Lactate dehydrogenase isoenzymes. Turnover in rat heart, skeletal muscle, and liver

Pj, Fritz; El, White; Km, Pruitt; Es, Vesell

doi:10.1021/bi00745a003

Cited by 39 publications

(6 citation statements)

References 19 publications

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“…Section VII/s Fritz, White, Pruitt & Vesell (1973) have extended their observations on lactic dehydrogenase. From experiments involving the continuous administration of radioactive amino acid, they found that forms of this sarcoplasmic enzyme that accumulate most in cardiac and skeletal muscle are degraded comparatively slowly.…”

Section: Section Vii/4mentioning

confidence: 90%

On the Cellular Regulation of Growth and Development in Skeletal Muscle

Burleigh

1974

Biological Reviews

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Summary 1. Fibres of skeletal muscle in different mammalian species vary more in number and in their rates of growth than in their ultimate breadth, and they grow more slowly in cattle and man than in rats and mice. Cells of large mammalian species probably divide comparatively slowly in pre‐natal life but do so for longer, and thus they attain greater numbers than do their counterparts in smaller mammals. Such cells include the precursors of muscle, and common mechanisms may therefore limit rates of growth before and after muscles form. If some metabolic processes are slower in mammals destined to be large, corresponding trends in age‐related cellular changes which ultimately suppress mitotic activity may cause differences between species in the overall size of muscles and in that of other tissues. This is probably an oversimplification. 2. It is difficult to decide how far the rate of growth and the final diameters of muscle fibres reflect the number of myoblasts which initially fuse into myotubes and the number of myoblasts which are subsequently incorporated into individual fibres. New nuclei are probably added with age along the length of a fibre, but it is uncertain whether they then synthesize ribosomes which produce contractile protein. It seems likely that fibres elongate to different extents by adding myoblasts terminally. 3. There is some evidence that myofibrils grow throughout the depth of a fibre by adding new myofilaments to their surface, but there is none that is convincing to the effect that myofibrils form de novo at a fibre's periphery. Ribosome‐like structures distributed in the sarcoplasm between myofibrils have been described, and their numbers decline in comparison with those of the myofibrils during growth. Thus, fibres possibly attain their maximum breadth when the loss of superficial filaments from myofibrils exceeds the capacity of ribosomes to replace them. The evidence is inconclusive as to whether myofitrillar protein is broken down and replaced at rates which vary within a muscle or between muscles differing in physiological properties. Sarcoplasmic proteins appear to be replaced more rapidly than those in myofibrils. It is also speculated that muscle proteins are synthesized and degraded more slowly in species which take longer to develop. 4. Observations, with the microscope suggest that new ribosomes appear in cells which are becoming myoblasts. Whether the ribosomes subsequently break down is not established. The evidence that I‐somes occur in muscle is inconclusive, as is that for the existence of messenger RNA and its selective synthesis when muscle is forming in the embryo. 5. A decline in the synthesis of RNA occurs as myotubes appear and contractile protein begins to accumulate. The significance of this phenomenon is not known, and in more mature muscle some RNA also appears to fluctuate in a fashion which is unrelated to rates of controlling protein synthesis. Such RNA may occur at the periphery of fibres or in satellite cells. In some instances it may be formed by cells ...

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Section: Section Vii/4mentioning

confidence: 90%

On the Cellular Regulation of Growth and Development in Skeletal Muscle

Burleigh

1974

Biological Reviews

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“…It has been suggested that both constants are different for each isozyme and that the binomial distribution of the LDH isozymes is the result of a continuous in vivo assembly and disassembly of the LDH tetramers combined with a selective degradation of some of them (6)(7)(8). The intra-cellular occurrence of dissociation and reassociation of LDH tetramers has never been adequately tested.…”

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confidence: 99%

Evidence for the lack of feedback regulation of gene activity and for the absence of subunit exchange between lactate dehydrogenase tetramers in vivo.

Nadal‐Ginard¹

1976

Proc. Natl. Acad. Sci. U.S.A.

