山蝠和黑斑蛙乳酸脱氨酶同工酶及血糖浓度的季节变化

本工作采用聚丙烯酸胺凝胶电泳等方法,对山蝠（Ｎｙｃｔｕｓｎｏｃｔｕｌａ）和黑斑蛙（Ｒａｎａｎｉｇｒｏｍａｃｕｌａｔａ）在冬眠或蛰伏期与活动期的血清、脑、骨胳肌中的乳酸脱氢酶（ｌａｃｔａｔｅｄｅｈｙｄｒｏｇｅｎａｓｅ,ＬＤＨ）同工酶和血糖浓度进行了比较研究。ＬＤＨ同工酶及血糖浓度表现出明显的季节变化。与活动期的动物相比,在冬眠或蛰伏期中的动物的ＬＤＨ１缺乏、ＬＤＨ５明显增多（Ｐ＜０．００１）,血糖浓度明显升高（Ｐ＜０．００１）。此外,ＬＤＨ同工酶和血糖浓度的季节变化在冬眠动物和蛰伏动物之间还存在着明显的差异。这些结果提示,ＬＤＨ同工酶含量和血糖浓度的季节变化不仅与动物的能量代谢水平相适应,而且显示了冬眠和蛰伏两种生理过程中的可能差异。     

Level of dehydrogenase activity in chipmunks under normal conditions and during chronic external gamma-irradiation

Chipmunks were chronically exposed to gamma-radiation at an average dose rate of 46 pA/kg. Changes in activity of succinate dehydrogenase (EC 1.3.99.1), pyruvate dehydrogenase (EC 1.2, 4.1) and lactate dehydrogenase (EC 1.1.1.27) were detected in the homogenates of the cardiac muscle, liver and brain at different physiological periods (before, during and after hibernation). The changes observed were related to the impairment of coordination between the processes of tissue respiration and glycolysis.     

Lactate Dehydrogenase Isozymes in the Tissues of Hibernating Bats (Chiroptera)

A comparative electrophoretic assay of lactate dehydrogenase (EC 1.1.1.27) isozymes has been carried out in the homogenates of the tissues of cardiac and skeletal muscles, liver, kidneys and lungs of five species of hibernating bats of the order Chiroptera: the northern bat Eptesicus nilssonii Keyserling and Blasius, the brown long-eared bat Plecotus auritus L., Brandt’s bat Myotis brandtii Eversmann, Daubenton’s bat Myotis daubentonii Kuhl, and the whiskered bat Myotis mystacinus Kuhl, which live in Karelia near the northern border of their distribution area. High contents of aerobic lactate dehydrogenase 1 and lactate dehydrogenase 2 isozymes have been detected in the skeletal muscle of the studied bats. The lactate dehydrogenase isozyme spectra of the tissues of kidneys and skeletal muscles from the smaller representatives of bats (the whiskered and Brandt’s bats) contained the highest content of H subunits among the studied species. In contrast, the predominance of M subunits has been revealed in the lactate dehydrogenase isozyme spectra of the kidneys of the northern and the brown long-eared bats. The discovered interspecies differences are discussed in the context of the adaptation of bats to hibernation.     

Aerobic capacity of frog skeletal muscle during hibernation

Frogs submerged at 3 degrees C in hypoxic water (Po2=60 mmHg) depress their metabolic rate to 25% of that seen in control animals with access to air. The hypometabolic state of the skeletal muscle in such cold-submerged frogs is thought to be the most important contributor to the overall metabolic depression. The aim of this study was to determine whether the aerobic capacity of frog skeletal muscle became altered during 1-4 mo of hibernation to match the reduction in adenosine triphosphate (ATP) demand. To this end, the activities of key mitochondrial enzymes were measured in the skeletal muscle and in isolated mitochondria of frogs at different stages during hibernation. We also measured the activity of lactate dehydrogenase (LDH) as an indicator of glycolytic capacity. The activities of cytochrome c oxidase, citrate synthase, and LDH were significantly lower in frog skeletal muscle after 4 mo of hibernation compared with control conditions. The reduction in skeletal muscle aerobic capacity is apparently due to changes in the intrinsic properties of the mitochondria. Overall, these results indicate an important reorganisation of ATP-producing pathways during long-term metabolic depression to match the lowered ATP demand.     

