Respiratory and blood gas responses in exercising birds

• 1.1. The effects of exercise in birds on changes in body temperature, ventilation, blood gases and air-sac gases are reviewed.
• 2.2. Except in the case of isothermic exercise below the anaerobic threshold, birds hyperventilate during exercise. Exercise hyperventilation is greater at higher exercise intensities and at higher environmental temperatures.
• 3.3. The domestic fowl appears to be a suitable model for the study of physiological responses to exercise in running birds. A prior period of training is necessary to accustom the birds to laboratory procedures.
• 4.4. The possible neural and/or humoral mechanisms controlling exercise hyperpnea are listed. Intrapulmonary hypocapnia seems to exclude the possibility that lung chemoreceptors are responsible for the hyperpnea during exercise, but these receptors probably play a predominant role in the determination of ventilatory pattern.

     

Phosphatidylethanolamine: Ceramide-ethanolaminephosphotransferase activity in synaptic plasma membrane vesicles. Influence of some cations and phospholipid environment on transferase activity. Further proof of its location

• 1.1. Synaptic plasma membrane vesicles (SPMV) from rat brain synthesized ceramide-phosphoethanolamine (SpE), an analogue of sphingomyelin (SpC) from phosphatidylethanolamine (PE) and ceramide.
• 2.2. This reaction was catalyzed by PE: ceramide-phosphotransferase.
• 3.3. The presence of PC did not modify the SpE synthesis and PI and PS at twice PE concentration seemed to be activators; only PG was an inhibitor at all concentrations.
• 4.4. Some cations (Mg²⁺, Mn²⁺) were without effect, while Ca²⁺ increased transferase activity, so was interesting to study.
• 5.5. Transferase was compared with sialidase (external enzyme).
• 6.6. Kinetics other than those already performed by us were undertaken in order to confirm its location.

     

Isolation and characterization of the major phospholipase a2 from the venom of trimeresurus purpureomaculatus (shore pit viper)

• 1.1. The major phospholipase A₂ (PLA-DE4) of the venom of Trimeresurus purpureomaculatus (shore pit viper) has been purified to electrophoretic homogeneity.
• 2.2. The isoelectric point of the purified enzyme was determined to be 4.20, and the mol. wt was 31,700 as estimated by Sephadex G-75 gel filtration chromatography; and 14.000 as estimated by SDS-polyacrylamide gel electrophoresis.
• 3.3. The purified enzyme hydrolyzed phosphatidylcholine (PC) faster than phosphatidylethanolamine (PE), whereas phosphatidylserine (PS) was not hydrolyzed at all (PC > PE > PS = 0). However, in reaction system consisted of mixtures of PC and PS, phosphatidylserine was effectively hydrolyzed by the enzyme.
• 4.4. The phospholipase A₂ exhibited edema-forming activity but not hemolytic, hemorrhagic or anticoagulant activities. It was not lethal to mice at a dosage of 10 μg/g by i.v. route.

     

Myofibril and sarcoplasmic reticulum changes during muscle development: Activity vs inactivity

• 1.1. The purpose of this study was to determine whether biochemical changes of skeletal muscle that occur as a result of exercise in young rats persist into adulthood.
• 2.2. Littermates (10 days old) were assigned to a 3, 6 and 12 week control or training group. In addition, a rest-exercise group (R-E) and exercise-rest (E-R) group were included.
• 3.3. The rest-exercise and exercise-rest rats were maintained for the 12 weeks with the first 6 weeks being either rest or exercise and the condition reversed during the last 6 weeks of the experiment.
• 4.4. Myofibril ATPase activity of rat plantaris increased from the 10d to 12 week animals (P < 0.05). As anticipated, training resulted in a lowered activity at 6 and 12 weeks compared to controls.
• 5.5. The Ca²⁺ uptake and Ca²⁺-ATPase activity of the sarcoplasmic reticulum followed a similar pattern.
• 6.6. With regard to the exercise-rest rats, the myofibril and SR ATPase activities at 12 weeks were comparable to the 12 weeks control rats.
• 7.7. The rest-exercise group approximated the 12 week training group with regard to myofibril and SR ATPase activities (P > 0.05).
• 8.8. The results suggest that the training adaptations that occur during development of skeletal muscle return to normal, when training ceases in the adult rat.
• 9.9. Furthermore, animals that started to train prior to puberty do not have a greater capacity to adapt than animals which initiated training during adulthood.

