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(CANCER RESEARCH 34, 872-877, April 1974] Lactate and Pyruvate Metabolism and Reducing Equivalent Transfer in Ehrlich Ascites Tumor' Joseph Katz, Karl Brand,2 Sybil Golden, and David Rubinstein Cedars-Sinai Medical Research Institute, Los A ngeles, California 90029 SUMMARY teristics (9, 10). These strains reportedly differ greatly in GPDH3 activity (5, 9—1 1, 17, 18). It appeared to us that a The metabolism of labeled lactate and pyruvate by three strains of Ehrlich ascites tumor cells, H, HL, and W, was studied. The major products from the acids were CO2, amino acids (mainly alanine), and acetate. HL-cells are characterized by a high'4C yield in amino acids, and W-cells are characterized by their large acetate production. The rate of lactate and pyruvate oxidation was equal in Hand HL-cells, but W-cells oxidized pyruvate faster than lactate. Phenazine methosulfate stimulated lactate oxida tion in W-cells but not in the other two strains. Aminooxy acetate (2 mM) depressed ‘4C yields in amino acids by 80 to 90%. It had no effect on lactate oxidation in H- and HL cells, but depressed it in the W-cells by about 40%. The results suggest that the oxidation of cytosolic reduced nicotinamide adenine dinucleotide is rate limiting in the oxidation of lactate by W-cells but not the H- and HL-cells. INTRODUCTION Ascites cells, in common with many tumors, have a fairly high endogenous rate of oxygen uptake, and they oxidize lactate and pyruvate at substantial rates (20). The metabo lism of lactate differs from that of pynuvate by the produc tion of cytosolic NADH, which must be neoxidized either in the cytosol or by hydrogen transfer to mitochondnia. Comparative studies with the 2 acids have been of value to study the role of reducing equivalent transport in several organs. Several schemes for the oxidation of cytosolic NADH have been proposed, the most prominent ones being the aspartate : oxaloacetate : malate cycle (3) and the a-glyc erophosphate shuttle (4), but the mechanism of reducing equivalent transfer between cytosol and mitochondnia is not yet established. In 1905, Ehnlich isolated a line of mouse ascites tumor cells that have been propagated ever since in many labora tories. The cells have differentiated into several strains, distinct in chromosomal, growth, and biochemical charac ‘Supported by USPHS 2 Present address: Institute Grants 5ROIAN for Physiological 1260405 and RR Chemistry, The W. Contrary to published reports, we found the GPDH levels in all 3 strains to be similar. Our results indicate that oxidation of cytoplasmic NADH is rate limiting in the W-cells but not in the other strains. We provide some evi dence that transamination plays some role in reducing equivalent transfer in the W strain, but in the other strains the role of transamination appears to be minor. MATERIALS AND METHODS Ascites Cells. Hyperdiploid H-cells and hypodiploid Lettrémutant HL-cells were obtained from Dr. T. Terra nova, Universita Catholica, Rome, Italy. A hypotetraploid strain, W, was obtained from the Institute of Experimental Pathology of the Bayer AG. Werke in Wupperthal-Elber feld, Germany. According to Dionisi et al. (5), the activity of GPDH in the H strain was 25 times that in the HL strain. According to Letnansky (9, 10) and Letnansky and KIc (I I), who studied it extensively, the W strain had virtually no GPDH activity. The cells were propagated by i.p. injection into mice and were harvested 7 to 10 days after inoculation. Incubation. The peritoneal fluid was centrifuged and the cells were washed 4 to 5 times in 20 volumes of Krebs Henseleit bicarbonate buffer (19). Packed cells, 0.2 to 0.4 ml, were incubated in 2 ml of this buffer, in an atmosphere of 95% 02-5% CO2 in 50-mi Erlenmeyer flasks, closed with rubber serum caps, with center wells containing a vial for CO2 collection. The incubation at 38°was terminated by injection through the rubber cap of 2.0 ml phenethyla mine : water (1 : 1 v/v) into the vial and 0.5 ml 30% HC14 into the medium. Shaking was continued for 1 hr for ‘4C02 collection. Fractionation. The methods were essentially those used with other tissues (8). The medium and cells were trans 05468. Univer sity Erlangen-Nurnberg, 8520 Erlangen, Egerlandstrasse 7, Germany. Received November 5, 1973; accepted January 3, 1974. 