 96 hr showed an elevation in the blood sugar level with a maximum increase at 48 hr. The results indicate a switch towards glycolysis in order to overcome the anaerobic stress caused by the heavy metals.     

Rhythmic changes in the activity of neurosecretory cells of the scorpion, Heterometrus fulvipes (C. Koch)

Changes in the activity of the neurosecretory cells in the cephalothoracic nerve mass (CTNM) of the scorpion, Heterometrus fulvipes (C. Koch) was studied over a 24-h period under natural light-dark cycles. Cytological and cytometric observations revealed that the first 3 groups of type 'A' cells in the sub-oesophageal ganglion of CTNM evidenced ultradian variations in their activity. Two peaks were seen in the activity of these neurosecretory cells, at 12(00) and 00(00). It is inferred that the cells show a biphasic rhythm in the synthesis of two different principles possibly having antagonistic effects on the central nervous system.     

Susceptibility of urea and uric acid levels to neurohormone influence in the freshwater pulmonate,lymnaea acuminata

Effects of pooled ganglionic extract on the urea and uric acid levels from blood, hepatopancreas, mantle and kidney of the pulmonate L. acuminata have been analysed. Blood urea and mantle uric acid were significantly (P<0.005 and P<0.05 respectively) increased following injection with pleuroparietalpedal-visceral (PPPV Complex) ganglia homogenate within 2 hrs. On the contrary hepatopancreas urea and kidney uric acid levels were significantly (P<0.00) lowered. Cerebral ganglia homogenate and boiled extract of PPPV complex did not provoke any significant change in urea and uric acid levels. It is advocated that (a) neurohormone(s) which is (are) heat-labile and originate from the PPPV complex, influence(s) the nitrogen end-products in these snails.     

Calcium regulation in the freshwater snail indoplanorbis exustus during shell repair

A piece of shell was removed from Indoplanorbis exustus without injuring the mantle. Calcium was estimated from hepatopancreas, foot, mantle and shell at different intervals. It was observed that the calcium content of the shell was directly proportional to that in the mantle. The calcium content in the hepatopancreas showed an increase within 6 hours of injury and then decreased upto 144 hours. The foot showed an increase in calcium in the first 6 hours and reached a maximum after 96 hours after injury. The calcium, in the mantle also increased within 6 hours after injury, which increase exceeded that from the foot.     

Acute toxicity of cadmium and copper in hepatopancreas cells from the Roman snail (Helix pomatia)

The toxic effects of cadmium (Cd) and copper (Cu) on cellular metabolism and cell morphology were investigated in isolated hepatopancreas cells from the Roman snail (Helix pomatia). Cell viability was unaffected during 1 h of incubation with 100 microM Cd, but was significantly reduced from 93% in controls to 87% and 85% with 100 microM Cu and 500 microM Cd, respectively. The adverse effect of 500 microM Cd on cell viability was not observed in cells isolated from Cd pretreated snails. Oxygen consumption remained constant in the presence of 100 microM Cu but was inhibited by 38% after 1 h of exposure to 500 microM Cd. Hepatopancreas cells showed enhanced formation of reactive oxygen species when exposed to 100 microM Cu, but not in the presence of Cd. Morphologically, an increase in cell volume of Cd-exposed cells was noted, while cell membrane bleb formation was induced by both metals. The latter may have been induced by metal effects on the actin filamentous network of the cells which showed distinct actin-staining within the blebs at the cell surface. Overall, our data indicate that both Cd and Cu are acutely toxic for hepatopancreas cells form the Roman snail with Cu being more toxic than Cd.     

Effects of noradrenaline and the blood perfusion rate on the oxygen consumption of intact and isolated muscles of cold-acclimated rats

The authors studied the effect of the blood perfusion rate and of noradrenaline (NA) on the oxygen consumption of the isolated hind limb and on the partly - and vascularly completely - isolated cranial gracilis muscle of cold-acclimated rats. Oxygen consumption of the limb was stimulated by a raised perfusion rate together with growth of the oxygen extraction coefficient and by NA, which also raised oxygen consumption when the perfusion rate was constant. Oxygen consumption of the partly isolated muscle was likewise stimulated by a raised perfusion rate, but without a simultaneous increase in the oxygen extraction coefficient. In the vascularly completely isolated muscle, a raised perfusion rate had only a transient stimulant effect on oxygen consumption. In the partly and the completely isolated muscle, NA raised the arteriovenous difference in the blood oxygen content and organ resistance independently of each other. The calorigenic effect of NA, which was determined by the ratio of the two effects, did not exceed 34% above the resting level. The conclusions that the thermogenesis of resting muscle can be controlled by the blood flow on the basis of a mechanism other than the limitation of oxygen or substrates supply, and that NA acts independently of oxygen extraction from the blood and of the blood flow, show the blood flow to be a mechanism at organ level, which participates in the control of nonshivering thermogenesis in skeletal muscle.     