     

Depressed baroreceptor-cardiac reflex sensitivity during simulated diving in ducks

• 1.1. The baroreceptor-cardiac reflex was examined in unanesthetized ducks at rest and during diving. In ducks breathing air an inverse relationship between mean arterial blood pressure and heart rate was observed over the pressure range from 80cm H₂O to 290cm H₂O.
• 2.2. Increases in pressure were obtained by bolus intravenous injection of phenylephrine (PE) while the hypotension was achieved by intravenous acetylcholine (ACh).
• 3.3. The inverse relation of blood pressure and heart rate was also observed in ducks without pharmacologic intervention.
• 4.4. The baroreceptor-cardiac reflex sensitivity was -3.13 beats/min/cm H₂O in non-diving ducks and fell to -0.96 beats/min/cm H₂O with PE and ACh derived data.
• 5.5. During diving the baroreceptor-cardiac reflex sensitivity was further reduced to —0.48beats/ min/cm H₂O.
• 6.6. This finding indicates that even during the pronounced bradycardia of diving baroreceptor stimulation continues to influence heart rate.

     

The influence of calcium and magnesium on sea bass (Dicentrarchus labrax) intestinal brush border membrane purification and activity

• 1.1. The activity of brush border enzymes (alkaline phosphatase, maltase, sucrase, trehalase, leucine amino peptidase) was higher in purified membranes prepared with calcium. The contamination of these membranes with basolateral membranes was also lower (1.27 for Na-K-ATPase activity ratio).
• 2.2. The extraction of brush border lipids was carried out according to Folch adapted method. Two dimensional thin layer chromatography was used to separate the phospholipidic fractions. Fatty acids of phospholipids were analysed using gas chromatography after acid transmethylation (column SP 2330).
• 3.3. Phospholipids are composed of phosphatidylcholine (PC: 33%), phosphatidylethanolamine (PE: 30%), sphingomyeline (SM: 21%), phosphatidylserine (PS: 14%) and phosphatidylinositol (PI: 2%). 4. PC, PE and PS are characterized by high levels of unsaturated fatty acids (monounsaturated MUFA: 21.5% and polyunsaturated PUFA: 34.9%). The most abundant PUFA belong to the (n-3) family [18:3 (n-3), 20:5 (n-3) and 22:6 (n-3)].
• 4.5. Fatty acids from sphingomyelin of purified membranes have low proportions of PUFA (13.5%) but higher proportions of MUFA (39.5%).
• 5.6. No specific differences were found between calcium and magnesium prepared membranes.
• 6.7. The low content in LPC and the absence of LPE confirmed the absence of major structural lipids transformation during the membrane purification with calcium or magnesium.
• 7.8. Glycine transport was measured during 10 sec at different temperatures using the rapid filtration technique. Glycine transport was higher with Na⁺ than with K⁺. In the presence of Na⁺, this transport increases with temperature.
• 8.9. Arrhenius curves were mono phasic without obvious breakpoint and indicated no phase transition in the lipid bilayer.
• 9.10. A significant Na⁺ dependent glycine transport has been characterized at low temperatures (0°C) which suggests a possible role of membrane polyunsaturated fatty acids in the control of glycine transport.

     

Heart rate and its cholinergic control in the sole (Solea vulgaris), acclimatized to different temperatures

• 1.1. The effects of thermal acclimatization at 10 and 24°C on heart rate were investigated on unrestrained soles (Solea vulgaris).
• 2.2. The sensitivity of heart rate to temperature changes induced by temperature acclimatization was higher in cold-acclimatized than in warm-acclimatized soles.
• 3.3. Heart rate of cold-acclimatized fish to temperature changes was not affected by blocking the vagal tone with atropine.
• 4.4. After atropine treatment the ability of heart rate to show thermal compensation decreased in warm-acclimatized soles.
• 5.5. It is suggested that the vagus nerve can function differently at different temperatures.