872 comparison of the metabolism of lactate and pyruvate in such strains would be of interest. We describe the effects of PMS and the transaminase inhibitor AOA on the me tabolism of these acids by 3 strains, namely, H, HL, and 3 The abbreviations used are: GPDH, a-glycerophosphate dehydrogen ase; PMS, phenazine methosulfate; AOA, aminooxyacetic acid. CANCER RESEARCH VOL. 34 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. Reducing ferred quantitatively into tared l0-ml graduated centrifuge tubes and made to volume, and the supernatant fluid was neutralized with potassium bicarbonate. The cell residue was washed and dried to obtain the dry weight of the cells. Aliquots of the neutralized extract were used for assay of lactate, pyruvate, and acetate; about one-half passed through tandem columns (I x 8 cm) of Amberlite CG 120 (100 to 200 mesh) in H@ form, followed by a 1- x 10- cm column of Dowex AG 1-8 (100 to 200 mesh), in the acetate form. The columns were eluted with water and a 25-ml fraction was collected. This fraction consists of neutral compounds. The columns were separated, and the cation column was eluted with 20 ml of 2 N NH4OH. The am monia extract contains the amino acids fraction. The anion column was eluted with 100 ml 0.25 N acetic acid, which eluted acetate and most of the /@-hydnoxybutyrate, followed with 50 ml 1 N formic acid to elute lactate, followed with 70 ml of 4 N formic acid to elute pyruvate. The 4 N for mate fraction contained some phosphate esters. Finally, the column was eluted with 25 ml of I N ammonium fonmate. This removes most of the phosphate esters and di- and tn carboxylic acids. The cell residue was dissolved with warm ing in 0. 1 N KOH and the extract was made to volume. The 14Cin this fraction represents the insoluble residue. Enzyme Assays. Washed cells were stored frozen. The cells were thawed, suspended in 10 volumes of buffer, and treated sonically at maximum efficiency (Branson sonifier) 4 times for 30 sec with intermittent cooling. The super natant was used for enzyme assay according to the methods of Shonk and Boxer (15) and of Bergmeyen (2). Isotopes. L-Lactate and pyruvate, uniformly labeled with ‘4C,were purchased from New England Nuclear (Boston, Mass.) or Amersham/Searle Corp. (Chicago, Ill.). The lactate was isotopically pure, but pynuvate con tamed variable amounts ofp-pyruvate. When available, the pyruvate was purchased in 5 jzCi vials, and all of it was used immediately upon opening, avoiding storage. Alter. natively, the labeled pyruvate was taken up in 0. 1 N HC1, divided into lots that were stored at —20°,and was used immediately upon thawing. Nearly all commercial batches of labeled pyruvate contained some p-pyruvate, which in creased upon storage. The labeled pynuvate was analyzed by column chromatography with every experiment, and the activity in the pyruvate fraction was determined. The utili zation of ‘4Cwas calculated from the activity of this frac tion. The p-pyruvate seems to be metabolically inert. Solu tions of unlabeled pyruvate were prepared freshly before use. Other Assays. Acetate was assayed according to the method of Shulman and Wood (16). We gratefully ac knowledge the gift of acetokinase and succinyl-CoA from Dr. Marvin Shulman of Western Reserve University. Other assays were transformed enzymatically according to the method of Bergmeyer (2). Pyruvate assays were performed promptly after neutralization of the extract. The assay of ‘4C fractions by liquid scintillation was as described