Comparison of the effects of several endotoxin preparations on body temperature and metabolic rate in the rat

The effects of several bacterial endotoxins on body temperature and resting oxygen consumption (VO2) were compared in normal rats. Low doses (0.05 mg/kg, i.m.) of 0127:B8 phenol-extracted endotoxin caused significant increases in both parameters. Maximal febrile responses (+1.6 degrees C) occurred at a dose of 0.05 mg/kg, but higher doses produced smaller effects. The maximal increase in VO2 (17%) occurred at doses of 0.5-1.0 mg/kg. A TCA extract of the same strain of endotoxin elicited a similar pattern of responses but was less potent than the phenol extract, whereas another endotoxin 026:B6 (TCA extract) was much less potent. The data illustrate the importance of constructing dose-response curves when comparing different endotoxins and indicate that in the rat, oxygen consumption provides a useful index of the response to pyrogens.     

Acute cold exposure and the metabolism of glucose and some of its precursors in the liver of the fed and fasted sheep.

Measurements of total body oxygen consumption, visceral and hepatic blood flow, oxygen consumption, exchanges of amino acids, lactate, pyruvate and glucose were made on sheep fed 3--6 h or 21 h before the experiment and exposed for 3 h to a neutral environment (15 degrees C) or a cold environment (0.5 to 4 degrees C with clipped coat and wind speed 2 m.s-1). Recent feeding significantly increasedd the total oxygen consumption and the oxygen consumption of the viscera and liver. No general release of amino acids from the viscera or uptake by the liver after feeding was detected although the arterial plasma concentration of essential amino acids did increase significantly after feeding. The plasma concentration of most non-essential amino acids also increased except that of glycine, which decreased significantly. Cold exposure increased the total oxygen consumption and reduced the respiratory quotient significantly. Release of amino acids from the viscera was stimulated by cold exposure. There was a variable increase in the hepatic uptake of lactate and alanine when the sheep were fasted and cold-exposed. The liver's glucose output doubled and the blood (arterial) glucose concentration significantly increased in the cold.     

Intestinal blood flow and oxygen consumption

In this study, we examined the effects of both pharmacologically and mechanically induced increases in intestinal blood flow on intestinal oxygen consumption. Intraarterial infusions of prostacyclin (1-20 ng X kg-1 X min-1) significantly increased both blood flow and oxygen consumption under free flow conditions. However, the increase in oxygen consumption appears to be due to the corresponding increase in blood flow rather than a direct effect of prostacyclin on intestinal metabolism. This conclusion is supported by the finding that a mechanically induced increase in intestinal blood flow (60%) can also produce an increase in intestinal oxygen consumption (24%). These findings support the hypothesis that intestinal oxygen consumption is flow-dependent over a wide range of blood flows.     

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 responses of Carcinus maenas (L.) to changes in environmental salinity

Exposure of Carcinus to a reduction in salinity is accompanied by an increase in oxygen consumption. The highest rates of oxygen consumption are found during the first 2–3 h after a reduction in salinity, after which oxygen consumption then declines, but to a higher than ‘normal’ level which is maintained throughout the period of exposure to low salinity. This augmented rate of oxygen consumption persists even after 3–4 days in water of reduced salinity and indicates that the respiratory rate of Carcinus does not acclimate rapidly to reduced salinity. The increased oxygen consumption is associated with an increase in ventilation volume resulting from an increase in the rate of beating of the scaphognathites, while oxygen utilization remains at a low level. Since the oxygen-transporting properties of the blood of Carcinus show little change under conditions of reduced salinity, the increased oxygen demand of the tissues is met by a rise in cardiac output resulting mainly from an increase in heart rate.     

Measurements of oxygen consumption in Mytilus edulis during exposure to, and recovery from, high sublethal concentrations of formaldehyde, benzene and phenol.