     

Changes in plasma glucose and lipid concentrations during treadmill exercise in domestic fowl

• 1.1. Plasma glucose, non-esterified fatty acid, triglyceride, cholesterol and lactate concentrations were measured during 90 min treadmill exercise at a work intensity of 55–60% maximum.
• 2.2. After 90 min exercise plasma glucose fell by 35% whilst the non-esterified fatty acid concentration rose to as much as 3–4 times resting.
• 3.3. Exercise had no significant effect on plasma cholesterol, triglyceride or lactate concentrations.
• 4.4. The findings indicate a progressive increase in fat utilization during prolonged exercise. Possible hormonal mechanisms underlying exercise-induced changes in lipid and carbohydrate metabolism are discussed.

     

Proteomics Analysis of Extracellular Matrix Remodeling During Zebrafish Heart Regeneration

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Highlights

• •We have developed a decellularization protocol for ECM protein enrichment.
• •We have characterized the proteome of adult zebrafish heart ECM.
• •We describe dynamic changes in heart ECM proteome during regeneration.
• •We describe changes in heart ECM stiffness during regeneration.

     

Role of the visceral nerve in heart rate variations during different behavioral patterns in Megalobulimus sanctipauli (mollusca,gastropoda, pulmonata)

• 1.1. The role of the visceral nerve in mediating the changes in heart rate associated with different behavioral patterns was investigated in Megalobulimus sanctipauli.
• 2.2. The results of acute and chronic denervation experiments indicate that the visceral nerve has no excitatory or inhibitory tonic action on the heart of snails retracted into the shell, nor does it account for the increase in heart rate associated with the locomotion and feeding behaviors.
• 3.3. These changes in heart rate are, probably, indirect effects of increased activity such as an increase in venous return.
• 4.4. The visceral nerve is responsible for approximately 3/4 of the increase in heart rate associated with the first minute of extrusion.
• 5.5. The small increase in heart rate observed in denervated animals is probably caused by an increase in venous return generated by muscle activity that forces the head and food out of the shell.

     

Isolation and characterization of phospholipase A2, from Agkistrodon bilineatus (common cantil) venom

• 1.1. Phospholipase A₂ was isolated from Agkistrodon bilineatus venom by Sephadex G-75 and CM-Cellulose column chromatographies.
• 2.2. The purified phospholipase A₂-I gave a single band on disc polyacrylamide gel electrophoresis, isoelectric focusing and sodium dodecyl sulfate polyacrylamide gel electrophoresis.
• 3.3. The enzyme preparation had a molecular weight of 14,000, isoelectric point of pH 8.77 and possessed 123 amino acid residues.
• 4.4. The purified phospholipase A₂ possessed lethal, indirect hemolytic and anticoagulant activities.
• 5.5. The enzyme hydrolyzed the phospholipids phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl inositol (PI) and phosphatidyl serine (PS).
• 6.6. The concentration of mouse diaphragm was inhibited and the contraction of guinea pig left atrium was increased by phospholipase A₂-I.
• 7.7. Phospholipase A₂ activity of this preparation was inhibited by ethylenediamine tetraacetic acid, p-bromo phenacyl bromide, n-bromo succinimide or dithiothreitol, but not by diisopropyl fluorophosphate or benzamidine.

     

Phospholipids composition and metabolism in the hemolymph of Carcinus maenas (Crustacea,Decapoda)—Effect of temperature

• 1.1. The distribution of different phospholipids and the repartition of fatty acids extracted from hemolymph of crab Carcinus maenas are analysed.
• 2.2. The action of the temperature on the lipid composition is also determined: an increase of content of PE and a slight rise of the degree of unsaturation of fatty acids are found at lower temperatures.
• 3.3. The specific radioactivity of total phospholipids, phosphatidyl-choline and phosphatidylethanolamine from hemolymph of Carcinus maenas is studied from two radioactive precursors (³²Phosphorus and ³H]ethanolamine). Results suggested that the conversion of PE into PC by methylation could take place in hepatopancreas of Carcinus maenas.
• 4.4. The specific radioactivity of phospholipids from these two same radioactive compounds is increased following a variation in the environmental temperature.
• 5.5. The composition of hemolymph lipids could be a direct reflection of the lipid metabolism of the hepatopancreas and that the temperature alters the rate of the phospholipid exchange between hepatopancreas and hemolymph.
• 6.6. It is suggested that these lipid alterations occur in order to permit crab Carcinus maenas to support large changes in environmental temperatures.