else where (8). Results were expressed as @tmoles or @iatoms carbon per 100 mg, dry weight. One ml of packed H- and HL-cells Equivalents Transftr in Ascites Tumor corresponds to 100 to I 10 mg, and I ml of W-cells come sponds to 120 to 130 mg, dry weight. RESULTS Lactate and Pyruvate. In Table I, the metabolism of the 2 acids by the 3 strains, H, HL, and W, is compared. The HL-cells are characterized by their high ‘4Cincorporation into amino acids, but otherwise the pattern in HL- and H-cells is similar. Very little pyruvate accumulates in the W-cells. The point of greatest interest is that in H- and HL-cells the utilization of lactate is nearly equal to that of pyruvate, whereas in the W-cells incorporation of pynuvate into products was I .5 to 2 times that of lactate. Further information on the pathway of the pyruvate moiety in HL- and W-cells is provided by the use of spe cifically labeled acids (Table 2). Labeled formed, as expected, solely from carbon atoms amino acids from pyruvate in both strains equally labeled from all 3 carbons, indicating acetate was 2 and 3. The were nearly the predomi nant direct formation of the amino acids from pyruvate. Alanine was indeed the predominant labeled amino acid. However, with lactate in W-cells, the incorporation of the canboxyl carbon into amino acids was much less than that of C-2 and C-3, indicating that in this case the amino acids are derived mainly by transamination of keto acids formed in the Knebs cycle. The yield of amino acids in the W-cells is small and the pyruvate concentration is low, so that it is likely that the pyruvate formed from lactate is preferen tially oxidized. This conclusion is supported by the finding of higher ‘4C02 yields from C-3 over C-2 of the lactate. This would occur only if there is some outflow from the Knebs cycle. Of special interest is the formation of acetate. Its identity was confirmed by Ducleaux distillation (I). Acetate is rarely if ever the metabolic end product in mammalian tissues, but Hepp et al. (7) observed its formation in several types of tumor cells. The highest yield among the tumors studies was in the tetraploid Ehnlich strain. The W strain is also tetnaploid. Calculations indicate that in these cells the acetyl-CoA is predominantly hydrolyzed, and only a small fraction is oxidized in the Knebs cycle. The amount of ace tate, as determined by analysis, exceeded that calculated from the “Cyield, especially in the W-cells, probably due to acetate formation from endogenous lipid. Chart I illustrates the kinetics of lactate and pyruvate utilization by the HL- and W-cells. Amino acid production levels off at about 30 to 50 mm. It is likely that ‘4Cincor ponation into amino acids is by transamination between pyruvate and endogenous amino acids, and the reaction is an exchange, rather than net synthesis, of amino acids. In the HL-cells, acetate formation decreases with time, whereas in the W-cells acetate formation from pyruvate is much higher and linear until the substrate is nearly ex hausted. Effect of PMS. The more rapid utilization of pyruvate than of lactate by W-cells suggested that oxidation of cy tosolic NADH was rate limiting. If this is the case, the APRIL 1974 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. 873 Joseph Katz, Karl Brand, Sybil Golden, and David Rubinstein Table I Metabolism of lactate and pyruvate by 3 strains of Ehrlich ascites cells Thirty-five to 43 mg cells were incubated in 2 ml bicarbonate buffer for I hr with 10 lactateH or pyruvate, uniformly labeled with “C.mM WLactate HL Pyruvate LactatePyruvateUptake:' Lactate Pyruvate mg)Lactate analytical (pmoks/100 —18' +1.5 17 Pyruvate Net @ Substrate used Lactateorpyruvateformed 19 1.5 CO2 Acetate Amino acids Residue Others Total 25 9 15 6 I 56 Lactate or pyruvate formed Other products Isotope recovery 3.6 39 99 a Metabolism oflactate formation; +7.5 —23 —25 +2.5 18 32Uptake:21 26 7.0 6.0Recovery 