Effect of hibernation on liver and kidney metabolism in 13-lined ground squirrels

• 1.1. Metabolic rates and adenine nucleotide content of liver and kidney from hibernating ground squirrels were measured and compared to rats to study the biochemical adaptation to hibernation.
• 2.2. High rates of renal and hepatic gluconeogenesis were observed in squirrels, particularly from propionate and glycerol compared to rat.
• 3.3. During hibernation and starvation soluble phosphoenolpyruvate carboxykinase activity was increased in both liver and kidney.
• 4.4. Although metabolic rates are decreased during hibernation the results suggest that the enzymic complement is maintained at high activity even during torpor.

     

Thermoreceptor distribution in different skin layers and its significance for thermoregulation

• 1.1.|The activity pattern of 50 cold receptors of the rabbit nose back skin was investigated.
• 2.2.|The latency of the response of individual cold receptors to identical cold stimuli varied between 0.8 ± 0.3 to 29.4 ± 4.5 s; maximal firing rates are attended after 5.5 ± 0.5 to 72.2 ± 6.2 s. Characteristic phasic responses are only demonstrated by short latency receptors.
• 3.3.|The results suggest that cold receptors are distributed throughout the skin of the rabbit's nose.
• 4.4.|Changes of temperature gradients between different skin layers were measured at different ambient temperatures.
• 5.5.|It is suggested that cold receptors might indicate heat flow through the skin.

     

Reduced muscle protein breakdown in septic rats following treatment with interleukin-1 receptor antagonist

• 1.1. The role ofinterleukin-1 (IL-1) in sepsis-induced muscle proteolysis was assessed by treating septic rats with recombinant IL-1 receptor antagonist (rIL-Ira).
• 2.2. In initial experiments, we tested the effectiveness of IL-Ira in preventing muscle proteolysis induced by administration of IL-1.
• 3.3. When normal rats were treated with rIL-α (three intraperitoneal doses of 100 μ g/kg body weight each over 16 hr), total and myofibrillar muscle protein breakdown rates, measured as release oftyrosine and 3-methylhistidine, respectively, by incubated extensor digitorum longus muscles, were significantly increased.
• 4.4. This metabolic response to IL-α was completely abolished by rIL-Ira, administered as three intraperitoneal doses of 3 mg/kg body weight each over 16hr.
• 5.5. In subsequent experiments, sepsis was induced in rats by cecal ligation and puncture (CLP); non-septic rats were sham-operated.
• 6.6. Treatment of septic rats over 16hr with a total dose of 25mg/kg body weight of rIL-Ira reduced, but did not normalize, the increased muscle protein breakdown rates seen during sepsis.
• 7.7. When the dose of rIL-Ira was more than doubled and given as a constant infusion at a rate of 4.2 mg/kg body weight/hr for 16 hr, the increased rate of muscle proteolysis in septic rats was normalized.
• 8.8. The present study offers the first direct evidence that IL-1 is involved in the regulation of muscle proteolysis during sepsis.

     

The mechanism of calcium-dependent activation of respiration of liver mitochondria from hibernating ground squirrels,Citellus undulatus

• 1.1. It is shown that Ca²⁺-dependent activation of respiration of liver mitochondria from hibernating ground squirrels is accompanied by mitochondrial swelling.
• 2.2. The swelling of mitochondria from hibernating ground squirrels, as well as the activation of mitochondrial respiration, is precluded by cyclosporin A, p-bromphenacylbromide and oligomycin. Carboxyatractiloside, on the contrary, under these conditions favors the swelling and the acceleration of respiration.
• 3.3. It was concluded that Ca²⁺-dependent activation of hibernating ground squirrel liver mitochondrial respiration resulted from the appearance of a non-specific permeability pathway and from swelling of mitochondria.

     

Increased muscle glucose uptake in response to chronic glyburide treatment is not related to changes in glucose transporter (GLUT4) protein

