Abstract
Activity of the pentose-phosphate pathway in several rat tissues was investigated, developing a new method that gives the activity of each phase (oxidative and non-oxidative) as well as the whole pathway separately. Our results demonstrate that this method is easy to carry out and that it has not the problems of indirect determinations of the previous ones. The activities of the oxidative and non-oxidative phases assayed separately gives us new information on the design of the pathway in the different tissues, from which several conclusions about the physiological role of this pathway can be derived. In all cases the activity of the oxidative phase was much higher than the non-oxidative one, and the global activity of the whole pathway was the same as the activity of the non-oxidative phase. The highest activity was found in lactating mammary gland and adipose tissue. Lung and liver showed to have a moderately high activity. Brain, kidney, skeletal muscle, and intestinal mucosa showed to have also a significant activity although less than other tissues. The switch in the mammary gland from the non-lactating state to the lactating one causes a very high increase of activity of 22 times, remaining the same ratio between the activity of the two phases.
Similar content being viewed by others
References
Katz J, Rognstad R: The metabolism of tritiated glucose by rat adipose tissue. J Biol Chem 241: 3600–3610, 1966
Winberry L, Holton D: Rat liver glucose 6-P dehydrogenase. Dietary regulation of the rate of synthesis. J Biol Chem 252: 7796–7801, 1977
Ros M, Cubero A, Lobato M F, García-Ruiz JP, Moreno FJ: Fatty acyl-CoA as a feedback regulators of hexose monophosphate shunt in rat adipocytes. Mol Cell Biochem 63: 119–123, 1984
Wood T: The pentose phosphate pathway. Academic Press, Orlando, 1985
Baquer NZ, Hothershall JS, McLean P: Function and regulation of the pentose phosphate pathway in brain. Curr Top Cell Reg 29: 265–289, 1988
Meléndez-Hevia E: La vía de las pentosas-fosfato. In: E. Herrera (ed). Bioquímica. Interamericana/Mc-Graw-Hill, Madrid., 1991, pp 501–528
Haut M J, London J W, Garfinkel D: Simulation of the pentose cycle in lactating rat mammary gland. Biochem J 138: 511–524, 1974
Crawford JM, Blum JJ: Quantitative analysis of flux along the gluconeogenic, glycolytic and pentose phosphate pathways under reducing conditions in hepatocytes isolated from fed rats. Biochem J 212: 595–598, 1983
Fell DA, Small R: Fat synthesis in adipose tissue. An examination of stoichiometric constraints. Biochem J 238: 781–786, 1986
McIntyre LM, Thorburn DR, Bubb WA, Kuchel PW: Comparison of computer simulations of the F-type and L-type non-oxidative hexose monophosphate shunts with 31P-NMR experimental data from human erythrocytes. Eur J Biochem 180: 399–420, 1989
Kuchel PW, Berthon HA, Bubb WA, Bulliman BT, Collins JG: Computer simulation of the pentose-phosphate pathway and associated metabolism used in conjunction with NMR experimental data from human erythrocytes. Biomed Biochim Acta 49: 757–770, 1990
Nuño JC, Sánchez-Valdenebro I, Pérez-Iratxeta C, Meléndez-Hevia E, Montero F: Network organization of cell metabolism: Monosaccharide interconversion. Biochem J 324: 103–111, 1997
Meléndez-Hevia E, Isidoro A: The game of the pentose phosphate cycle. J Theor Biol 117: 251–263, 1985
Meléndez-Hevia E, Torres NV: Economy of design in metabolic pathways: Further remarks on the game of the pentose phosphate cycle. J Theor Biol 132: 97–111, 1988
Meléndez-Hevia E: The game of the pentose phosphate cycle: A mathematical approach to study the optimization in design of metabolic pathways during evolution. Biomed Biochim Acta 49: 903–916, 1990
Meléndez-Hevia E, Waddell TG, Montero F: Optimization of metabolism: the evolution of metabolic pathways toward simplicity through the game of the pentose phosphate cycle. J Theor Biol 166: 201–220, 1994
Landau BR: Use of radioisotopes in elucidating the nature of and quantitating the pentose pathway. In: T. Wood (ed). The pentose phosphate pathway. Academic Press, Orlando, 1985, pp 153–178
Katz J, Wood HG: The use of 14CO2 yields from glucose-1-and-6-14C for the evaluation of the pathways of glucose metabolism. J Biol Chem 238: 517–523, 1963
Wood T: Ref. 4, pp 3–16
Williams JF, Arora KK, Longenecker JP: The pentose pathway: A random harvest. Int J Biochem 19: 749–817, 1987
Kacser H, Porteous JW: Control of metabolism: What do we have to measure? Trends Biochem Sci 12: 5–15, 1987
Schuster S, Heinrich R: The definitions of metabolic control analysis revisited. BioSystems 27: 1–15, 1992
Fell DA: Metabolic control analysis: A survey of its theoretical and experimental development. Biochem J 286: 313–330, 1992
Salter M, Knowles R, Pogson CI: Metabolic control. Essais Biochem 28: 1–12, 1994
Novello F, McLean P: The pentose phosphate pathway of glucose metabolism. Measurement of the non-oxidative reactions of the cycle. Biochem J 107: 775–791, 1968
Bradford MM: A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72: 248–254, 1976
McCormick K, Mick GJ: Kinetic superiority of intra vs. extracellular pentose pathway flux: Studies in porous adipocytes. Am J Physiol 261: C476–C481, 1991
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Cabezas, H., Raposo, R.R. & Meléndez-Hevia, E. Activity and metabolic roles of the pentose phosphate cycle in several rat tissues. Mol Cell Biochem 201, 57–63 (1999). https://doi.org/10.1023/A:1007042531454
Issue Date:
DOI: https://doi.org/10.1023/A:1007042531454