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Frog and rat lactate dehydrogenase (LDH, Llactate:NAD+ oxidoreductase, EC 1.1.1.27) isozymes, highly purified by affinity chromatography, were injected into newly fertilized frog (Rana pipiens) eggs to study the effect of the injected isozymes on the expression of the LDH genes of the de-veloping frog embryo. From these experiments three conclusions can be drawn: (i) homologous and heterologous LDH, even when present in more than twice the normal amount of LDH, does not play any role in-the switching on or off of the frog LDH genes or in regulating the level of gene activity. The intracellular levels of each LDH isozyme are dependent on both the rate constant for synthesis and the rate constant for degradation. It has been suggested that both constants are different for each isozyme and that the binomial distribution of the LDH isozymes is the result of a continuous in vivo assembly and disassembly of the LDH tetramers combined with a selective degradation of some of them (6-8). The intra-cellular occurrence of dissociation and reassociation of LDH tetramers has never been adequately tested.In the present investigation, these aspects of LDH regulation have been investigated by injecting homologous and heterologous LDH into newly fertilized Rana pipiens eggs. Three specific questions were examined: (a) Does MATERIAL AND METHODS Electrophoretic Separation. LDH isozyme separation was performed on starch gels, prepared as described by Boyer et al. (9). Resolution was achieved in 18 hr at 450 V. After electrophoresis was completed the gels were stained for LDH activity, as described by Markert and Faulhabr (10).Purification of LDH and Separation of the Isozymes. The LDH isozymes were purified from mouse and rat tissues by affinity chromatography with oxamate-aminohexyl-Sepharose-4B. LDH is bound to the immobilized analogue of pyruvate in the presence of NADH, and it is eluted when NADH is removed. This procedure gives a one step purification to homogeneity of all LDH isozymes studied (B. Nadal-Ginard, in preparation). The B4 isozymes were purified using a combination of blue dextran-Sepharose-4B (11) and oxamateaminohexyl-Sepharose-4B. LDH A4 was separated from the other isozymes on a DEAE-Sephadex A-50 column (12). After purification the LDH-isozymes were lyophilized and stored until used. LDH activity was measured as previously described (11).Rana pipiens Eggs. Mature eggs were obtained from gravid Rana pipiens females and fertilized according to procedures outlined in Rugh (13) as modified by Wright and Flathers (14). The eggs were "stripped" from the female into 100 mm Falcon petri dishes to form a circle around the edge of the dish and then covered with 10% Ringers solution. The jelly coat adheres strongly to the dish and immobilizes the egg during the injection procedure.Construction of Injection Pipettes. Coagulation glass capillary tubes (Fisher) were put on a vertical pipette puller (David Kopf Instruments) and the amount of heat in the coil regulated to produce a narrow bore section at least 8 mm...

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“…In our continuing studies on factors involved in the regulation of protein synthesis and degradation during differentiation and development (9,10,23), we have now measured the level of total tRNA in male and female rat liver, heart, skeletal muscle, and kidney at different times during postnatal developAided by grant CA 12808 from the US Public Health Service. ment.…”

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confidence: 99%

Transfer RNA and Aminoacyl Transfer RNA in Developing Rats

1976

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The total transfer RNA (tRNA) level in the liver, kidney, skeletal muscle and heart muscle of developing rats was determined by purification using (³H)tRNA as an internal standard. Liver and kidney contained almost twice as much tRNA per gram tissue as heart and skeletal muscle. There were no apparent differences between the sexes. The aminoacylation capacities of six tRNA species (alanyl, aspartyl, leucyl, methionyl, phenylalanyl, and tryptophanyl) from rat liver were not different during three developmental stages (suckling, weanling and young adult), and there were also no differences noted between males and females. The in vivo percent aminoacylation of four tRNAs (aspartyl, leucyl, methionyl, and phenylalanyl) was lower during the newborn and suckling periods than in weanling and young adult rat livers. The tRNA of young adults was almost completely aminoacylated in vivo with the exception of alanyl-tRNA.

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Lactate dehydrogenase isoenzymes. Turnover in rat heart, skeletal muscle, and liver

Cited by 39 publications

References 19 publications

On the Cellular Regulation of Growth and Development in Skeletal Muscle

On the Cellular Regulation of Growth and Development in Skeletal Muscle

Evidence for the lack of feedback regulation of gene activity and for the absence of subunit exchange between lactate dehydrogenase tetramers in vivo.

Transfer RNA and Aminoacyl Transfer RNA in Developing Rats

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