• 1.1. The mechanism of action of glyburide (a sulfonylurea) on muscle has been investigated by measuring glucose uptake and glucose transporter (GLUT4) protein levels after chronic glyburide treatment.
• 2.2. A dietary induced insulin resistant rat model (4 wk of high-fat, high-sucrose feeding) was given glyburide (2mg/kg/day) for 10 days and glucose uptake was measured in a perfused hindquarter preparation.
• 3.3. Protein levels of the GLUT4 glucose transporter were determined by Western analysis.
• 4.4. After 7 days of treatment, rats fed glyburide had lower blood glucose concentrations 2 hr (72 ± 5 vs 103 ± 12 mg/dl) and 24 hr (97 ± 7 vs 123 ± 7 mg/dl) after glyburide administration with no difference in serum insulin levels compared to vehicle treated animals.
• 5.5. Glucose uptake was approx doubled in basal state (0 insulin) in response to glyburide (2.8 + 0.4 vs 1.7 ± 0.2μ mol/g per hr).
• 6.6. Maximal insulin (100 nM) stimulated glucose uptake tended to be higher in the glyburide treated group, but did not reach statistical significance (8.0 ± 0.7 vs 7.0 ± 0.6 μmol/g per hr).
• 7.7. Western analysis revealed no significant effect of glyburide on the GLUT4 protein level in skeletal muscle.
• 8.8. These results suggest that glyburide alters glucose uptake through some mechanism other than alterations in the level of the GLUT4 glucose transporter protein.

     

The effect of dietary protein level and ration level on excretion of ammonia in common carp,Cyprinus carpio

• 1.1. Nitrogenous excretion in the form of ammonia was determined in common carp of 65.0 ± 8.0 g body weight in metabolism chambers. The fish were fed with 20, 35 and 50% dietary protein at 1, 2 and 3% body weight per day ration level.
• 2.2. Nitrogenous excretion as a percentage of ingested food increased with an increase of dietary protein but decreased with an increase of ration level.
• 3.3. The energy lost in excretion ranged from 4.19% with 20% dietary protein at 3% ration level to 8.74% with 50% dietary at 1% ration level.

     

Changes in the activity of the adrenal cortex in fasted echidnas (Tachyglossus aculeatus) exposed to low ambient temperatures

• 1.1. The adrenal cortex is necessary for survival of echidnas at low ambient temperatures. In this study, adrenal gland activity was investigated in echidnas exposed to 2 days of cold (14°C) and fasting, alternating with 2 days at room temperature and feeding ad lib.
• 2.2. In the cold. 2.75 ± 0.29% (SD) of the initial body weight was lost daily. Plasma amino acid concentration did not change while glucose concentration decreased from 2.6 ± 0.3 to 1.5 ± 0.3 mmol/l with consecutive sessions of cold.
• 3.Plasma concentrations of corticosterone (7.2 ± 1.4 nmol/l) and cortisol (4.4 ± 1.9 nmol/l) were unchanged by repeated cold exposure. However, the adrenal response to ACTH stimulation decreased and the clearance of corticosteroids increased after cold exposure.
• 4.It was concluded that exposure to cold increases the utilization of glucocorticoids and decreases the capacity for their biosynthesis.

     

The energetics of shedding: Energy content of snake skin

• 1.1. The weight and energy content of sloughed skins of 92 individual snakes of 22 different species in three families were measured.
• 2.2. Weight and total energy content of shed skins were highly correlated with body weight.
• 3.3. The heat of combustion (kJ/g) of sloughed skins varied significantly among families and was higher in species having unkeeled scales than in those with keeled scales.
• 4.4. The presence of keels significantly affected weight of skins, even when skin weight is adjusted for covariance with body weight.
• 5.5. Neither body weight nor ambient temperature significantly affected the heat of combustion of sloughed skins.
• 6.6. The energy content of shed skin, expressed as a proportion of daily metabolism, decreased with ambient temperature, but the effect is minimized in large snakes.
• 7.7. Small snakes expended relatively less energy in sloughed skins than large snakes when the expenditure is expressed in terms of total daily metabolized energy.

     

Lethal body burden of triphenyltin chloride in fish: Preliminary results

• 1.1. Guppies exposed to several triphenyltin chloride (TPTC) concentrations in water died as soon as a body burden of 20 ± 10 nmol/g fish was reached.
• 2.2. Accumulation of TPTC during exposure in acute toxicity experiments can be predicted by using the kinetic parameters of TPTC.
• 3.3. The lethal body burden is two orders of magnitude lower than for narcotic organic compounds such as chlorobenzenes.

     

Differential post-receptor responses of adenylate cyclase in white and brown adipose tissue membranes of rats fed high-energy diets

• 1.1. Adenylate cyclase activity was determined in membranes of white and brown adipose tissue (WAT and BAT, respectively) from rats fed a high-energy diet (EXP group) vs those fed a nutritionally balanced one (CON group).
• 2.2. The isoproterenol- and guanine nucleotide-induced adenylate cyclase activity in WAT membranes of EXP rats was lower than that in CON rats.
• 3.3. Relative adenylate cyclase activity in like treated BAT membranes was higher in EXP than in CON rats.
• 4.4. It is concluded that feeding high-energy diets to rats induces similar post-receptor modifications of adenylate cyclase as found in genetic obese rodents.