The effect of exercise and restraint on pectoral muscle metabolism in pigeons

The effect of various activity regimes on metabolism of pigeon pectoralis was examined by measurement of blood lactate following exercise, total lactate dehydrogenase activity of pectoral muscle, and proportions of specific isoenzymes of pectoral muscle lactate dehydrogenase. Sprint-trained birds had the highest pectoral muscle lactate dehydrogenase activity (1409 IU · g⁻¹ wet tissue), while endurance-trained birds had the highest peak lactate levels (287 mg · dl⁻¹, extrapolated from decay curves) and fastest half-time of the lactate response (4.8 min) following exercise, but the lowest lactate dehydrogenase activity (115 IU · g⁻¹ wet tissue). Immobilization of one wing for 3 weeks following endurance training produced a marked increase in lactate dehydrogenase activity of the immobilized muscle, compared to that in the contralateral pectoralis and endurance-trained muscle. Aerobic forms of the lactate dehydrogenase enzyme (that favor conversion of lactate to pyruvate) predominated in pectoral muscle of endurance-trained birds, while cage-confined birds exhibited primarily the anaerobic isoenzymes. These results demonstrate that conversion of pectoral muscle lactate dehydrogenase isoenzymes, total lactate dehydrogenase activity, and half-time of lactate response after exercise is dependent on activity regime in pigeons. In this respect, pigeon pectoral muscle responds to training and disuse in a manner similar to that of mammalian skeletal muscle. Accepted: 10 September 1996     

Changes in the activity of selected enzymes during starvation of Physarum polycephalum

The levels of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, lactate dehydrogenase, and cyclic phosphodiesterase activities were examined in growing and starving plasmodia of Physarum polycephalum. The activities of lactate dehydrogenase, 6-phosphogluconate dehydrogenase, and glucose-6-phosphate dehydrogenase decreased whereas that of cyclic phosphodiesterase increased. The change in activity of lactate dehydrogenase was the result of the variation of the activity of a single enzyme quite similar to the lactate dehydrogenases of higher animals.     

Lactate Dehydrogenase in Oryza sativa L. Seedlings and Roots: Identification and Partial Characterization

A lactate dehydrogenase activity is present in rice (Oryza sativa L.) seedlings and roots. Under aerobic conditions, lactate dehydrogenase activity is barely detectable in rice seedlings and is very low in rice roots. In 30 day old roots, the activity is increased two to three times by an anoxic or hypoxic treatment and can be detected on immunoblots by an antiserum raised against barley lactate dehydrogenase. The activity present in aerobic seedlings was partially purified. The native enzyme has a molecular mass of 160 kilodaltons, and is a tetramer of 2 subunit (38 and 39 kilodaltons) randomly associated. Studies of substrate specificity, native gel electrophoresis, and immunoblot analysis indicate that the partially purified enzyme is a typical lactate dehydrogenase. However, no increase of lactate dehydrogenase activity or protein was observed in seedlings transferred to anoxia.     

Evidences of Basal Lactate Production in the Main White Adipose Tissue Sites of Rats. Effects of Sex and a Cafeteria Diet

Female and male adult Wistar rats were fed standard chow or a simplified cafeteria diet for one month. Then, the rats were killed and the white adipose tissue (WAT) in four sites: perigonadal, retroperitoneal, mesenteric and subcutaneous (inguinal) were sampled and frozen. The complete WAT weight in each site was measured. Gene expression analysis of key lipid and glucose metabolism enzymes were analyzed, as well as tissue and plasma lactate and the activity of lactate dehydrogenase. Lactate gradients between WAT and plasma were estimated. The influence of sex and diet (and indirectly WAT mass) on lactate levels and their relationships with lactate dehydrogenase activity and gene expressions were also measured. A main conclusion is the high production of lactate by WAT, practically irrespective of site, diet or sex. Lactate production is a direct correlate of lactate dehydrogenase activity in the tissue. Furthermore, lactate dehydrogenase activity is again directly correlated with the expression of the genes Ldha and Ldhb for this enzyme. In sum, the ability to produce lactate by WAT is not directly dependent of WAT metabolic state. We postulate that, in WAT, a main function of the lactate dehydrogenase path may be that of converting excess available glucose to 3C fragments, as a way to limit tissue self-utilization as substrate, to help control glycaemia and/or providing short chain substrates for use as energy source elsewhere. More information must be gathered before a conclusive role of WAT in the control of glycaemia, and the full existence of a renewed glucose-lactate-fatty acid cycle is definitely established.     