1. The rate of oxygen consumption has been monitored continuously in M. edulis during acute exposure to high sublethal concentrations of formaldehyde, phenol and benzene and subsequent recovery periods of 96 hr. 2. The results are discussed in relation to changes in the electrochemical potential difference of sodium, the content of ATP and the tissue concentration of strombine. 3. After exposure to benzene and phenol, an increase in the rate of oxygen consumption that could not be explained by oxygen debt from the exposure period was observed. 4. Depression of the rate of oxygen consumption after exposure to formaldehyde may be explained by a reduced ability to extract oxygen from the water. 5. The pattern of oxygen consumption and behavioural responses, as well as the combined changes in the biochemical markers, were distinctly different in the three cases.     

Individual specifics of oxygen consumption by the human organism in hypoxia

Influence of hypoxia on a human organism was studied with the help of hypoxic gas mixtures (HGM) in the first series with 14 % content of oxygen in nitrogen (n = 6), in the second one--with 12 % (n = 10) in the third one--with 8 % (n = 14). Hypoxic exposition in all the series was 25 min. In 6 subjects engaged in all the 3 series, physical working capacity was assessed in two-step test on a veloergometer. In all the 3 series, oxygen consumption by the organism some time after the start of the hypoxic action exceeded the background normnoxic level. Maximal value of this excess on the average was the highest in HGM-12 series--40 +/- 12 %. Maximal increase of the respiration and central blood circulation velocity was the highest in HGM-8 series, 90 +/- 24 and 25 +/- 16 % respectively. Analysis of the EEG parameters, oxygen saturation and rheoencephalographic data indicates the probability of the cerebral metabolic rate of oxygen during hypoxia to beein normal (in most subjects) and even increased (in some subjects). In 3 subjects of 6, whose physical working capacity was assessed, maximal increase of oxygen consumption was observed in HGM-8 series--105 +/- 34 %. Their physical working capacity was higher than of those subjects, who showed maximal increase of oxygen consumption in HGM-12 series. Analysis of increase in oxygen consumption (paradoxical under hypoxic conditions) doesn't allow to ascribe it wholly to an increase of the respiration and central blood circulation. Obviously, the increase of oxygen and energy expenditures for biochemical adaptation to hypoxia, which has common features with adaptation to physical activity plays an important role under hypoxia.     

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.     

Mechanism of death at high temperatures in Helix and Patella

In Patella vulgata and Helix aspersa which had been killed by exposure to high temperatuers, the rates of oxygen consumption of gill, foot muscle and hepatopancreas are remarkably steady when measured at lower temperatures, although the absolute levels are in some cases different from normal animals. These tissues are thus substantially metabolically intact in heat dead individuals. In Helix there is a fall in blood sodium and a rise in blood potassium during heat death. In Patella there is a marked rie in blood Na⁺ and a consequent disturbance of the Na⁺/K⁺ ratio. These ionic disturbances are thought to be a prime cause of heat death. The significance of the results is discussed.     

Physiological roles of free D- and L-alanine in the crayfish Procambarus clarkii with special reference to osmotic and anoxic stress responses

Under hyper-salinity stress from freshwater to 17 and 25 ppt seawater, red swamp crayfish Procambarus clarkii largely accumulated D- and L-alanine together with glycine, L-glutamine, and L-proline in both muscle and hepatopancreas. The increases of D- and L-alanine in muscle were the highest in all amino acids and reached 6.8- and 5.4-fold, respectively, from freshwater to 25 ppt seawater. These results indicate that both D- and L-alanine are the most potent osmolytes for intracellular isosmotic regulation in crayfish as well as other crustaceans thus far examined. Under anoxia stress below 0.1 mg/l dissolved oxygen for 12 h and subsequent recovery in normoxia for 12 h in freshwater, 17 and 25 ppt seawater, muscle ATP decreased dramatically in all salinity levels and almost depleted in seawater. Along with the decrease of muscle glycogen level, the significant increase of L-lactate was found in muscle, hepatopancreas, and hemolymph for each salinity level, suggesting the transport of L-lactate from muscle into hepatopancreas via hemolymph. Under anoxia, D- and L-alanine also largely increased in both muscle and hepatopancreas for each salinity level. The increase was much higher in seawater than in freshwater. Thus, both D- and L-alanine are possible to be anaerobic end products during prolonged anaerobiosis of this species.