31 II 13 4 1 60 14 44 104 +11 —35 24 —15 +0.5 15+5.5 isotopic (j@moles/100 mg) 24 36 3.0 10 of(jig/atoms 26 6 33 6 71 94% carbonll00 33 7 30 5 —37 16 0.535 mg) in 18 17 9 4 75 4842 added “C 5.3 18 42 40 101 105 1 25 10211 31 16 4 1 55 103 —, uptake. Table 2 and pyruvate labeled with “C in carbon atoms 1, 2, or 3 by strains HL and W ofEhrlich asciles tumor cells Twenty-five to 40 mg of cells were incubated in 2 ml of buffer, 14 to 20 mM in lactate and pyruvate, specifically labeled; incubation period, 2 hr. Experiments with pyruvate and lactate were made with different cell preparations. or formation (jimoles/l00 mg)Isotopic, (%)LactatePyruvateNetAcetateCO,AcetateAmino specific yield acidsResidueHLPyruvateU-'4C3719368Pyruvatel-'4C+10—24148.0660.5304Pyruvate2-'4C3325347LactateU-―C4973212Lactate StrainSubstrateLabelaAnalytical,uptake 8 .62 +234 729 Lactatel-―C 2-'4C318 480.5 358 10Lactate3-―C4083715WPyruvateU-'4C4930165Pyruvatel-―C+10—605023770.5176Pyruvate2-'4C2547197LactateU-―C5728510Lactate Lactatel-―C 2-'4C—31+ 12Lactate3-―C3642616 a @,uniformly .312296 361 43 labeled. addition of an auto-oxidizable hydrogen acceptor such as PMS should stimulate the utilization of lactate but not of pyruvate. Indeed, PMS had little effect on pyruvate me tabolism in concentrations up to 50 @M,when it became inhibitory. The effect on lactate is illustrated in Table 3. In H- and HL-cells, PMS had no effect on CO2 production, 874 480 and there was a small, barely significant stimulation of ace tate production. In the W-cells, on the other hand, the oxidation of lactate was nearly doubled. It appears that only in the W-cells is the oxidation of cytoplasmic NADH rate limiting. The Activity of GPDH. According to Dionisi et al. (5), CANCER RESEARCH VOL. 34 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. Reducing E II) 0 60 HL 0 CO2 S AMINO E 8 Tumor U AMINO 6 ACETATE 40 tate but not of pyruvate. In Table 5, the effect of AOA on oCO2 ACIDS ACIDS A ACETATE UVA@ S 01 0 Transfer in Ascites mitochondria transaminates with glutamate, and the aspan tate and a-ketoglutarate pass into the cytosol where, by a 2nd transamination, oxaloacetate and glutamate are formed. The oxaloacetate is reduced to malate, and it and glutamate transferred to the mitochondria where malate is oxidized to complete the cycle. The system may serve to transfer reducing equivalents and carbon between cytosol and mitochondnia. Rognstad and Katz (1 3) introduced the transaminase inhibitor AOA to test for the operation of this type of transfer, and it has been widely used (12, 14, 21). If transamination plays a role in the oxidation of cyto plasmic NADH, AOA should inhibit the oxidation of lac 8 @ Equivalents 20 @@:—.-----@ • @—. 0 0 30 60 90 120 0 30 60 MINUTES 90 120 MINUTES Chart I. Kinetics of lactate and pyruvate utilization by HL- and W cells. Upper half, pyruvate used as substrate; lower half, lactate used as substrate. Twenty-three mg of HL- and 29 mg of W-cells (dry weight) were incubated in about 2 ml of incarbonate buffer (see text). Concentra tion of lactate and pyruvate was 16 mM; 22 and 38%, respectively, was utilized by the HL-cells, and 30 and 61%, respectively, was utilized by the W-cells. Table 3 Efftc: of PMSlactateand on 2 and acetate formation from glucose, “CConcentrationpyruvate uniformly labeled with zsi;incubation, of lactate and pyruvate, 10 mM; of PMS, I hr (same experiments as in Table 2).Pyruvate atoms)Lactate 20 (@zg carbon/l00 mg)Strain the metabolism of the acids by the HL- and W-cells is illus trated. The transaminase inhibition was manifest in the sharp drop in the ‘4Cyields in amino acids. Utilization of pyruvate was not much changed, because the increase in CO2 and acetate largely compensated for the depression in ‘4C incorporation into amino acids and residue (mainly proteins). In HL-cells in the presence of AOA, the forma tion of CO2 and acetate was not greatly altered or in creased, but