Seasonal biochemical plasticity of a flight muscle in a bat, Murina leucogaster

Cellular and biochemical responses of the pectoral muscle to variation in seasonal activity were studied in the bat, Murina leucogaster ognevi. We collected bats in mid-hibernation (February), end-hibernation (April), and mid-summer (August) to track major activity periods in their annual cycle. Our findings indicated that myofiber cross-sectional area decreased to 68% between mid- and end-hibernation, but returned to the winter level in mid-summer. Total soluble protein and total RNA concentrations were not altered over these sampling periods. Oxidative potential gauged by citrate synthase activity increased 1.47-fold from mid- to end-hibernation and then remained at the similar level in mid-summer. Glycolytic potential gauged by lactate dehydrogenase activity changed little between mid- and end-hibernation but increased 1.42-fold in summer, compared with the winter level. Thus, the myofibers underwent disuse atrophy during hibernation, while enzymatic catalytic function recovered towards the level of mid-summer.     

Ultrathin-layer microelectrophoretic determination of lactate dehydrogenase isoenzymes in corneal and conjunctival epithelium of the cow

In order to evaluate the impact of tissue oxygenation on the distribution pattern of lactate dehydrogenase isoenzymes, activities of the isoenzymes were measured in microdissected samples of bovine tissue. A highly sensitive ultrathin-layer electrophoretic technique was used to determine the distribution pattern of lactate dehydrogenase isoenzymes in basal, intermediate and superficial layers of the epithelium of central and peripheral cornea and in the epithelium of the bulbar conjunctiva. Measurements revealed almost homogeneous intraepithelial distribution patterns of lactate dehydrogenase isoenzymes in both tissues. In the cornea the lactate dehydrogenase isoenzymes 4 and 5, which are regarded to be specialized for anaerobic glucose metabolism, were found to predominate. In the well-oxygenated conjunctival epithelium most of the activity could be ascribed to the lactate dehydrogenase isoenzyme 3. In contrast to the isoenzymatic activities, total activity of lactate dehydrogenase was inhomogeneously distributed; maximum activities were found in the basal layer of corneal epithelium and in the intermediate layer of conjunctival epithelium. The results indicate that oxygen supply is relevant rather for the intraepithelial distribution of total enzyme activity than for the expression of lactate dehydrogenase isoenzymes.Parts of this study were presented as an inaugural dissertation to the Medical Faculty of the University of Basel by K. Krieger     

Correlations between components of the glycolytic pathway

1. The contents of dihydroxyacetone phosphate, fructose diphosphate, pyruvate and lactate and the activities of aldolase and lactate dehydrogenase in the liver, kidney, testis, skeletal muscle, blood cells, sarcoma and hepatoma of rats were measured. 2. Correlations were established between components of the glycolytic pathway as follows: activities of aldolase and lactate dehydrogenase; contents of fructose diphosphate and pyruvate; activity of aldolase and content of fructose diphosphate; activity of lactate dehydrogenase and contents of fructose diphosphate and of pyruvate.     

The effect of cell-phone radiation on rabbits: Lymphocyte enzyme-activity data

The effect of a GSM 900/1800 mobile phone, which is a widespread source of electromagnetic radiation of the microwave frequency in the environment, on rabbits was studied at power densities of 5–7 μW/cm². The biological effect was recorded by a sensitive method for the detection of the physiological regulation of enzyme activity inside lymphocytes in blood smears. Succinate dehydrogenase, which is the most powerful energy-supply enzyme in mitochondria, and lactate dehydrogenase, which is an enzyme of glycolysis, were measured. The lactate dehydrogenase to succinate dehydrogenase activity ratio was also calculated as an analog of the Warburg effect, which demonstrates the relationship between glycolysis and respiration. After 60 min of mobile-phone exposure each day for 11 days at a moderate dose, the emitted radiation induced a threefold increase in succinate dehydrogenase activity and a twofold decrease in lactate dehydrogenase activity. As a result, the lactate dehydrogenase/succinate dehydrogenase activity ratio falls from 15 to 5, thus indicating that respiration is predominant over glycolysis. The changes develop already after the first exposure and reach a maximum in 4 days. The predominance of respiration is usually considered as a beneficial state of an organism. However, continuous activation of respiration by mobile phone exposure may cause damage to the normal restorative processes that are supported by glycolysis during periods of rest.     