     

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.

     

Effect of ozone exposure on the compositions of gill and erythrocyte membrane lipids and proteins of Japanese charr (Salvelinus leucomaenis)

• 1.1. Compositions of lipids and proteins of erythrocytes (RBC) and gills from Japanese charr (Salvelinus leucomaenis) which were exposed to 0.4 and 0.7 ppm ozone for 30 min were compared with those of the control.
• 2.2. On exposure to ozone, both RBC and gill membrane phospholipid content, especially phosphatidylethanolamine (PE), dropped.
• 3.3. The decrease of PE was brought about by the decrease of docosahexaenoic acid content which comprised the major component of PE.
• 4.4. RBC membrane protein with 215 and 225 kDa, which is equivalent to cytoskeletal protein, selectively disappeared on exposure to ozone.

     

Human sciatic nerve phospholipid profiles from non-diabetes mellitus,non-insulin-dependent diabetes mellitus and insulin-dependent diabetes mellitus individuals. A 31P NMR spectroscopy study

• 1.1. Human sciatic nerve phospholipids obtained from non-diabetes mellitus (NDM), non-insulin-dependent diabetes mellitus (NIDDM), and insulin-dependent diabetes mellitus (IDDM) patients, after lower extremity amputation, were studied by ³¹P NMR spectrometry.
• 2.2. Nine phospholipids resonances in NDM and NIDDM groups were identified as followed: Ethanolamine plasmalogen (Epias, Chemical shift = 0.07δ); phosphatidylethanolamine (PE, 0.03δ); phosphatidylserine (PS, −0.05δ); sphingomyelin (SM, −0.09δ); lysophosphatidylcholine (LPC, −0.28δ); phosphatidylinositol (PI, −0.30δ); alkylacylphosphorylcholine (A1.PC, -0.78δ); phosphatidylcholine (PC −0.84δ), and an unknown resonance (U, 0.13δ).
• 3.3. In the IDDM group a resonance of lysophosphatidylinositol (LPI, 0.01δ) was detected in addition to the nine phospholipids listed above.
• 4.4. IDDM showed that PI and Al.PC were elevated and U was lower when compared with NDM; also, Eplas was lower when compared with NIDDM. PC was elevated and PS was lower when compared with both NDM and NIDDM.
• 5.5. Indices calculated from this data, showed that the choline ratio and choline/ ethanolamine ratio were elevated; while ethanolamine ratio, and myelin ratio were lower in IDDM group, when compared with both NDM and NIDDM groups.
• 6.6. Inactivation of the cholineacethyltransferase enzyme (ChAT) and enhancement of the phospholipidmethyltransferase enzyme (PLMT), secondary to an insulin deficiency, are proposed as an interpretation of these findings.

     

Effects of phosphatidylserine on the oxidation of low density lipoprotein

• 1.1. LDL was incubated in the presence of 1 μ M CuSO₄ for 18 hr at 37°C. The content of lipoperoxides was found to be approx. 40 nmol MDA equivalents/mg LDL protein. The addition of 50 μM phosphatidylserine (PS) reduced the content of lipoperoxides to 15% of control values.
• 2.2. The electrophoretic mobility observed for LDL oxidized in the presence of PS approximated the mobility observed for native LDL.
• 3.3. The formation of conjugated dienes was strongly inhibited when LDL was oxidized in the presence of PS.
• 4.4. The addition of 50 μM phosphatidylcholine, phosphatidylglycerol and cardiolipin did not alter the extent of LDL oxidation.
• 5.5. PS did not inhibit the oxidation of LDL mediated by J774 macrophages in the presence of Ham's F-10 culture medium. Under these conditions, PS was found to be an excellent substrate for oxidation.