with W-cells there was a significant depression in the CO2 yield and a marked depression in acetate. Re suits with H-cells resembledthosewith HL-cells. It appears that transaminase has, if any, a minor role in cytosolic NADH oxidation in H- and HL-cells, but its role in the W cells is of greaten importance. Metabolism of Glycerol and Fructose. Glycerol is metab olized at a significant rate by HL-cells, but its utilization by W-cells is one-tenth that of the HL strain (Table 6). This may reflect differences in the level of glycerol kinase or in glycerophosphate dehydrogenase. The kinase level in the W-cells was about one-half ofthat in the HL-cells (Table 5). Letnansky (10) reported that W-cells could not utilize fructose at all, and this strain appeared unique in this ne spect.We howeverfound the uptake ofglucose and fructose to be very similar. SumH PMS CO2 Acetate Sum CO2 Acetate 25 25 9 14 34 39 31 29 II 13 40+ — 26 26 6 9 32 35 33 33 7 10 73+ — 18 28 17 37 35 62 42 40 31 39 42+ — 42HL 43W Table 4 Enzyme assays on 3 strains of ascites cells For the assay from Vienna, see Ref. 9; for that from Rome, see Ref. 4. The Los Angeles data are an average of determinations of 2 batches of rats, 79 GPDH activity in H-cells was 25 times that in the HL-cells. According to Letnansky (9, 10) and Letnansky and KIc (1 1), the GPDH content of W-cells was negligible. How ever, our assay of this enzyme did not agree with these reports. As shown in Table 4, we found no great differences which by from 10 to other.@imoles/hr/mg 20% from each enzymesStrain GPDHH protein with Laboratory LDH' HK 14HI Vienna Rome Dortmund Los Angeles 250 301 160 220 12.6 5.6 6.5W Rome Dortmund Los Angeles 200 145 70 10 4.8 Vienna 410 1.4 Dortmund 137 8.3 Los Angeles 147 4.0 in the levels of GPDH in all 3 cell lines. The activity ratio LDH :GPDH in HL-cells was reported to be about 150 in Rome, but was about 10 by our assay. This ratio for the W-cells was 1600 in Vienna, as compared to about 20 in our assays. The level of the GDPH was, in our assays, of the same order as that of hexokinase. The Role of Transamination in Reducing Equivalent Transport. In the scheme of Borst (3), oxaloacetate in the differed a LDH, lactic dehydrogenase; HK, GK 2.4 hexokinase; 71 31 15.9 1.6 1.4 15 1.2 0.25 7.2 0.6 GK, 6.0 glycerol APRIL 1974 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. kinase. 875 Joseph Katz, Karl Brand, Sybil Golden, and David Rubinstein Table 5 Effect of A OA on pyruvate and lactate metabolism by HL and strains of Ehrlich ascizes tumor HL and W-cells. 46 and 55 mg (dry (dry) cells, respectively, withUptake were incubated with 2 ml buffer, 15 mr@@i in lactate or pyruvate,uniformly ‘4C, for 2 hr. Aminooxyacetate concentration, when present, 2 mM.W or formation (@tmoles/I00 mg) inhibi tion of Pyruvatea Lactate° Acetateb — + 45 43 —28 —27 +4.5 +5.0 8.0 12 28 3313 — + 55 43 +3.0 +0.8 5.5 3.5 39 5312 Pyruvate Pyruvate 1185Lactate — + 89 81 —47 —43 Lactate — + 67 40 +0.5 +0.5 AOA Pyruvate Pyruvate 688Lactate 6726W Lactate @ a By elution from columns. 1, Determined Lactate uptake —29 —23 +9.5 +7.0 24 20 —31 —18 as determined ofglycerol Table 6 by strains of Ehrlich ascites tumors Thirty to 40 mg of cells were incubated for 2 hr in 2 ml buffer with 9 to 12 msi glycerol uniformly labeled with “C. 14C incorporation mg)CO2 in (natoms carbon/l00 +TotalStrainLactatePyruvateacetateAmino acidsutilizedHL4.0.57.06.520W0.70.20.50.51.9 DISCUSSION The Levels of GPDH and the a-GPD H Cycle. Terranova et al. (17, 18) and Dionisi et al. (5) have used the H and HL strain in their studies. They suggested, from studies on oxygen uptake with or without rotenone, that the a-glyc erophosphate cycle plays a role in reducing equivalent in the H- but not the HL-cells. They correlated this with the GPDH level in 2 strains. We could not detect such a difference and find the GPDH activities to be of the same order as hexokinase. In general, the