A quantitative histochemical study of lactate dehydrogenase and succinate dehydrogenase activities in the membrana granulosa of the ovulatory follicle of the rat

Using a microdensitometer, lactate dehydrogenase and succinate dehydrogenase activities were measured in the membrana granulosa of the rat ovulatory follicle. Ovaries were removed on each day of the oestrous cycle; oestrus, dioestrus-1, dioestrus-2, and proestrus; and enzyme activities measured in the membrana granulosa as a whole and in four regions within it: peripheral (PR), antral (AR), cumulus oophorus (CO) and corona radiata (CR). Throughout the cycle, lactate dehydrogenase activity was greatest in PR. On oestrus, lactate dehydrogenase activity was progressively less in AR, CO and CR. On dioestrus-1, activity was identical in AR and CO and less in CR. On dioestrus-2, activity was greater in AR than in CO or CR. By proestrus, activity was equal in AR, CO and CR. In the membrana granulosa as a whole, and in each region, lactate dehydrogenase activity declined as ovulation approached. In contrast, succinate dehydrogenase activity in the membrana granulosa as a whole and in PR was constant throughout the cycle. Activity fluctuated in the other regions. Succinate dehydrogenase activity on oestrus was greatest in PR, less in AR and CO and least in CR. On the remaining days, succinate dehydrogenase activity was greatest in PR and less but equal in the remainder of the membrana granulosa.     

Alteration of lipid composition,Na+, K+-ATPase and Δ5-β-hydroxy steroid dehydrogenase activities in microsomal membranes of mature toad ovary in different seasons

Microsomal membranes isolated by sucrose density gradient centrifugation from mature toad ovary has been found to vary significantly in lipid composition and various enzyme activities in different seasons. Na⁺, K⁺—ATPase activity is the highest in breeding season (rainy season). Significantly the optimum temperature for enzyme activity is 30°C. The other enzyme Δ⁵-3β-hydroxysteroid dehydrogenase activity is also lower in hibernation period than other seasons. The total phospholipid, sterol and fatty acid contents differ significantly between seasons. The poly-unsaturated fatty acid, except arachidonic acid content in hibernation period is much lower than that during other seasons. The sterol content is also the lowest in this season. The present findings indicate that during hibernation period the membrane is more rigid and the metabolic activity of the animal is slow because of a lower level of various functionally important enzyme activities. Part of this work was presented at the 13th International Union of Biochefstry Congress, held at Amsterdam in August 1985.     

Lactate dehydrogenase activity in the mitochondrial fraction of chicken liver: enzyme binding and kinetic behavior of soluble and bound enzyme

Chicken liver crude mitochondrial fraction showed lactate dehydrogenase activity (6.5% of cytoplasmic enzyme). Most of the mitochondrial lactate dehydrogenase was solubilized by sonication of the mitochondrial fraction in 0.15 M NaCl, pH 6. Total extracted lactate deshydrogenase activity was 3-fold higher than the initial pellet activity. Different isoenzymatic compositions were observed for cytosoluble and mitochondrial extracted lactate dehydrogenase. The pI, values of the 5 lactate dehydrogenase isoenzymes were found to be independent of their origin. The cytosoluble lactate dehydrogenase and the separated H4,H3M and H2M2 isoenzymes were able to bind to the chicken liver mitochondrial fraction in 5 mM sodium phosphate buffered medium, and could be solubilized afterwards with 0.15 M NaCl, pH 6. The enzyme bound to the mitochondrial fraction was less active than the soluble one. Particle saturation by the bound enzyme occurred with all mitochondrial fractions assayed. According to the Langmuir isotherm, the non-sonicated mitochondrial fractions contain a single type of binding sites for lactate dehydrogenase; in contrast, the sonicated mitochondrial fraction should contain different binding sites. Chicken liver crude or sonicated active mitochondrial fractions showed a hyperbolic behavior with respect to NADH and a non-hyperbolic one with respect to pyruvate. This mechanism is different from the bi-bi compulsory order mechanism of the soluble enzyme. With hydroxypyruvate as the substrate, the active mitochondrial fraction fit a sequential mechanism but lost the rapid-equilibrium characteristics of the soluble enzyme.     