     

Anaerobic threshold in rats

• 1.1. The aim of this study was to find out whether the anaerobic threshold (AT) can be estimated in rats running at increasing speed and if so what is the reproducibility of the measurements.
• 2.2. Lactate (LA) concentrations in blood taken from 11 rats were determined during a discontinued, multistage treadmill exercise test repeated four times in each animal.
• 3.3. It was found that blood LA changes vs speed have an exponential pattern with a distinct, rapid rise at the speed above 25 m/min which corresponds to blood LA of approx. 4 mmol/1.
• 4.4. The variation coefficient of the speed at which AT occurred in individual animals ranged between 10 and 20%.
• 5.5. These results offer a potential application of AT determination in the animal studies concerning mechanisms controlling exercise metabolism.

     

Ventilatory rate in the butterfish (Pholis gunnellus) as a consequence of temperature and previous emersion

• 1.1. Observation of ventilation in immersed Pholis gunnellus showed a linear relationship between ventilatory rate and temperature between 8 and 20°C.
• 2.2. At 13°C and after 30 min emersion, ventilatory rate was initially lower than prior to emersion, providing evidence of adequate uptake of O₂ for standard metabolism during the emersion period.
• 3.3. This species has a laterally elongate body form with reduced scales and extensive mucus secretion.
• 4.4. During emersion, gaping behaviour probably exposes the gills and extensively vascularised oesophageal regions to air.
• 5.5. These are considered to be morphological and behavioural adaptations by P. gunnellus, to aerial respiration in the intertidal habitats occupied by this species.

     

An experimental analysis of the metabolic rate and food utilization of northern pike

• 1.1. The metabolism of northern pike (Esox lucius) was determined by oxygen consumption and ration experiments to obtain data for an energy budget analysis.
• 2.2. Metabolic measures of oxygen consumption were most reliable, and were described by the equations: R_met = 27.5 Wt^0.82 at 14°C and R_met = 1.6 Wt^0.97at 2°C.
• 3.3. In addition, conversion efficiency (K₂ = 0.319 ± 0.064) and assimilation efficiency (0.872 ± 0.060) were determined.
• 4.4. Proximate composition of fish under various feeding regimes indicated that energy gain or depletion from the body was due to changes in amount of whole body tissue or body protein, rather than specific utilization or storage of lipid.

     

Properties of the transition from short-term to long-term depression in neurons of Helix pomatia

• 1.1. Synaptic short-term depression could be transferred into long term depression by repetition of series of stimuli.
• 2.2. The transition from short-term depression to long-term depression was blocked by puromycin.
• 3.3. The majority of the transition took place during resting periods between stimulus series.
• 4.4. The initiation of the transition process was 83% completed after 5 min of stimulation.
• 5.5. Short- and long-term depression were quantitatively separated into their two serial sites of origin: afferent axons and synaptic terminals.
• 6.6. Long sequences evoked periods with increased and variable EPSPs not conforming to depression.

     

Hyperosmotic properties of the fluids of the perivisceral coelom and water vascular system of starfish kept under stable conditions

• 1.1. Osmotic measurements were made on the perivisceral coelomic and water vascular fluids of 4 species of northwest Pacific starfish and their stable sea-water media.
• 2.2. Mean levels of both fluids were hyperosmotic in every species, often at statistically significant levels.
• 3.3. For all species combined, mean hyperosmolality (mosmol/kg ± SE) of perivisceral coelomic fluid was 1.49 ± 0.17, and water vascular fluid 6.07 ± 0.74.
• 4.4. The hyperosmotic nature of these fluids contributes to water balance, working in conjunction with madreporitic inflow and other factors.

     

Three digestive tract endocrine peptides and the circannual cycle of body weight in Spermophilus lateralis

• 1.1. Thirty-one male golden-mantled ground squirrels were divided into four physiological groups: low wt summer, medium wt summer, high wt summer and hibernation period. A second group of 10 females was divided into two groups: hibernation period at low T_b and hibernation period during a periodic arousal.
• 2.2. Blood serum, pancreas and antral stomach region were collected from each animal.
• 3.3. The serum was analysed by radioimmunoassay for pancreatic polypeptide immunoreactivity, the pancreas for pancreatic polypeptide and somatostatin immunoreactivity and the antral region of the stomach for gastrin immunoreactivity.
• 4.4. Significant between-stage differences (P < 0.05) were found in serum pancreatic polypeptide concentration and in pancreatic somatostatin content.