levels of mitochondrial a-glycerophos phate oxidase are less than those of the cytoplasmic de hydrogenase, and in the operation of the shuttle this oxidase is likely to be rate limiting. Dionisi et al. (5) found the level of the oxidase low and quite similar in H- and HL-cells (0.25 and 0.48 unit), compared with 3 1 and I .4 units, re spectively, for the DPNH-linked enzyme. In view of this it is difficult to see why oxidation via the glycerophosphate cycle in these 2 cell lines should have differed in their ex peniments. The reasons for the difference between the GPDH levels found in our study and those of the Rome and Vienna lab 876 53 5542 9.5 2.5 analytically CO3“C Acetate 54 4624 in close agreement 17 9.5 51 4.5 with column acids oxidationAmino 27 12 6 674 23 2.5 9.0 2.083 20 5.5 3.5 0.5 10 6.5125 9.0 2.090 5242 values; see text. analytically. Utilization transfer incorporated (jzg/atoms carbon/lOO mg) inTotal% % added ‘4C utilized Strain Substrate ResidueHL labeled oratories are puzzling. It would be of considerable interest if ascites strains with confirmed low levels of glycerophos phate dehydrogenase could be found. Reducing Equivalent Transfer. Our results indicate that the oxidation of cytosolic NADH is rate limiting in the oxi dation of lactate in the W strain, but not in 2 other strains. The inhibition by AOA suggests that a transaminase-cata lyzed pathway plays a significant role in the oxidation of cytosolic NADH in the W-cells. Aminooxyacetate in concentrations from 0.2 to 1 mM has been used as a probe for transaminase-catalyzed carbon and reducing equivalent transfer across the mitochondnial membrane in kidney (12, 13), liver (21), and heart (14). High concentrations of AOA are required completely to inhibit transamination, and the compound may not be en tirely specific and affect other sites. Great caution is needed in interpreting such results and, by themselves, they are not conclusive. However we observed no inhibition of CO2 and acetate production from pyruvate, and a significant inhibition of oxidation from lactate was observedonly with lactate in the W-cells. While transamination may play a role in the oxidation of cytosolic NADH in the W-cells, it is not likely that this is the sole pathway lent transfer for reducing equiva in this strain. In insects,the role of the a-glycerophosphat.e cyclefor the oxidation of cytosolic NADH seems established (4) but, at present, there appears to be no convincing evidence for or against the operation of this scheme in mammalian cells. Further study is required to provide firm expenimen tal support for the various schemes proposed for reducing equivalent transport. The Formation of Acetate. The accumulation of acetate is rare in mammalian cells. An interesting aspect of the metabolism of ascites cells was the high yield of acetate. This is formed to some extent from glucose, but more so from lactate and pyruvate. In the tetraploid strain CANCER RESEARCH W, ace VOL. 34 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. Reducing tate is the major product of the metabolism of the acids. The formation of acetate by tumor tissue was suggested by Elliot in 1937 (6). This received little attention until the thorough study of Hepp et a!. (7). They found low levels of acetokinase and a high level of acetyl-CoA deacylase in a numberof tumors.In normaltissues,the activityof aceto kinaseexceededthat of the hydrolase. Our results indicate considerable differences these strains as mutations 9. Letnansky, 10. of the original stock, but there is no informationto relate the metabolic 12. 13. 14. REFERENCES 15. 1. Barker, H. A. Methods Enzymol. 3: 379-381, 1962. 2. Bergmeyer, H. U. Methods of Enzymatic Analysis. New York: Aca demic Press, Inc., 1965. 3. Borst, P. Hydrogen Transport and Transport Metabolites. In: P. Karl son (ed.), Functionelle und Morphologische Organization der Zelle, pp. 137—158.Heidelberg, Germany: Springer-Verlag, Inc., 1963. 