Summary
It has been demonstrated in several diving vertebrates that succinate, a component of the Krebs cycle, accumulates in blood during breath-hold dives. The production of succinate is thought to result from amino acid catabolism. Our purpose was to determine whether succinate accumulation occurs in man during muscular activity requiring anaerobic energy contribution. Experiments using an endurance athlete included apneic work on an underwater ergometer and treadmill running to exhaustion. During 1 min breath-hold “dives” in cold water while exercising at a work rate equivalent to 62% of \(\dot V\)O2max, venous succinate increased from 42 Μmoles/l (M×10−6) at rest to 125 M×10−6. The treadmill run elicited \(\dot V\)O2max and increased succinate from a similar resting value to 93 M×10−6. Increases in alanine, lactate, and pyruvate were observed for both types of exercise. The findings confirm that succinate accumulation also occurs in man. It was suggested that amino acid catabolism may provide a source of anaerobic energy production in addition to glycolysis. However, the importance of the proposed energy pathway remains to be quantified.
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References
Aoki, T. T., Brennan, M. F., Muller, W. A., Moore, F. D., Cahill, G. F., Jr.: Effect of insulin on muscle glutamate uptake. J. clin. Invest. 51, 2889–2899 (1972)
De Zoeten, L. W., Tipker, J.: Intermediary metabolism of the liver fluke, Fasciola hepatica. II. Hydrogen transport and phosphorylation. Hoppe-Seylers physiol. Chem. 350, 691–695 (1969)
Hoberman, H. D., Prosky, L.: Evidence of reduction of fumarate to succinate in perfused rat liver under conditions of reduced O2 tension. Biochim. biophys. Acta (Amst.) 148, 392 (1967)
Hochachka, P. W., Fields, J., Mustafa, T.: Animal life without oxygen: basic biochemical mechanisms. Amer. Zoologist 13, 543–555 (1973)
Hochachka, P. W., Owen, T. G., Allen, J. F., Wittow, G. C.: Multiple end-products of anaerobiosis in diving vertebrates. Comp. Biochem. Physiol. 50, 17–22 (1975)
Hochachka, P. W., Somero, G. N.: Strategies of biochemical adaptation, pp. 1–350. Philadelphia: Saunders 1973
Hochachka, P. W., Mustafa, T.: Invertebrate facultative anaerobiosis. Science 178, 1056–1060 (1972)
Moffet, F. J., Wang, T. T., Bridger, W. A.: Succinyl coenzyme. A synthetase of E. coli: effects of phosphoenzyme formation and of substrate binding on the reactivity and stability of the enzyme. J. biol. Chem. 247, 8139–8144 (1972)
Morlock, J. F., Dressendorfer, R. H.: Modification of a standard bicycle ergometer for underwater use. Undersea Biomed. Res. 1, 335–342 (1974)
Olsen, C. R., Fanestil, D. D., Scholander, P. F.: Some effects of apneic underwater diving on blood gases, lactate, and pressure in man. J. appl. Physiol. 17, 938–942 (1962)
Penney, D. G., Cascarano, J.: Anaerobic rat heart: effects of glucose and tricarboxylic acid cycle metabolites on metabolism and physiological performance. Biochem. J. 118, 221–227 (1970)
Sanadi, D. R., Fluharty, A. L.: On the mechanism of oxidative phosphorylation. VII. The energy-requiring reduction of NAD by succinate and the energy-yielding oxidation of NADH by fumarate. Biochemistry 2, 523–528 (1963)
Scholander, P. F.: Experimental investigations on the respiratory function in diving mammals and birds. Hvalradets Skrifter Norske Videnskaps-Adad Oslo 22, 1–131 (1940)
Scholander, P. F., Hammel, H. T., LeMessurier, H., Hemmingsen, E., Garey, W.: Circulatory adjustments in pearl divers. J. appl. Physiol. 17, 184–190 (1962)
Williamson, J. R., Corkey, B. E.: Assays of intermediates of the citric acid cycle by flurometric enzyme methods. In: Methods in enzymology, Vol. 13 (J. M. Lowenstein, ed.), pp. 434–515. New York: Academic Press 1969
Wilson, M. A., Cascarano, J.: The energy-yielding oxidation of NADH by fumarate in submitochondrial particles of rat tissues. Biochim. biophys. Acta (Amst.) 216, 54–62 (1970)