     

Measurement of blood flow to osseous tissue in dogs using the radiolabelled microsphere method

• 1.1. The purpose of this study was to examine bone blood flow in various intra- and extra-oral sites.
• 2.2. The radiolabelled microsphere method was utilized to assess osseous blood flow in the following regions of 10 dogs: rib, long bone, and anterior and posterior regions of the maxilla and mandible.
• 3.3. Samples of cancellous and cortical bone were also obtained from each of these regions with the exception of the maxilla and the anterior mandible.
• 4.4. Mean blood flow ranged from 3.71 ±0.81 (SE) ml min.⁻¹ 100 g⁻¹ in the mandibular posterior cortical bone to 22.7±4.66ml min⁻¹ 100 g⁻¹ in the cancellous rib samples.
• 5.5. Blood flow to the cancellous tissue of the rib was significantly greater (P < 0.05 ) than the other tissues with the exception of maxillary posterior bone and cortical rib.
• 6.6. Results from this study indicate that blood flow to the maxillary posterior bone is relatively high, but blood flow in other intraoral osseous sites is significantly less than that of cancellous rib bone.

     

Metabolic roles of carnitine expressed through the carnitine acetyltransferase system in Candida pintolopesii

• 1.1. The carnitine-responsive mutant yeast, Candida pintolopesii ATCC 26014 and the wild type strain (ATCC 22987) were used to investigate the role of carnitine and the carnitine acetyltransferase system.
• 2.2. [³H]l-Carnitine, supplied to the cells, was incorporated into acetylcamitine and [¹⁴C]pantothenate was incorporated into CoA and its derivatives.
• 3.3. Both bioautography and quantitative assays indicated that the relative amounts of CoA and acetylCoA were very different in the mutant and wild type cells.
• 4.4. The wild type yeast maintained an acetylCoA/CoA ratio of 0.33 ± 0.09 indicating that most of the CoA in the cell is in the free CoA form. Carnitine was not required to establish this ratio nor did its presence lower it further.
• 5.5. In contrast, the mutant cells contained a high acetylCoA/CoA ratio (12.8 ± 3.0).
• 6.6. In the mutant cells, carnitine lowered the ratio by decreasing the intracellular acetylCoA concentration and releasing free CoA.
• 7.7. These data indicated that wild type yeast possess an effective mechanism that is not related to the CAT system for regulating the acetylCoA/CoA ratio.
• 8.8. This mechanism appears to be lacking in the mutant. The CAT system decreased the acetylCoA/CoA ratio in the mutant cells but not to the value which is found in the wild type strain.
• 9.9. In both stains of Candida pintolopesii, in the presence of carnitine, an acetylcamitine pool can be created whose concentration exceeds that of acetylCoA.
• 10.10. The intracellular apparent equilibrium constant (K_app) for carnitine acetyltransferase for wild type Candida pintolopesii ATCC 22987 was 0.73 ± 0.12, close to the established value of 0.6, indicating that the CAT system ran close to equilibrium.
• 11.11. The K_app for the CAT system of the carnitine-responsive mutant yeast was 7.7 ± 1.7 indicating that this reaction was not at equilibrium.

     

Lactate dehydrogenase of goldfish red and white muscle in relation to thermal accumulation

• 1.1. Activities of the red and white muscle LDH from 8°C-acclimated goldfish were about three times higher than those acclimated to 28°C.
• 2.2. Isozyme composition and some kinetic properties of the red muscle LDH differed from those of the white muscle enzyme.
• 3.3. The amount of red muscle as well as LDH activity tended to increase during cold acclimation.

     

Utilization of body stores in embryonated ova and larvae of two coregonid species (Coregonus lavaretus L. and C. albula L.)

• 1.1. Developing eggs of whitefish (Coregonus lavaretus L.) and vendace (Coregonus albula L.) were kept at 1–2°C and some eggs taken gradually up to 8°C to provoke mass hatching of embryos.
• 2.2. Wet weight, dry matter and the contents of lipid, protein and ash were measured in fish during the course of experiment.
• 3.3. Dry matter content decreased gradually in whitefish eggs from 15.64 to 11.95% during 1 month at 1–2°C, whereas vendace eggs showed only a slight decrease from 16.27 to 15.53%.
• 4.4. In both species protein content decreased but lipid increased when approaching the natural time of hatching.
• 5.5. During delayed hatching at low water temperatures protein contributes to catabolism, whereas lipid content decreased only in the later phase of the experiment.
• 6.6. Larvae starved for 10 days after hatching lost increasing amounts of dry matter (from 26.1 to 50.3% of body weight) and protein (from 18.7 to 45.9% of body weight) as they remained longer in cold water as embryos.
• 7.7. A correspondence was found between assessment of metabolic utilization of body stores based on chemical analysis of fish body and previous work on oxygen consumption and nitrogen excretion.