4. Bucher, T. A., and Klingenberg, M. Wegen des Wasserstoffs in der Lebenden Organization. Angew. Chem., 70: 552-570, 1958. 5. Dionisi, 0., Cittadini, G., Galeotti, T., and Terranova, T. The Role of the a-Glycerophosphate Shuttle in the Reoxidation of Cytosolic NADH in Ehrlich Ascites Tumor. Biochim. Biophys. Acta, 216: 7179, 1970. 6. Elliot, K. A. C., and Greig, M. E. Metabolism of Lactate and Pyruvic Acid in Normal and Tumor Tissue. The Formation of Succinate. Bio chem. J.,31: 1021—1032, 1937. 7. Hepp, G., Prusse, E., Weiss, H., and Wieland, 0. Essigsaure als End product des aeroben Krebsstoffwechsels. Biochem. Z., 344: 87-102, in Ascites Tumor 1966. in the met pattern to chromosomal changes. The discrepancies be tween the enzyme profiles reported by other laboratories and our findings may indicate that the “mutated― strains reverted back to the original type. Collection and preserva tion of the various strains should be of interest. Transftr 8. Katz, J., and Wals, P. A. Pentose Cycle and Reducing Equivalents in Rat Mammary-Gland Slices. Biochem. J., 128: 879-899, 1972. abolicpatternof the Ehrlichascitesstrains.Letnansky(9— 11. 11) considered Equivalents K. Unterschiede der Fermentmuster verschiedener Stämmedes Ehrlich-Ascites Tumors. Z. Krebsforsch., 70: 222-229, 1968. Letnansky, K. Strain Variations in the Utilization of Hexose by Ehrlich Ascites Tumor Cells. Biochim. Biophys. Acta, 165: 364-373, 1968. Letnansky, K., and KIc, G. M. Glycerophosphate Oxidoreductases and the Glycerophosphate Cycle in Ehrlich Ascites Tumor Cells. Arch. Biochem. Biophys., 130: 218—226,1969. Longshaw, I. D., Bowen, N. L., and Pogson, C. I. The Pathway of Gluconeogenesis in Guinea Pig Kidney. European J. Biochem., 25: 366-371,1972. Rognstad, R., and Katz, J. Gluconeogenesis in the Kidney Cortex. Biochem. J., 116: 483-492, 1970. Safer, B., Smith, C. M., and Williamson, J. R. Control of the Trans port of Reducing Equivalents across the Mitochondrial Membrane in Perfused Rat Heart. J. Mol. Cellular Cardiol., 2: I I I - I 24, 197I. Shonk, G. E., and Boxer, G. E. Enzyme Patterns in Human Tissues. Methods for Determination of Glycolytic Enzymes. Cancer Res., 24: 709-721, 1964. 16. Shulman, M., and Wood, H. G. Determination and Degradation of Microquantities of Acetate. Anal. Biochem., 39: 505-520, 1971. 17. Terranova, T., Baldi, S., and Dionisi, 0. Further Observations on the Glucose-induced Respiration in Ehrlich Ascites Cells. Arch. Biochem. Biophys., 130: 594-603, 1969. 18. Terranova, T., Galeotti, T., Baldi, S., and Neri, G. Kinetics of Oxygen Uptake in Ehrlich Ascites Tumor Cells Treated with Rotenone plus Glucose. Biochem. Z., 346: 439-445, 1967. 19. Umbreit, W. W., Burns, R. H. and Stauffer, J. F. Manometric Tech niques, Ed. 4. Minneapolis, Minn.: Burgess Publishing Co., 1964. 20. Weinhouse, S. Oxidative Metabolism of Neoplastic Tissues. Advan. Cancer Res., 3: 1958. 21. Williamson, J. R., Jacob, A., and Refino, C. Control of the Removal of Reducing Equivalents from the Cytosol in Perfused Rat Liver. J. Biol. Chem., 246: 7632-7641, 1971. APRIL 1974 Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research. 877 Lactate and Pyruvate Metabolism and Reducing Equivalent Transfer in Ehrlich Ascites Tumor Joseph Katz, Karl Brand, Sybil Golden, et al. Cancer Res 1974;34:872-877. Updated version E-mail alerts Reprints and Subscriptions Permissions Access the most recent version of this article at: http://cancerres.aacrjournals.org/content/34/4/872 Sign up to receive free email-alerts related to this article or journal. To order reprints of this article or to subscribe to the journal, contact the AACR Publications Department at [email protected]. To request permission to re-use all or part of this article, contact the AACR Publications Department at [email protected]. Downloaded from cancerres.aacrjournals.org on April 30, 2017. © 1974 American Association for Cancer Research.