     

The effect of hypoxia on carbohydrate metabolism in flounder (Platichthys flesus L.)—I. Utilization of glycogen and accumulation of glycolytic end products in various tissues

• 1.1. Resting oxygen consumption at 10°C did not change from normoxia (150 mm Hg) down to an oxygen tension of 55 mm Hg for the flounder, Platichtys flesus.
• 2.2. Flounders exposed to hypoxia showed increased levels of blood glucose and lactate, dependent on the degree of hypoxia.
• 3.3. Due to hypoxia glycogen was depleted in the liver and swimming muscle but in the heart there was no significant change.
• 4.4. Liver glucose increased after 7 hr of hypoxia. Heart and muscle glucose did not change but the absolute glucose concentration in the heart was five times higher than in the muscle.
• 5.5. There is a transient accumulation of lactate in heart, liver and kidney after 7 hr of hypoxia while lactate accumulation in the swimming muscle is significant only after 21 hr of hypoxia.
• 6.6. Succinate only accumulated in the liver while alanine accumulated in muscle, heart and liver.

     

The effects of osmotic stressors on the stenohaline carp (Cyprinus carpio)

• 1.1. Carp were acclimatized to different concentration of urea and mannitol.
• 2.2. The fish survived in 300 mOsm urea and 262 mOsm mannitol for a longer period. Higher concentrations were only tolerated for a short time.
• 3.3. Urea penetrated into the animals. The internal concentration of urea in plasma was nearly equal to the outside concentration after 7 days. Therefore a very high internal osmolality was adjusted (sum of normal and urea osmolality).
• 4.4. Urea treatment only resulted in changes of Ca level, while the concentration of other electrolytes was not clearly varied.
• 5.5. Extracellular space of muscle was reduced while the intracellular space remained unchanged after urea treatment.
• 6.6. Mannitol treatment resulted in changes of electrolyte concentrations due to dehydration.
• 7.7. After 1 day of treatment the concentration of Na in plasma decreased which might indicate the limitation of tolerance.
• 8.8. Immediate shrinkage of ICS and, later, reduction of ECS were clear reactions to mannitol influence.

     

Correlation of water translocation,cuticle dehydration and post-ecdysial sclerotization by the american cockroach

• 1.1. Haemolymph volume decreases during the initial 16 hr post-ecdysial period, increases after water ingestion and subsequently drops until the inter-ecdysial level is reached.
• 2.2. Total body water follows a similar pattern, but the changes are not as pronounced.
• 3.3. Tissue water is inversely proportional to the total body water.
• 4.4. Soluble cuticle protein declines throughout the initial 16 hr period while both β-glucosidase and alkaline phosphatase activity is lost within 6 hr after ecdysis.
• 5.5. Dehydration of the cuticle also occurs during the immediate 6 hr post-ecdysial period.
• 6.6. These data suggest that the formation of the protein-insoluble matrix is linked with water loss.
• 7.7. Water removal may decrease the distance between molecules allowing specific reactions to take place.

     

Acid hydrolase activity in tissues of mice after physical stress

• 1.1. The activities of β-glucuronidase and cathepsin D and the protein concentration were assayed from brain, kidney, liver, cardiac muscle and skeletal muscle (m. rectus femoris) samples from mice (Mus musculus) 1, 3, and 6 days after intermittent exhaustive (duration 100–145min) and submaximal prolonged (duration 9 hr) running on treadmill.
• 2.2. The activity of β-glucuronidase in skeletal muscle strongly increased being the highest 3 days after both exertions. Cathepsin D activity also slightly increased. In cardiac muscle β-glucuronidase activity was unaffected. Cathepsin D activity slightly increased 3 days after intermittent exhaustive exercise.
• 3.3. The specific activities of β-glucuronidase and cathepsin D in the liver increased 1 day after the both exertions. Simultaneously the protein concentration decreased. In the kidney β-glucuronidase activity and protein concentration were unaffected but cathepsin D activity decreased 1 day after intermittent exhaustive exercise.
• 4.4. In the brain protein concentration transiently decreased 3 days after the exertions. β-Glucuronidase activity transiently decreased 1 day after intermittent exercise thereafter increasing 6 days afterwards above the control level. Cathepsin D activity decreased 1 day after intermittent exercise but was unaffected after prolonged submaximal exercise.
• 5.5. Physical stress affected to varying extent the acid hydrolase activities in all organs studied.