Lactate dehydrogenase isozyme patterns in the denervated quail (Coturnix coturnix japonica) muscles

Polyacrylamide gel electrophoresis of the Japanese quail (Coturnix cotunix japonica) muscle extracts revealed a single lactate dehydrogenase isozyme. A month after surgical unilateral brachiotectomy (denervation) there was significant atrophy of the triceps, biceps and radius ulnar muscles accompanied by the appearance of an additional lactate dehydrogenase isozyme band. This extra band may be the result of the synthesis of a new lactate dehydrogenase isozyme. This new isozyme exhibited a lower affinity for lactate, less sensitivity to urea denaturation and was more thermostable than the lactate dehydrogenase of normal (innervated) quail muscles. Based on these properties, it is suggested that the newly synthesised isozyme of the denervated muscles is LDH-1, (or B4/H4) type. Brachiotectomy also resulted in significant quantitative changes in the total lactate dehydrogenase activity of innervated muscles of the same animal.     

Lactate dehydrogenase has no control on lactate production but has a strong negative control on formate production in Lactococcus lactis.

A series of mutant strains of Lactococcus lactis were constructed with lactate dehydrogenase (LDH) activities ranging from below 1% to 133% of the wild-type activity level. The mutants with 59% to 133% of lactate dehydrogenase activity had growth rates similar to the wild-type and showed a homolactic pattern of fermentation. Only after lactate dehydrogenase activity was reduced ninefold compared to the wild-type was the growth rate significantly affected, and the ldh mutants started to produce mixed-acid products (formate, acetate, and ethanol in addition to lactate). Flux control coefficients were determined and it was found that lactate dehydrogenase exerted virtually no control on the glycolytic flux at the wild-type enzyme level and also not on the flux catalyzed by the enzyme itself, i.e. on the lactate production. As expected, the flux towards the mixed-acid products was strongly enhanced in the strain deleted for lactate dehydrogenase. What is more surprising is that the enzyme had a strong negative control ( CLDHJF1 =-1.3) on the flux to formate at the wild-type level of lactate dehydrogenase. Furthermore, we showed that L. lactis has limited excess of capacity of lactate dehydrogenase, only 70% more than needed to catalyze the lactate flux in the wild-type cells.     

The effect of thiamine and its metabolites on the activity of tissue and purified lactate dehydrogenase

It is shown that thiamine and its metabolites effect lactate dehydrogenase activity and lactate content in the tissues. Thiochrome and thiamine phosphate increase the lactate level in the liver and small intestine. The given effect correlates with the inhibition of the tissue and purified lactate dehydrogenase by thiochrome.     

Effect of boseimycin on some enzyme systems ofBacillus subtilis

The effect of boseimycin on the in vitro activity and in vivo synthesis of alkaline phosphatase, aconitase and lactate, isocitrate, glutamate and alanine dehydrogenases was studied in Bacillus subtilis. At a subinhibitory concentration, synthesis of glutamate dehydrogenase was stimulated but alkaline phosphatase, lactate dehydrogenase and aconitase synthesis was inhibited. On the contrary, boseimycin inhibited slightly the activity of lactate dehydrogenase in cell-free extracts. Glutamate dehydrogenase and aconitase activities were not affected.     

Frog hepatocyte modifications induced by seasonal variations: a morphological and cytochemical study.

A correlated morphological and cytochemical approach was employed to study frog hepatocytes in different periods of their annual cycle, including the natural hibernating period. There were considerable changes in the distribution and organization of hepatic glycogen in different phases of the annual cycle, and distribution of organelles as well. The most striking findings were glycogen storage during the prehibernation and hibernation phases, followed by drastic glycogen depletion. Cytochemical staining of a number of enzymes (succinate dehydrogenase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, paranitrophenyl phosphatase, acid phosphatase, and glucose-6-phosphatase) involved in a variety of metabolic pathways, showed various cytoplasmic localizations and differences in intensity of the reaction products as a function of seasonality. Morphological and cytochemical data were interpreted as evidencing different functional requirements during seasonal changes in the frog.